nohup is necessary in Bash?

Check your configuration as follows:

$ shopt
...
huponexit       off
...
$

As you can see, `huponexit` is `off`. So you don't have to use `nohup` in this case.

AdSense is not showing up on Blogspot

If you set up AdSense on Blogspot but ADs are not showing up,

wait a few minutes.

For me, it was blanks but after a few minutes ADs shows up.

Deploy a jar file to Maven repository in Gradle

To deploy a jar file to Maven repository in Gradle,

add the following configuration to `build.gradle`:

apply plugin: 'maven'

repositories {
    mavenLocal()
    jcenter()
    maven { url "http://repo.izeye.com:8080/repository/internal" }
}

uploadArchives {
    repositories {
        mavenDeployer {
            repository(url: "http://repo.izeye.com:8080/repository/internal") {
                authentication(userName: "admin", password: "1234")
            }
        }
    }
}

If you encounter the following error:

Could not find metadata :test/maven-metadata.xml in remote (http://repo.izeye.com:8080/repository/internal)

make sure you added it to `repositories`.

Reference:
https://docs.gradle.org/current/userguide/maven_plugin.html

rsync: failed to connect to 1.2.3.4: Connection refused (111)

If you encounter the following error:

$ rsync -avr 1.2.3.4::I/home/izeye/test/ .
rsync: failed to connect to 1.2.3.4: Connection refused (111)
rsync error: error in socket IO (code 10) at clientserver.c(124) [receiver=3.0.6]
$

checkout your rsync configuration as follows:

$ sudo vi /etc/xinetd.d/rsync

service rsync
{
        disable = yes
        flags           = IPv6
        socket_type     = stream
        wait            = no
        user            = root
        server          = /usr/bin/rsync
        server_args     = --daemon
        log_on_failure  += USERID
}

and change `disable` from `yes` to `no`.

Restart the xinetd as follows:

$ sudo /etc/init.d/xinetd restart

As a side note, if you encounter the following error:

$ rsync -avr 1.2.3.4::I/home/izeye/test/ .
@ERROR: access denied to I from unknown (5.6.7.8)
rsync error: error starting client-server protocol (code 5) at main.c(1503) [receiver=3.0.6]
$

checkout your `/etc/rsyncd.conf`, especially `hosts allow` and `hosts deny` values.

rm: cannot unlink `/c/Users/izeye/IdeaProjects/impression-neo/.git/rebase-merge/.git-rebase-todo.swp': Permission denied

If you encounter the following error during aborting rebase:

C:\Users\izeye\IdeaProjects\impression-neo>git rebase --abort
rm: cannot unlink `/c/Users/izeye/IdeaProjects/impression-neo/.git/rebase-merge/.git-rebase-todo.swp': Permission denied
rm: cannot remove directory `/c/Users/izeye/IdeaProjects/impression-neo/.git/rebase-merge': Directory not empty

C:\Users\izeye\IdeaProjects\impression-neo>

Kill `vim.exe`.

Force to push a specifc branch to origin in Git

To force to push a specifc branch to origin in Git,

do as follows:

git push -f origin gh-1004

Reference:
http://stackoverflow.com/questions/11453807/force-push-current-branch

File exists. error: failed to run pack-refs

If you encounter the following error:

Error pulling origin
fatal: Unable to create 'C:/Users/nbp/IdeaProjects/xxx/.git/packed-refs.lock': File exists. error: failed to run pack-refs

do as follows:

del .git/packed-refs.lock

although I don't know why this happened.

How to exclude `src/main/resources` from a jar file in Gradle

To exclude `src/main/resources` from a jar file in Gradle, add the following to `build.gradle`:

processResources {
    exclude '**'
}

How to refresh a snapshot dependency in Gradle

To refresh a snapshot dependency in Gradle, add the following to `build.gradle`:

configurations.all {
    resolutionStrategy.cacheChangingModulesFor 0, 'seconds'
}

Reference:
https://discuss.gradle.org/t/how-to-get-gradle-to-download-newer-snapshots-to-gradle-cache-when-using-an-ivy-repository/7344

ElasticsearchIllegalArgumentException[failed to execute script]; nested: ScriptException[scripts of type [inline], operation [update] and lang [groovy] are disabled];

When you use inline scripting as follows:

$ curl -XPOST 'localhost:9200/customer/external/1/_update?pretty' -d '
{
  "script" : "ctx._source.age += 5"
}'

you might get the following error:

{
  "error" : "ElasticsearchIllegalArgumentException[failed to execute script]; nested: ScriptException[scripts of type [inline], operation [update] and lang [groovy] are disabled]; ",
  "status" : 400
}

Because inlining scripting is disabled since 1.4.3, you should enable inline scripting explicitly as follows:

config/elasticsearch.yml

script.inline: on

You can check the result as follows:

$ curl 'localhost:9200/customer/external/1?pretty'

References:
https://www.elastic.co/guide/en/elasticsearch/reference/1.7/_updating_documents.html
https://www.elastic.co/guide/en/elasticsearch/reference/1.7/modules-scripting.html

How to use a constructor when deserializing in Jackson

To use a constructor when deserializing in Jackson,

do as follows:

@Data
public class ClickUrl {

  private final String url;
  private String finalUrl;

  @JsonCreator
  public AdcrClickUrl(@JsonProperty("url") String url) {
    this.url = url;
  }

}

Reference:
http://www.cowtowncoder.com/blog/archives/2011/07/entry_457.html

How to add images to output with AsciiDoctor Gradle plugin

To add images to output with AsciiDoctor Gradle plugin

add the following configuration to your `build.gradle` file:

asciidoctor {
    resources {
        from (sourceDir) {
            include "**/*.png"
        }
    }
}

Reference:
https://github.com/asciidoctor/asciidoctor-gradle-plugin

ERR_CONNECTION_ABORTED in Chrome when you deploy a WAR file to Tomcat via Manager App

You might get ERR_CONNECTION_ABORTED in Chrome when you deploy a WAR file to Tomcat via a Manager App.

If so, check your log file for the Manager App, `logs/manager.2015-10-30.log`.

It might look like this:

30-Oct-2015 15:49:08.586 SEVERE [http-nio-8080-exec-8] org.apache.catalina.core.ApplicationContext.log HTMLManager: FAIL - Deploy Upload Failed, Exception: org.apache.tomcat.util.http.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (59114627) exceeds the configured maximum (52428800)
 java.lang.IllegalStateException: org.apache.tomcat.util.http.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (59114627) exceeds the configured maximum (52428800)
        at org.apache.catalina.connector.Request.parseParts(Request.java:2804)
        at org.apache.catalina.connector.Request.parseParameters(Request.java:3073)
        at org.apache.catalina.connector.Request.getParameter(Request.java:1095)
        at org.apache.catalina.connector.RequestFacade.getParameter(RequestFacade.java:380)
        at org.apache.catalina.filters.CsrfPreventionFilter.doFilter(CsrfPreventionFilter.java:185)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.apache.catalina.filters.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:108)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:217)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:614)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
        at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
        at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
        at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673)
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.lang.Thread.run(Thread.java:745)
Caused by: org.apache.tomcat.util.http.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (59114627) exceeds the configured maximum (52428800)
        at org.apache.tomcat.util.http.fileupload.FileUploadBase$FileItemIteratorImpl.<init>(FileUploadBase.java:811)
        at org.apache.tomcat.util.http.fileupload.FileUploadBase.getItemIterator(FileUploadBase.java:256)
        at org.apache.tomcat.util.http.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:280)
        at org.apache.catalina.connector.Request.parseParts(Request.java:2734)
        ... 28 more

If you encounter the above error, you should change file size in `webapps/manager/WEB-INF/web.xml` appropriately:

    <multipart-config>
      <!-- 50MB max -->
      <max-file-size>52428800</max-file-size>
      <max-request-size>52428800</max-request-size>
      <file-size-threshold>0</file-size-threshold>
    </multipart-config>

How to dump a text file to byte values in hex

To dump a text file to byte values in hex,

use the following command:

xxd test.txt

How to list all exported system environment variables in Linux

To list all exported system environment variables in Linux,

use `printenv` or `export -p`.

Make sure a corresponding org.thymeleaf.doctype.resolution.IDocTypeResolutionEntry implementation is provided by you dialect

When you use Thymeleaf with Spring Boot and use the following DOCTYPE:

<!DOCTYPE html SYSTEM "http://www.thymeleaf.org/dtd/xhtml1-strict-thymeleaf-4.dtd">

you will get the following errors:

2015-10-07 10:19:45.957 ERROR 3301 --- [io-18080-exec-1] org.thymeleaf.TemplateEngine             : [THYMELEAF][http-nio-18080-exec-1] Exception processing template "restaurants/add": Unsupported entity requested with PUBLICID "null" and SYSTEMID "http://www.thymeleaf.org/dtd/xhtml1-strict-thymeleaf-4.dtd". Make sure a corresponding org.thymeleaf.doctype.resolution.IDocTypeResolutionEntry implementation is provided by you dialect
2015-10-07 10:19:45.964 ERROR 3301 --- [io-18080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.thymeleaf.exceptions.TemplateProcessingException: Unsupported entity requested with PUBLICID "null" and SYSTEMID "http://www.thymeleaf.org/dtd/xhtml1-strict-thymeleaf-4.dtd". Make sure a corresponding org.thymeleaf.doctype.resolution.IDocTypeResolutionEntry implementation is provided by you dialect] with root cause
org.thymeleaf.exceptions.TemplateProcessingException: Unsupported entity requested with PUBLICID "null" and SYSTEMID "http://www.thymeleaf.org/dtd/xhtml1-strict-thymeleaf-4.dtd". Make sure a corresponding org.thymeleaf.doctype.resolution.IDocTypeResolutionEntry implementation is provided by you dialect
at org.thymeleaf.templateparser.EntityResolver.resolveEntity(EntityResolver.java:75) ~[thymeleaf-2.1.4.RELEASE.jar:2.1.4.RELEASE]
...

You should use the following DOCTYPE:

<!DOCTYPE html SYSTEM "http://www.thymeleaf.org/dtd/xhtml1-strict-thymeleaf-spring4-4.dtd">

Reference:
http://stackoverflow.com/questions/25132189/thymleaf-unsupported-entity-requested-with-publicid-null

Kibana doesn't recognize changed `not_analyzed`

When you change index type to `not_analyzed`

and Kibana doesn't recognize `not_analyzed`,

do as follows:

Settings -> Reload field list

and try again.

Make a field as `not_analyzed` index in Elasticsearch

To make a field as `not_analyzed` index in Elasticsearch,

use `@Field` as follows:

  @Field(type = FieldType.String, index = FieldIndex.not_analyzed)
  private String name;

and check as follows:

curl -XGET 'http://localhost:9200/event/_mapping?pretty'

and then you will see as follows:

          "name" : {
            "type" : "string",
            "index" : "not_analyzed"
          },

Note that the following annotation doesn't work:

  @Field(index = FieldIndex.not_analyzed)

I'm not sure why type inference doesn't work.

Set a `java.util.Date` typed field as `date` type in Elasticsearch

To set a `java.util.Date` typed field as `date` type in Elasticsearch,

use `@Field` as follows:

  @Field(type = FieldType.Date)
  private Date timestamp;

and check as follows:

curl -XGET 'http://localhost:9200/event/_mapping?pretty'

and then you will see as follows:

          "timestamp" : {
            "type" : "date",
            "format" : "dateOptionalTime"
          }

Change encoding for main and test sources in Gradle

compileJava.options.encoding = 'UTF-8'
compileTestJava.options.encoding = 'UTF-8'

Reference:
https://github.com/huxi/sulky/blob/master/build.gradle

QueryDSL + JPA + Gradle in IntelliJ

`build.gradle`:

apply plugin: 'idea'

idea {
    module {
        sourceDirs += file('generated/')
    }
}

dependencies {
    ...
    compile("com.mysema.querydsl:querydsl-jpa:$querydslVersion")
    compile("com.mysema.querydsl:querydsl-apt:$querydslVersion:jpa")
    ...
}

Setup IntelliJ:

File -> Settings...

Compiler -> Annotation Processors

`Enable annotation processing`

Store generated sources relative to: `Module content root`

Reference:
http://bsideup.blogspot.kr/2015/04/querydsl-with-gradle-and-idea.html

Print errors in Flask

Use debug flag as follows:

app.run(debug=True)

Reference:
http://blog.luisrei.com/articles/flaskrest.html

Create an object in Python

You can create an object as follows:

class DiskSpace(object):
  def __init__(self, total, free):
    self.total = total
    self.free = free

  def __str__(self):
    return "total: %d, free: %d" % (self.total, self.free)

diskSpace = DiskSpace(100, 50)
print diskSpace

References:
http://stackoverflow.com/questions/15081542/python-creating-objects
http://stackoverflow.com/questions/727761/python-str-and-lists
http://www.pythonforbeginners.com/concatenation/string-concatenation-and-formatting-in-python

`Hello, world!` by Flask in Linux

Install pip if not installed:

sudo yum install python-pip

Install Flask if not installed:

sudo pip install Flask

Don't make your sample filename as `flask.py`.

If you do so, you will get the following error:

Traceback (most recent call last):
  File "flask.py", line 1, in <module>
    from flask import Flask
  File "/home/izeye/workspaces/izeye/python/flask.py", line 1, in <module>
    from flask import Flask
ImportError: cannot import name Flask

In `test_flask.py`:

from flask import Flask

app = Flask(__name__)

@app.route("/")
def hello():
  return "Hello, world!"

if __name__ == "__main__":
  app.run()

You can run it as follows:

python test_flask.py

References:
http://flask.pocoo.org/
http://stackoverflow.com/questions/14792605/python-flask-import-error

How to get disk usage by Python in Linux

To get disk usage,

you can use the following code:

import os

statvfs = os.statvfs('/')

total_disk_space = statvfs.f_frsize * statvfs.f_blocks
free_disk_space = statvfs.f_frsize * statvfs.f_bfree
disk_usage = (total_disk_space - free_disk_space) * 100.0 / total_disk_space

print total_disk_space
print free_disk_space
print disk_usage

Reference:
http://stackoverflow.com/questions/4260116/find-size-and-free-space-of-the-filesystem-containing-a-given-file

How to download JDK with `wget`

To download JDK with `wget`,

use the following commnad:

wget --no-check-certificate --header="Cookie: oraclelicense=accept-securebackup-cookie" "http://download.oracle.com/otn-pub/java/jdk/8u60-b27/jdk-8u60-linux-x64.tar.gz"

Reference:
https://gist.github.com/hgomez/4697585

How to get 2 days ago in Linux

To get 2 days ago in Linux,

you can do as follows:

date --date="-2day" "+%Y.%m.%d"

Reference:
http://www.cyberciti.biz/tips/linux-unix-get-yesterdays-tomorrows-date.html

Delete documents in Elasticsearch

If you want to delete documents of a specific type,

you can delete the documents as follows:

$ curl -XDELETE http://localhost:9200/logstash-2015.09.05/logs                          
{"acknowledged":true}
$

If you want to delete documents of all types under a specific index,

you can delete the documents as follows:

$ curl -XDELETE http://localhost:9200/logstash-2015.09.05                                
{"acknowledged":true}
$

References:
http://stackoverflow.com/questions/23917327/delete-all-documents-from-index-type-without-deleting-type
https://www.elastic.co/blog/what-is-an-elasticsearch-index

How to get the number of documents and the total size in an index in Elasticsearch

To get the number of documents and the total size in an index,

use the following command:

curl -XGET 'http://localhost:9200/logstash-2015.09.05/_stats?pretty'

`logstash-2015.09.05` will be your index.

Reference:
https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-stats.html

How to get all indices in Elasticsearch

To get all indices in Elasticsearch,

use the following command:

curl -XGET 'http://localhost:9200/*?pretty'

Reference:
https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-get-index.html

How to handle nested backticks (`) in Bash

If you use nested backticks (`),

you will get the following errors:

$ echo `printf '%02d' $((10#`date +%M` / 30 * 30))`
-bash: command substitution: line 1: unexpected EOF while looking for matching `)'
-bash: command substitution: line 2: syntax error: unexpected end of file
-bash: command substitution: line 1: syntax error near unexpected token `)'
-bash: command substitution: line 1: ` / 30 * 30))'
date +%M
$

Use $() instead as follows:

$ echo `printf '%02d' $((10#$(date +%M) / 30 * 30))`
00
$

Reference:
http://stackoverflow.com/questions/2657012/how-to-properly-nest-bash-backticks

How to add a leading zero in Bash

If you want to add a leading zero to a number,

you can do as follows:

$ echo `printf '%02d' 8`
08
$

Reference:
http://stackoverflow.com/questions/55754/bash-script-to-pad-file-names

How to handle a leading zero in Bash

If you have a leading zero in a number,

the number is handled as octal number as follows:

$ echo $((08 + 1))
-bash: 08: value too great for base (error token is "08")
$

To handle it as decimal number you have to do as follows:

$ echo $((10#08 + 1))
9
$

Reference:
http://blog.famzah.net/2010/08/07/beware-of-leading-zeros-in-bash-numeric-variables/

How to get total size of specific files in Linux

To get total size of specific files in Linux,

you can do as follows:

du -ch debug.log.*

Reference:
http://unix.stackexchange.com/questions/72661/show-sum-of-file-sizes-in-directory-listing

How to import a Gradle project from a Git repository in STS (or Eclipse)

1. Clone the Git repository:

Window -> Show View -> Other...

Git -> Git Repositories

Clone a Git repository -> Clone URI

2. Install Gradle plugin:

Help -> Eclipse Marketplace... -> Gradle Integration for Eclipse 3.7.0.RELEASE

3. Import the project:

Import -> Gradle -> Gradle Project

How to override Spring Boot application.properties in tests

To override Spring Boot application.properties in tests,

use the following annotations:

@TestPropertySource(properties = {"spring.cache.type=simple"})
@DirtiesContext

References:
http://stackoverflow.com/questions/29669393/override-default-spring-boot-application-properties-settings-in-junit-test
https://github.com/spring-projects/spring-boot/issues/2198

org.springframework.mail.MailAuthenticationException: Authentication failed; nested exception is javax.mail.AuthenticationFailedException

When you try to send an email with Gmail SMTP,

you might get the following exception:

org.springframework.mail.MailAuthenticationException: Authentication failed; nested exception is javax.mail.AuthenticationFailedException: 534-5.7.14 <https://accounts.google.com/ContinueSignIn?sarp=1&scc=1&plt=AKgnsbuBm
534-5.7.14 7mH3ysGBLpLeQAGDrZrkNi3uUJsTPF6P8pszrRFOKqdKWGKsDpWBkcrvwJC02xOAQsW7b-
...
534-5.7.14 zFvhhWx1SQ-yRuGO0fa8JMMszw3E> Please log in via your web browser and
534-5.7.14 then try again.
534-5.7.14  Learn more at
534 5.7.14  https://support.google.com/mail/answer/78754 z16sm15149096pbt.3 - gsmtp

at org.springframework.mail.javamail.JavaMailSenderImpl.doSend(JavaMailSenderImpl.java:424)
at org.springframework.mail.javamail.JavaMailSenderImpl.send(JavaMailSenderImpl.java:307)
at org.springframework.mail.javamail.JavaMailSenderImpl.send(JavaMailSenderImpl.java:296)

Go to the following URL:

https://www.google.com/settings/security/lesssecureapps

Set `Access for less secure apps` to `Turn on`.

Reference:
http://stackoverflow.com/questions/20337040/gmail-smtp-debug-error-please-log-in-via-your-web-browser

java.lang.IllegalArgumentException: Unknown ordinal value [100] for enum class [com.izeye.test.event.domain.EventSource]

If you try to fetch an undefined enum ordinal value in JPA backed by Hibernate,

you will get the following exception:

java.lang.IllegalArgumentException: Unknown ordinal value [100] for enum class [com.izeye.test.event.domain.EventSource]
    at org.hibernate.type.EnumType$OrdinalEnumValueMapper.fromOrdinal(EnumType.java:391)
    at org.hibernate.type.EnumType$OrdinalEnumValueMapper.getValue(EnumType.java:381)
    at org.hibernate.type.EnumType.nullSafeGet(EnumType.java:107)
    at org.hibernate.type.CustomType.nullSafeGet(CustomType.java:127)
    at org.hibernate.type.AbstractType.hydrate(AbstractType.java:106)
    at org.hibernate.persister.entity.AbstractEntityPersister.hydrate(AbstractEntityPersister.java:2969)
    at org.hibernate.loader.Loader.loadFromResultSet(Loader.java:1696)

If you want to avoid the above exception and just get `null` instead,

add the following code:

@Converter(autoApply = true)
public class EventSourceConverter implements AttributeConverter<EventSource, Integer> {

  @Override
  public Integer convertToDatabaseColumn(EventSource eventSource) {
    return eventSource.ordinal();
  }

  @Override
  public EventSource convertToEntityAttribute(Integer ordinal) {
    EventSource[] values = EventSource.values();
    if (ordinal >= values.length) {
      return null;
    }
    return values[ordinal];
  }

}

Reference:
http://www.javacodegeeks.com/2014/05/jpa-2-1-type-converter-the-better-way-to-persist-enums.html

org.hibernate.AssertionFailure: possible non-threadsafe access to session

When you are using a sequence for an entity

and persist it, detach it, and merge it in a transaction,

you will get the following error:

ERROR: HHH000099: an assertion failure occured (this may indicate a bug in Hibernate, but is more likely due to unsafe use of the session): org.hibernate.AssertionFailure: possible non-threadsafe access to session

You should flush it before merging it.

Unfortunately I didn't understand the reason.

I'm not sure it's a bug or wrong usage.

It was just a test code and I'm not sure it could be a real scenario or not.

This inspection controls whether the Persistence QL Queries are error-checked

If you get the following error in IntelliJ:

Can't resolve symbol 'Person' less... (⌘F1)
This inspection controls whether the Persistence QL Queries are error-checked

do the following:

Inspection 'Query language checks' options -> Disable inspection

Reference:
http://devday.tistory.com/entry/Cant-resolve-symbol-Note

ERROR: Sequence "HIBERNATE_SEQUENCE" not found

If you have the following with H2:

@Id
@GeneratedValue
private Long id;

you might get the following error:

Hibernate:
    call next value for hibernate_sequence
8월 15, 2015 2:49:23 오후 org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions
WARN: SQL Error: 90036, SQLState: 90036
8월 15, 2015 2:49:23 오후 org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions
ERROR: Sequence "HIBERNATE_SEQUENCE" not found; SQL statement:
call next value for hibernate_sequence [90036-187]
ex: javax.persistence.PersistenceException: org.hibernate.exception.GenericJDBCException: could not prepare statement

I guess `GenerationType.AUTO` uses `GenerationType.SEQUENCE`

and H2 doesn't support it.

I tried with `GenerationType.IDENTITY` as follows:

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;

and it works.

UPDATED:

Actually H2 DOES support `GenerationType.SEQUENCE`

and you should do as follows:

@Entity
@SequenceGenerator(
name = "USER_SEQ_GENERATOR",
sequenceName = "USER_SEQ",
initialValue = 1, allocationSize = 1)
public class User {

@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "USER_SEQ_GENERATOR")
private Long id;

...
}

How to change a version of dependency managed by Spring Boot in Gradle

To change the following in `spring-boot-dependencies`:

<spring-data-releasetrain.version>Gosling-RC1</spring-data-releasetrain.version>

add the following in `build.gradle`:

ext['spring-data-releasetrain.version'] = 'Gosling-M1'

Reference:
http://docs.spring.io/spring-boot/docs/current-SNAPSHOT/reference/htmlsingle/#howto-customize-dependency-versions

Exclude specific tasks of a sub-project in Gradle

To exclude specific tasks of a sub-project in Gradle,

do as follows:

gradle build -x :test-common:startScripts -x :test-common:bootRepackage

Run a specific task of a sub-project in Gradle

To run a specific task of a sub-project in Gradle,

do as follows:

gradle :test-common:startScripts

No signature of method: build_59tj2ra5d1mn9tk0vrfinvo79c$_run_closure2.id() is applicable for argument types: (java.lang.String) values: [org.asciidoctor.convert]

You might encounter the following exception:

FAILURE: Build failed with an exception.

* Where:
Build file '/home/izeye/applications/test/build.gradle' line: 9

* What went wrong:
A problem occurred evaluating root project 'test'.
> No signature of method: build_59tj2ra5d1mn9tk0vrfinvo79c$_run_closure2.id() is applicable for argument types: (java.lang.String) values: [org.asciidoctor.convert]
  Possible solutions: is(java.lang.Object), is(java.lang.Object), find(), find(), find(groovy.lang.Closure), find(groovy.lang.Closure)

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

BUILD FAILED

Gradle version was 1.12.

Just upgrading to 2.5 fixed the problem.

Error: Invalid value for attribute d="MNaN,82.5LNaN,41.25LNaN,0LNaN,123.75LNaN,330"

You might encounter the following error in D3.js:

Error: Invalid value for <path> attribute d="MNaN,82.5LNaN,41.25LNaN,0LNaN,123.75LNaN,330"

If you get the following date and time format:

"collectedTime" : "2015-05-19 14:48:40",

you need to parse it as follows:

        svg.x.domain(d3.extent(data, function (d) {
//            return d.collectedTime;
            var parsedTime = d3.time.format("%Y-%m-%d %H:%M:%S").parse(d.collectedTime);
            return parsedTime;
        }));

        svg.line = d3.svg.line()
                .x(function (d) {
                    //return svg.x(d.timestamp);
                    //return svg.x(d.collectedTime);
                    var parsedTime = d3.time.format("%Y-%m-%d %H:%M:%S").parse(d.collectedTime);
                    return svg.x(parsedTime);
                })
                .y(function (d) {
                    return svg.y(valueFunction(d));
                });

References:
http://stackoverflow.com/questions/26070783/invalid-value-for-path-attribute
https://github.com/mbostock/d3/wiki/Time-Formatting

Get the latest commid ID in Get

To get the latest commid ID in Get,

use the following command:

$ git log --format="%H" -n 1

Reference:
http://stackoverflow.com/questions/19176359/how-to-get-the-last-commit-id-of-a-remote-repo-using-curl-like-command

Git rebase and squash commits

* Check commit logs as follows:

$ git log

commit da274bb605a962fa02ae8fba2da27b934b59d68d
Author: izeye <izeye@naver.com>
Date:   Tue Jul 28 11:55:38 2015 +0900

    Fix typos.

commit 0e5f855954a69dd05128442bf9c996efc8d35f0d
Author: izeye <izeye@naver.com>
Date:   Tue Jul 28 11:47:52 2015 +0900

    Fix typos.

commit 32128a6ac2390250d9e0b933618177846fb7bef0
Author: Stephane Nicoll <snicoll@pivotal.io>
Date:   Mon Jul 27 16:02:03 2015 +0200

    Polish
...

* `git rebase` with the base commit as follows:

$ git rebase -i 32128a6ac2390250d9e0b933618177846fb7bef0

pick 0e5f855 Fix typos.
squash da274bb Fix typos.

* Type `:wq` and change commit messages as follows:

# This is a combination of 2 commits.
# The first commit's message is:

Fix typos.

# This is the 2nd commit message:

#Fix typos.

* Type `:wq` again.

* Check commit logs again as follows:

$ git log

commit d51d6b7e8d21c60a6ac9e6e6e60847c112514998
Author: izeye <izeye@naver.com>
Date:   Tue Jul 28 11:47:52 2015 +0900

    Fix typos.

commit 32128a6ac2390250d9e0b933618177846fb7bef0
Author: Stephane Nicoll <snicoll@pivotal.io>
Date:   Mon Jul 27 16:02:03 2015 +0200

    Polish

If you want to push it to the remote repository,

do as follows:

$ git push -f

Reference:
https://github.com/edx/edx-platform/wiki/How-to-Rebase-a-Pull-Request

only buildscript {} and other plugins {} script blocks are allowed before plugins {} blocks, no other statements are allowed

You might encounter the following error:

only buildscript {} and other plugins {} script blocks are allowed before plugins {} blocks, no other statements are allowed

Just do the instruction in the error message.

In order words, move `plugin {}` script block on top of the script

except `buildscript {}` and other `plugins {}` script blocks.

Change Gradle version in IntelliJ

To change Gradle version in IntelliJ,

do as follows:

File -> Settings -> Gradle -> Gradle home

Format `yyyy-MM-dd HH:mm:ss` in Bash

To format `yyyy-MM-dd HH:mm:ss` in Bash,

do as follows:

date +"%F %T"

Uncaught RangeError: Maximum call stack size exceeded

I got the following error suddenly in Windows Chrome Canary:

Uncaught RangeError: Maximum call stack size exceeded

It didn't happen in Windows Chrome, Mac Chrome, and Mac Chrome Canary.

I guess it's a bug of Windows Chrome Canary.

I'm wondering why this kind of bug is happening.

I guess they have tons of tests.

Although it's quite easily reproducible, why did they miss it?

java.lang.NoClassDefFoundError: org/codehaus/groovy/runtime/typehandling/ShortTypeHandling

When I used the following command:

gradle build

I got the following exception:

FAILURE: Build failed with an exception.
             
* Where:    
Build file 'C:\Users\nbp\IdeaProjects\impression-neo\build.gradle' line: 101
             
* What went wrong:
Execution failed for task ':generateGitProperties'.
> java.lang.NoClassDefFoundError: org/codehaus/groovy/runtime/typehandling/ShortTypeHandling
             
* Try:      
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.
             
BUILD FAILED

When I checked the Gradle version with the following command:

gradle -v

the result was as follows:

------------------------------------------------------------
Gradle 1.11
------------------------------------------------------------

Build time:   2014-02-11 11:34:39 UTC
Build number: none
Revision:     a831fa866d46cbee94e61a09af15f9dd95987421

Groovy:       1.8.6
Ant:          Apache Ant(TM) version 1.9.2 compiled on July 8 2013
Ivy:          2.2.0
JVM:          1.8.0_05 (Oracle Corporation 25.5-b02)
OS:           Windows 7 6.1 amd64

When I upgraded Gradle to 2.5 as follows:

------------------------------------------------------------
Gradle 2.5
------------------------------------------------------------

Build time:   2015-07-08 07:38:37 UTC
Build number: none
Revision:     093765bccd3ee722ed5310583e5ed140688a8c2b

Groovy:       2.3.10
Ant:          Apache Ant(TM) version 1.9.3 compiled on December 23 2013
JVM:          1.8.0_05 (Oracle Corporation 25.5-b02)
OS:           Windows 7 6.1 amd64

the problem was solved.

I guess the problem was caused by the old version of Groovy.

Use Swagger in Spring Boot

To use Swagger in Spring Boot,

add the following dependencies to `build.gradle`:

    compile("io.springfox:springfox-swagger2:2.1.1")
    compile("io.springfox:springfox-swagger-ui:2.1.1")

and add `@EnableSwagger2` as follows:

@SpringBootApplication
@EnableSwagger2
public class Application {

public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}

}

Open the following URL in your browser:

http://localhost:8080/swagger-ui.html

Reference:
http://springfox.github.io/springfox/docs/current/

Spring Data JPA `IN` clause with Spring Data REST

You can do as follows:

http://localhost:8080/api/events/search/findByLevelIn?level=ERROR,WARN

See the following link for the details on Spring Data JPA `IN` clause:

http://izeye.blogspot.kr/2015/07/use-in-caluse-with-spring-data-jpa.html

Use `IN` clause with Spring Data JPA

To use `IN` clause with Spring Data JPA,

you can do as follows:

public interface EventRepository extends JpaRepository<Event, Long> {

  Page<Event> findByLevelIn(@Param("level") Set<EventLevel> levels, Pageable pageable);

}

You can test as follows:

  @Test
  public void testFindByLevelIn() {
    Set<EventLevel> levels = new HashSet<>();
    levels.add(EventLevel.ERROR);
    levels.add(EventLevel.WARN);
    levels.add(EventLevel.INFO);

    Page<Event> events = eventRepository.findByLevelIn(levels, new PageRequest(0, 100));
    events.forEach(System.out::println);
  }

Reference:
http://stackoverflow.com/questions/18987292/spring-crudrepository-findbyinventoryidslistlong-inventoryidlist-equivalen

sun.net.util.IPAddressUtil vs. org.apache.commons.validator.routines.InetAddressValidator

There are two IP address validation utils:

sun.net.util.IPAddressUtil
org.apache.commons.validator.routines.InetAddressValidator

I made some tests for both.

`IPAddressUtil` tests:

// NOTE:
// Got the following warning in Travis:
// warning: IPAddressUtil is internal proprietary API and may be removed in a future release
public class IPAddressUtilTests {

@Rule
public ExpectedException thrown = ExpectedException.none();

@Test
public void testIsIPv4LiteralAddress() {
assertTrue(IPAddressUtil.isIPv4LiteralAddress("1.2.3.0"));
assertTrue(IPAddressUtil.isIPv4LiteralAddress("1.2.3.4"));
assertTrue(IPAddressUtil.isIPv4LiteralAddress("1.2.3.255"));
assertFalse(IPAddressUtil.isIPv4LiteralAddress("1.2.3.256"));
assertFalse(IPAddressUtil.isIPv4LiteralAddress("1.2.3."));

// NOTE: They look weird but valid.
// See http://stackoverflow.com/questions/7550806/check-valid-ipv4-address-in-java
assertTrue(IPAddressUtil.isIPv4LiteralAddress("1.2.3"));
assertTrue(IPAddressUtil.isIPv4LiteralAddress("1.2"));
assertTrue(IPAddressUtil.isIPv4LiteralAddress("1"));

assertFalse(IPAddressUtil.isIPv4LiteralAddress(""));
assertFalse(IPAddressUtil.isIPv4LiteralAddress("::1"));

thrown.expect(NullPointerException.class);
IPAddressUtil.isIPv4LiteralAddress(null);
}

@Test
public void testIsIPv6LiteralAddress() {
assertTrue(IPAddressUtil.isIPv6LiteralAddress("::1"));
assertFalse(IPAddressUtil.isIPv6LiteralAddress("1.2.3.4"));
}

}

`InetAddressValidator` tests:

public class InetAddressValidatorTests {

InetAddressValidator validator = InetAddressValidator.getInstance();

@Test
public void testIsValidInet4Address() {
assertTrue(validator.isValidInet4Address("1.2.3.0"));
assertTrue(validator.isValidInet4Address("1.2.3.4"));
assertTrue(validator.isValidInet4Address("1.2.3.255"));
assertFalse(validator.isValidInet4Address("1.2.3.256"));
assertFalse(validator.isValidInet4Address("1.2.3."));
assertFalse(validator.isValidInet4Address("1.2.3"));
assertFalse(validator.isValidInet4Address("1.2"));
assertFalse(validator.isValidInet4Address("1"));
assertFalse(validator.isValidInet4Address(""));
assertFalse(validator.isValidInet4Address("::1"));
assertFalse(validator.isValidInet4Address(null));
}

@Test
public void testIsValidInet6Address() {
assertTrue(validator.isValidInet6Address("::1"));
assertFalse(validator.isValidInet6Address("1.2.3.4"));
}

}

As you can see the above tests,

they work differently.

Don't use `IPAddressUtil`.

I got the following warning from Travis builds when I used it:

warning: IPAddressUtil is internal proprietary API and may be removed in a future release

Reference AngularJS's `$scope` in Chrome's Console

To reference AngularJS's `$scope.events` in Chrome's Console,

select the target element in `Elements` tab and use the following in `Console` tab:

angular.element($0).scope().events

Reference:
http://stackoverflow.com/questions/13743058/how-to-access-the-angular-scope-variable-in-browsers-console

Run a specifc test in Gradle

To run a specific test in Gradle,

you can use the following command:

gradle test --tests *SomeTests.test

Reference:
http://stackoverflow.com/questions/22505533/how-to-run-a-one-test-class-only-on-gradle

Spring Data REST max page size 1000

When I tried to fetch 2000 entries in Spring Data REST,

I got only 1000 entries.

I didn't know the reason until I saw the following source:

https://github.com/spring-projects/spring-data-rest/blob/master/spring-data-rest-core/src/main/java/org/springframework/data/rest/core/config/RepositoryRestConfiguration.java

It is used in `HateoasPageableHandlerMethodArgumentResolver.enhance()` as follows:

builder.replaceQueryParam(sizePropertyName, pageable.getPageSize() <= getMaxPageSize() ? pageable.getPageSize()
: getMaxPageSize());

If you use Spring Boot and want to change the default value,

you can add the following property to `application.properties`:

spring.data.rest.max-page-size=10000

I didn't find any related documentation except the source.

In my case, it would be nice to have a warning when exceeding the max page size,

but in some cases, it could be irritating, I guess.

Apply `WebJarsResourceResolver` in Spring Boot

To apply `WebJarsResourceResolver` in Spring Boot,

add the following property to `application.properties`:

spring.resources.chain.enabled:true

and add the following dependency to `build.gradle`:

    compile("org.webjars:webjars-locator:0.26")
    compile("org.webjars:jquery:2.1.4")

Now you can use jQuery as follows in Thymeleaf templates:

    <script src="/webjars/jquery/jquery.min.js"></script>

How to exclude a file when publishing an artifact to Maven repository in Gradle

To exclude a `logback.xml` file when publishing an artifact to Maven repository in Gradle,

you can use the following configuration:

ext {
    artifactId = project.name
    artifactVersion = project.version
}

jar {
    baseName = artifactId
    version = artifactVersion
}

task commonJar(type: Jar) {
    baseName "test-common"
    from sourceSets.main.output
    exclude 'logback.xml'
}

publishing {
    repositories {
        maven {
            credentials {
                username "admin"
                password "1234"
            }
            url "http://repo.test.com:8080/repository/internal"
        }
    }

    publications {
        maven(MavenPublication) {
            groupId 'com.test'
            artifactId artifactId
            version artifactVersion

            artifact commonJar
        }
    }
}

Reference:
https://docs.gradle.org/current/userguide/publishing_maven.html

Check an environment variable having Spring profiles if a specific Spring profile is activated by a Bash script

When an environment variable having Spring profiles is as follows:

SPRING_PROFILE=test,something-else

you can check if `test` Spring profile is activated by using the following Bash script:

spring_active_profiles=(${SPRING_PROFILE//,/ })

spring_profile_test_activated=false
for spring_active_profile in ${spring_active_profiles[@]}
do
  if [ $spring_active_profile == "test" ]
  then
    spring_profile_test_activated=true
  fi
done

echo $spring_profile_test_activated
if [ "$spring_profile_test_activated" = true ]
then
  echo "Spring profile 'test' is activated."
fi

Configure Graphite with Dropwizard Metrics in Spring Boot

To configure Graphite with Dropwizard Metrics in Spring Boot,

add the following Java Config:

@Configuration
public class GraphiteConfig {

  @Autowired
  private MetricRegistry metricRegistry;

  @Value("${graphite.host}")
  private String graphiteHost;

  @Value("${graphite.port}")
  private int graphitePort;

  @PostConstruct
  public void initialize() {
    Graphite graphite = new Graphite(this.graphiteHost, this.graphitePort);
    GraphiteReporter reporter = GraphiteReporter.forRegistry(this.metricRegistry)
        .prefixedWith(NetworkUtils.HOSTNAME.replace(".", "_"))
        .convertRatesTo(TimeUnit.SECONDS)
        .convertDurationsTo(TimeUnit.MILLISECONDS)
        .filter(MetricFilter.ALL).build(graphite);
    reporter.start(1, TimeUnit.MINUTES);
  }

}

and add the following properties:

graphite.host=1.2.3.4
graphite.port=2003

Reference:
https://dropwizard.github.io/metrics/3.1.0/manual/graphite/

Install Graphite with Python 2.6.6 on CentOS 6.6

If you don't have pip, install it as follows:

sudo yum install python-pip

# Install Django
sudo pip install 'https://www.djangoproject.com/download/1.4.20/tarball/'

# Install django-tagging
sudo easy_install django-tagging==0.3.1

# Install Twisted
sudo pip install twisted

# Install pytz
sudo pip install pytz

# Install bitmap-fonts-compat
sudo yum install bitmap-fonts-compat

# Install Apache
sudo yum install httpd

# Install mod_wsgi
sudo yum install mod_wsgi

sudo vi /etc/httpd/conf.d/wsgi.conf

#LoadModule wsgi_module modules/mod_wsgi.so

# Install Graphite
sudo pip install https://github.com/graphite-project/ceres/tarball/master
sudo pip install whisper
sudo pip install carbon
sudo pip install graphite-web

# Configure Carbon
cd /opt/graphite/conf
sudo cp carbon.conf.example carbon.conf
sudo cp storage-schemas.conf.example storage-schemas.conf

# Run Carbon
sudo /opt/graphite/bin/carbon-cache.py start

tail -F /opt/graphite/storage/log/carbon-cache/carbon-cache-a/console.log

# Test Carbon
echo "local.random.diceroll 4 `date +%s`" | nc localhost 2003

tail -F /opt/graphite/storage/log/carbon-cache/carbon-cache-a/creates.log

05/07/2015 14:22:22 :: new metric local.random.diceroll matched schema default_1min_for_1day
05/07/2015 14:22:22 :: new metric local.random.diceroll matched aggregation schema default
05/07/2015 14:22:22 :: creating database file /opt/graphite/storage/whisper/local/random/diceroll.wsp (archive=[(60, 1440)] xff=None agg=None)

# Configure Graphite Webapp
sudo cp /opt/graphite/examples/example-graphite-vhost.conf /etc/httpd/conf.d/graphite.conf
sudo cp /opt/graphite/conf/graphite.wsgi.example /opt/graphite/conf/graphite.wsgi
sudo cp /opt/graphite/webapp/graphite/local_settings.py.example /opt/graphite/webapp/graphite/local_settings.py

sudo chown apache:apache /opt/graphite/storage/
sudo chown apache:apache /opt/graphite/storage/log/webapp/

sudo python /opt/graphite/webapp/graphite/manage.py syncdb

# Start Apache
sudo /sbin/service httpd start

tail -F /opt/graphite/storage/log/webapp/error.log

# Visit Graphite Webapp Using Web Browser
http://your-ip-address/

References:
http://graphite.readthedocs.org/en/latest/install.html
http://graphite.readthedocs.org/en/latest/install-pip.html
http://graphite.readthedocs.org/en/latest/config-carbon.html
http://graphite.readthedocs.org/en/latest/admin-carbon.html
https://gist.github.com/ashrithr/9224450

Install a specific version of package by easy_install

To install a specific version of package by easy_install,

you can use the following command:

sudo easy_install django-tagging==0.3.1

Reference:
https://gist.github.com/ashrithr/9224450

Show installed packages by pip

If you want to know whether `tagging` package is installed,

you can use the following command:

$ pip freeze | grep tagging                                                            
django-tagging==0.4
tagging==0.2.1
$

Reference:
https://pip.pypa.io/en/latest/reference/pip_freeze.html

Show the version of an installed package by pip

If you want to know the version of an installed package (say, `django-tagging`) by pip,

use the following command:

$ pip show django-tagging
---
Name: django-tagging
Version: 0.4
Location: /usr/lib/python2.6/site-packages
Requires:
$

Reference:
http://stackoverflow.com/questions/10214827/find-which-version-of-package-is-installed-with-pip

Show installed packages by yum

If you want to know whether `python-devel` package is installed,

you can use the following command:

$ yum list installed | grep python-devel
python-devel.x86_64                2.6.6-52.el6                      @update
$

Reference:
http://www.electrictoolbox.com/yum-list-installed-packages/

Install Django with Python 2.6.6

If you try the following command:

sudo pip install django

you might get some error.

With Python 2.6.6, you can use only 1.4 version of Django.

So you have to use the following command to install:

sudo pip install 'https://www.djangoproject.com/download/1.4.20/tarball/'

You can check if it's working as follows:

$ python
...
>>> import django
>>> print(django.get_version())                                                                                    
1.4.20
>>>

If you want to use greater than 1.4 version,

you should upgrade Python to at least 2.7.

References:
https://docs.djangoproject.com/en/1.8/intro/install/
https://docs.djangoproject.com/en/1.8/faq/install/
https://www.djangoproject.com/download/

[warn] module wsgi_module is already loaded, skipping

When you did the following for Graphite,

sudo cp /opt/graphite/examples/example-graphite-vhost.conf /etc/httpd/conf.d/graphite.conf

you will get the following warning:

httpd ()  : [Fri Jul 03 19:16:29 2015] [warn] module wsgi_module is already loaded, skipping

You should comment out the original WSGI configuration as follows:

sudo vi /etc/httpd/conf.d/wsgi.conf

#LoadModule wsgi_module modules/mod_wsgi.so

Reference:
http://stackoverflow.com/questions/12120057/module-wsgi-module-is-already-loaded-skipping

Apache error log location in CentOS

In CentOS, you can find Apache error log in the following location:

/var/log/httpd/error_log

Reference:
http://lists.centos.org/pipermail/centos/2008-January/049950.html

Install pip in CentOS

To install pip in CentOS, use the following command:

sudo yum install python-pip

Reference:
https://pip.pypa.io/en/latest/installing.html

Read `Map` by `ObjectMapper.readValue()`

If you try to do the following:

Map<String, String> metricsMap = objectMapper.readValue(response, Map.class);

you might encounter the following exception:

java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String

You can solve the problem by using `TypeReference` as follows:

  private final TypeReference<Map<String, String>> metricsType
      = new TypeReference<Map<String, String>>() {};

Map<String, String> metricsMap = objectMapper.readValue(response, metricsType);

`spring.data.rest.base-uri` doesn't work

After Spring Boot 1.3.0.M1, the following property doesn't work:

spring.data.rest.base-uri=/api

You have to use the following property:

spring.data.rest.base-path=/api

This is corresponding to Spring Data REST change.

Handle keys having dots in JsonPath

When you handle keys having dots in JsonPath,

you can use one of the followings:

// NOTE: 1L doesn't work. Why?
assertThat(JsonPath.<Long> read(metrics, "['counter.test']"), is(1));
assertThat(JsonPath.<Long> read(metrics, "$['counter.test']"), is(1));
assertThat(JsonPath.<Long> read(metrics, "$.['counter.test']"), is(1));

I'm not sure why `<Long>` doesn't work as expected.

It's converted into `Integer`.

You can see a sample in the following:

https://github.com/izeye/samples-spring-boot-branches/blob/rest-and-actuator/src/test/java/samples/springboot/counter/web/CounterControllerTests.java

Reference:
http://stackoverflow.com/questions/19726859/jsonpath-junit-escape-character-for-dots

Get detailed stack traces of failed tests in Gradle

When a test failed in Gradle,

you will get the following stack trace:

com.izeye.test.SomeTests > test FAILED
    java.lang.IllegalStateException                                                    
        Caused by: org.springframework.beans.factory.BeanCreationException              
            Caused by: java.lang.NoClassDefFoundError                                  
                Caused by: java.lang.ClassNotFoundException

But it's sometimes not useful.

When you want to get a detailed stack trace,

add the following configuration:

    test {
        testLogging {
            exceptionFormat = 'full'
        }
    }

Now you will get the following output:

com.izeye.test.SomeTests > test FAILED  
    java.lang.IllegalStateException: Failed to load ApplicationContext                  
                                                                                       
        Caused by:                                                                      
        org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlSessionFactory' defined in class path resource [com/izeye/test/config/PersistenceConfig.class]: Invocation of init method failed; nested exception is java.lang.NoClassDefF
oundError: org/w3c/dom/ElementTraversal
                                                                                       
            Caused by:                                                                  
            java.lang.NoClassDefFoundError: org/w3c/dom/ElementTraversal                
                                                                                       
                Caused by:                                                              
                java.lang.ClassNotFoundException: org.w3c.dom.ElementTraversal      

Now you can see that the culprit was `org.w3c.dom.ElementTraversal `.

Reference:
http://java.dzone.com/articles/gradle-goodness-show-more

Caused by: java.lang.NoSuchFieldException: $jacocoAccess

When you run the following command:

gradle clean test

you might get the following exception:

Caused by: java.lang.NoSuchFieldException: $jacocoAccess

JaCoCo default version (0.6.2.201302030002) doesn't work with Java 8.

You can check your JaCoCo version with the following configuration:

    jacoco {
        println toolVersion
    }

and you will get the following output:

0.6.2.201302030002

You can fix with the following configuration:

    jacoco {
        toolVersion = "0.7.1.201405082137"
    }

Reference:
https://github.com/jacoco/jacoco/issues/74

Missing `datasource.xxx.active` and `datasource.xxx.usage` in `metrics` endpoint in Spring Boot Actuator

In Spring Boot Actuator's `metrics` endpoint,

if you can't see `datasource.xxx.active` and `datasource.xxx.usage`,

you might have the following configuration:

@SpringBootApplication(exclude = {
    DataSourceAutoConfiguration.class,
    DataSourceTransactionManagerAutoConfiguration.class
})

Showing the metrics needs `DataSourcePoolMetadataProvidersConfiguration`

which is included in `DataSourceAutoConfiguration`.

So you have to use the following if you don't use `DataSourceAutoConfiguration`:

@Import(DataSourcePoolMetadataProvidersConfiguration.class)

It would be nice to separate them because `DataSourceAutoConfiguration` doesn't work

when having multiple `DataSource`s.

`java.lang.StackOverflowError` in Spring Data MongoDB

You might encounter the following error suddenly:

java.lang.StackOverflowError
at java.lang.String.<init>(String.java:201)
at java.lang.String.substring(String.java:1956)
at sun.reflect.misc.ReflectUtil.isNonPublicProxyClass(ReflectUtil.java:288)
at sun.reflect.misc.ReflectUtil.checkPackageAccess(ReflectUtil.java:165)
at sun.reflect.misc.ReflectUtil.isPackageAccessible(ReflectUtil.java:195)
at java.beans.MethodRef.get(MethodRef.java:72)
at java.beans.PropertyDescriptor.getReadMethod(PropertyDescriptor.java:206)
at org.springframework.data.mapping.model.AbstractPersistentProperty.getGetter(AbstractPersistentProperty.java:159)
at org.springframework.data.mapping.model.BeanWrapper.getProperty(BeanWrapper.java:127)
at org.springframework.data.mapping.model.BeanWrapper.getProperty(BeanWrapper.java:100)
at org.springframework.data.mongodb.core.convert.MappingMongoConverter$3.doWithPersistentProperty(MappingMongoConverter.java:419)
at org.springframework.data.mongodb.core.convert.MappingMongoConverter$3.doWithPersistentProperty(MappingMongoConverter.java:412)
at org.springframework.data.mapping.model.BasicPersistentEntity.doWithProperties(BasicPersistentEntity.java:307)
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.writeInternal(MappingMongoConverter.java:412)
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.writeInternal(MappingMongoConverter.java:386)
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.writeCollectionInternal(MappingMongoConverter.java:622)
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.createCollection(MappingMongoConverter.java:546)
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.writePropertyInternal(MappingMongoConverter.java:457)
at org.springframework.data.mongodb.core.convert.MappingMongoConverter$3.doWithPersistentProperty(MappingMongoConverter.java:424)
at org.springframework.data.mongodb.core.convert.MappingMongoConverter$3.doWithPersistentProperty(MappingMongoConverter.java:412)
at org.springframework.data.mapping.model.BasicPersistentEntity.doWithProperties(BasicPersistentEntity.java:307)

I didn't dig into the problem due to lack of time

but the culprit was `Logger` in a MongoDB document as follows:

  private final Logger log = LoggerFactory.getLogger(getClass());

It could be fixed with `org.springframework.data.annotation.Transient` as follows:

  @Transient
  private final Logger log = LoggerFactory.getLogger(getClass());

but it doesn't make sense that every document has its own field for the logger

although the logger will be singleton.

Using `static` is much better as follows:

  private static final Logger log = LoggerFactory.getLogger(NaboxImpressionLog.class);

Reference:
http://stackoverflow.com/questions/21734785/mongodb-spring-saving-an-object-causes-stackoverflowerror

Error:Cause: net.rubygrapefruit.platform.internal.jni.WindowsHandleFunctions.markStandardHandlesUninheritable(Lnet/rubygrapefruit/platform/internal/FunctionResult;)V

I encountered the following error in IntelliJ when I tried to run a Gradle task:

Error:Cause: net.rubygrapefruit.platform.internal.jni.WindowsHandleFunctions.markStandardHandlesUninheritable(Lnet/rubygrapefruit/platform/internal/FunctionResult;)V

I can run a Gradle task in a terminal but I can't run a Gradle task in IntelliJ any more.

I'll update if I find any.

Any hint to solve this problem will be appreciatied.

---

UPDATED:

Restarting IntelliJ solved the problem :-)

java.lang.IllegalArgumentException: Cannot locate declared field class org.apache.http.impl.client.HttpClientBuilder.sslcontext

When you try to use `HtmlUnit`,

you might encounter the following exception:

java.lang.IllegalArgumentException: Cannot locate declared field class org.apache.http.impl.client.HttpClientBuilder.sslcontext

You're using httpcomponents 4.5.

If you don't need the version,

downgrade it to 4.4.1 as follows:

    testCompile("org.apache.httpcomponents:httpclient:4.4.1")
    testCompile("org.apache.httpcomponents:httpmime:4.4.1")

References:
http://htmlunit.10904.n7.nabble.com/HtmlUnit-htmlunit-bugs-1692-Update-to-HttpComponents-4-5-td36318.html

Show all indexes in MongoDB

To show all indexes in MongoDB,

you can use the following command:

db.someCollection.getIndexes()

Reference:
http://docs.mongodb.org/manual/tutorial/list-indexes/

Relocate MongoDB storage location in CentOS

To relocate MongoDB storage location in CentOS,

stop MongoDB server with the following command:

sudo /sbin/service mongod stop

Modify MongoDB configuration as follows:

sudo vi /etc/mongod.conf

#dbpath=/var/lib/mongo
dbpath=/home/izeye/mongo

Start MongoDB server with the following command:

sudo /sbin/service mongod start

Note that the directory should be owned by `mongod` user.

If not, change it by the following command:

sudo chown mongod /home/izeye/mongo/

Caused by: com.mongodb.WriteConcernException: { "serverUsed" : "1.2.3.4:27017" , "ok" : 1 , "n" : 0 , "err" : "new file allocation failure" , "code" : 12520}

You might encounter the following exception:

Caused by: com.mongodb.WriteConcernException: { "serverUsed" : "1.2.3.4:27017" , "ok" : 1 , "n" : 0 , "err" : "new file allocation failure" , "code" : 12520}

You can check your MongoDB server log with the following command:

sudo vi /var/log/mongodb/mongod.log

The log will have the following lines:

2015-06-10T20:19:19.311+0900 I -        [conn7] Assertion: 12520:new file allocation failure
2015-06-10T20:19:19.313+0900 I STORAGE  [FileAllocator] allocating new datafile /var/lib/mongo/test.6, filling with zeroes...
2015-06-10T20:19:19.316+0900 I -        [conn7] Assertion: 12520:new file allocation failure
2015-06-10T20:19:19.316+0900 I STORAGE  [FileAllocator] FileAllocator: posix_fallocate failed: errno:28 No space left on device falling back
2015-06-10T20:19:19.317+0900 I STORAGE  [FileAllocator] error: failed to allocate new file: /var/lib/mongo/test.6 size: 2146435072 failure creating new datafile; lseek failed for fd 22 with errno: errno:2 No such file or directory.  will try again in 10 seconds
2015-06-10T20:19:19.322+0900 I -        [conn7] Assertion: 12520:new file allocation failure

You can notice there is not enough space.

So you can clean up your disk

or relocate MongoDB storage location

to a directory mounted on a different partition or disk.

Caused by: java.lang.NoClassDefFoundError: org/w3c/dom/ElementTraversal

You can encounter the following error after upgrading to Spring Boot 1.3.0.M1:

Caused by: java.lang.NoClassDefFoundError: org/w3c/dom/ElementTraversal
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:760)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:455)
at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:367)
at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:360)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at org.apache.xerces.parsers.AbstractDOMParser.startDocument(Unknown Source)
at org.apache.xerces.impl.dtd.XMLDTDValidator.startDocument(Unknown Source)
at org.apache.xerces.impl.XMLDocumentScannerImpl.startEntity(Unknown Source)
at org.apache.xerces.impl.XMLVersionDetector.startDocumentParsing(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
at org.apache.xerces.parsers.DOMParser.parse(Unknown Source)
at org.apache.xerces.jaxp.DocumentBuilderImpl.parse(Unknown Source)
at org.apache.ibatis.parsing.XPathParser.createDocument(XPathParser.java:254)
at org.apache.ibatis.parsing.XPathParser.<init>(XPathParser.java:125)
at org.apache.ibatis.builder.xml.XMLConfigBuilder.<init>(XMLConfigBuilder.java:75)
at org.mybatis.spring.SqlSessionFactoryBean.buildSqlSessionFactory(SqlSessionFactoryBean.java:358)
at org.mybatis.spring.SqlSessionFactoryBean.afterPropertiesSet(SqlSessionFactoryBean.java:340)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1637)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1574)

With the hint from StackOverflow and the following command:

gradle dependencies

I can figure out that `xml-apis-1.4.01` has been changed to `xml-apis-1.3.04` as follows:

Before upgrading to Spring Boot 1.3.0.M1:

+--- net.sourceforge.nekohtml:nekohtml:1.9.22
|    \--- xerces:xercesImpl:2.11.0
|         \--- xml-apis:xml-apis:1.4.01

After upgrading to Spring Boot 1.3.0.M1:

+--- net.sourceforge.nekohtml:nekohtml:1.9.22
|    \--- xerces:xercesImpl:2.11.0
|         \--- xml-apis:xml-apis:1.4.01 -> 1.3.04

With the following command:

gradle dependencyInsight --dependency xml-apis

you will get the following result:

:dependencyInsight                                                                                                                                              
xml-apis:xml-apis:1.3.04 (selected by rule)
                                 
xml-apis:xml-apis:1.4.01 -> 1.3.04
\--- xerces:xercesImpl:2.11.0    
     \--- net.sourceforge.nekohtml:nekohtml:1.9.22
          \--- compile

`spring-boot-dependencies` enforces `1.3.04` as follows:

<xml-apis.version>1.3.04</xml-apis.version>

You can resolve the problem by using `xml-apis:1.4.01` as follows:

compile("xml-apis:xml-apis:1.4.01")

I created a PR to upgrade `xml-apis as follows:

https://github.com/spring-projects/spring-boot/pull/3226

References:
http://stackoverflow.com/questions/10234201/appengine-error-java-lang-noclassdeffounderror-org-w3c-dom-elementtraversal
https://github.com/spring-projects/spring-boot/blob/master/spring-boot-dependencies/pom.xml

Error creating bean with name 'mbeanExporter' defined in class path resource [org/springframework/boot/autoconfigure/jmx/JmxAutoConfiguration.class]

When you have the following JMX configuration with Spring Boot,

  @Bean
  public MBeanServerFactoryBean mBeanServer() {
    MBeanServerFactoryBean mBeanServerFactoryBean = new MBeanServerFactoryBean();
    mBeanServerFactoryBean.setLocateExistingServerIfPossible(true);
    return mBeanServerFactoryBean;
  }

you can encounter the following exception:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'mbeanExporter' defined in class path resource [org/springframework/boot/autoconfigure/jmx/JmxAutoConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.jmx.export.annotation.AnnotationMBeanExporter]: Factory method 'mbeanExporter' threw exception; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'mbeanServer' is defined
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:599)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1119)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1014)

If you should keep your own `MBeanServer`,

set the following property in `application.properties`:

spring.jmx.server=mBeanServer

If you don't have to keep your own `MBeanServer`,

drop your own JMX configuration for `MBeanServer`

and use one provided by Spring Boot.

Reference:
http://docs.spring.io/spring-boot/docs/current-SNAPSHOT/reference/htmlsingle/

List all indexes in MongoDB

To list all indexes in MongoDB,

you can do the following:

> db.someCollection.getIndexes()                                                                                
[
        {
                "v" : 1,
                "key" : {
                        "_id" : 1
                },
                "name" : "_id_",
                "ns" : "test.someCollection"
        },
        {
                "v" : 1,
                "key" : {
                        "someIndexProperty" : 1
                },
                "name" : "someIndexProperty_1",
                "ns" : "test.someCollection"
        }
]
>

Reference:
http://docs.mongodb.org/manual/tutorial/list-indexes/

Create an index in MongoDB

To create an index in MongoDB,

you can do the following:

> db.someCollection.createIndex({someIndexProperty: 1})
{
        "createdCollectionAutomatically" : false,
        "numIndexesBefore" : 1,
        "numIndexesAfter" : 2,
        "ok" : 1
}
>

Reference:
http://docs.mongodb.org/manual/tutorial/create-an-index/

Oracle VARCHAR2's length is BYTE or CHAR?

Oracle VARCHAR2's length is BYTE or CHAR?

It depends on an option you used when creating a column as follows:

VARCHAR2(20 BYTE)

VARCHAR2(20 CHAR)

What if you omit the option as follows?

VARCHAR2(20)

It depends on the global setting for length semantics.

You can check the setting as follows:

SELECT VALUE FROM NLS_DATABASE_PARAMETERS WHERE PARAMETER = 'NLS_LENGTH_SEMANTICS';

BYTE

References:
http://docs.oracle.com/cd/B28359_01/server.111/b28318/datatype.htm#CNCPT1824
http://oracleschools.blogspot.kr/2013/01/how-to-check-nlslengthsemantics.html

How to use `sort` in Spring Data REST

To use `sort` in Spring Data REST,

you can use as follows:

http://localhost:{port}/api/customers?sort=firstName,desc

You can reference the following sample project:

https://github.com/izeye/samples-spring-boot-branches/tree/jpa-and-data-rest

Reference:
http://docs.spring.io/spring-data/rest/docs/current/reference/html/

MongoDB installation location in Windows

MongoDB installation location in Windows is as follows:

C:\Program Files\MongoDB\Server\3.0\bin

Allow all interfaces to listen for MongoDB in CentOS 6.6

To allow all interfaces to listen for MongoDB in CentOS 6.6,

comment out the `bind_ip` as follows:

sudo vi /etc/mongod.conf

# Listen to local interface only. Comment out to listen on all interfaces.
#bind_ip=127.0.0.1

Restart the MongoDB server (mongod) as follows:

sudo /sbin/service mongod start

Change MongoDB server port in CentOS 6.6

To change MongoDB server port in CentOS 6.6,

edit the following configuration:

sudo vi /etc/mongod.conf

port=10000

Restart the MongoDB server (mongod) as follows:

sudo /sbin/service mongod start

Reference:
http://docs.mongodb.org/manual/reference/configuration-options/

Install MongoDB on CentOS 6.6

To install MongoDB on CentOS 6.6,

you add MongoDB repository as follows:

sudo vi /etc/yum.repos.d/mongodb-org-3.0.repo

[mongodb-org-3.0]
name=MongoDB Repository
baseurl=http://repo.mongodb.org/yum/redhat/$releasever/mongodb-org/3.0/x86_64/
gpgcheck=0
enabled=1

Install MongoDB by `yum` as follows:

sudo yum install -y mongodb-org

Start MongoDB by `service` as follows:

sudo /sbin/service mongod start

Check listening port as follows:

sudo vi /var/log/mongodb/mongod.log

2015-06-08T21:14:23.908+0900 I NETWORK  [initandlisten] waiting for connections on port 27017

Run MongoDB client as follows:

mongo

Reference:
http://docs.mongodb.org/manual/tutorial/install-mongodb-on-red-hat/

java.lang.IllegalArgumentException: Cannot subclass final class class com.sun.proxy.$Proxy52

When you are using Spring Data MongoDB,

you can encounter the following exception:

Caused by: java.lang.IllegalArgumentException: Cannot subclass final class class com.sun.proxy.$Proxy52
at org.springframework.cglib.proxy.Enhancer.generateClass(Enhancer.java:446)
at org.springframework.cglib.transform.TransformingClassGenerator.generateClass(TransformingClassGenerator.java:33)

It happened by adding `@Repository` accidentally as follows:

@Repository
public interface SomethingRepository extends MongoRepository<Something, String> {
}

Removing `@Repository` fixes the problem.

It would be better to have an exception having better explanation if possible.

Reference:
https://github.com/spring-projects/spring-boot/issues/1929

Hotfix KB2731284 or later update is not installed, will zero-out data files

When you run a MongoDB server (mongod) in Windows,

you can encounter the following error:

C:\Program Files\MongoDB\Server\3.0\bin>mongod
2015-06-08T20:29:47.485+0900 I CONTROL  Hotfix KB2731284 or later update is not installed, will zero-out data files
2015-06-08T20:29:47.565+0900 I STORAGE  [initandlisten] exception in initAndListen: 29 Data directory C:\data\db\ not found., terminating
2015-06-08T20:29:47.565+0900 I CONTROL  [initandlisten] dbexit:  rc: 100

You can fix it by creating the following directory:

C:\data\db

Unfortunately I can't understand why it fixed the problem.

Anyone who explains why?

Reference:
http://stackoverflow.com/questions/29316482/mongo-error-on-i-control-hotfix

Show all sub-projects' dependencies in Gradle

In Gradle, to show all sub-projects' dependencies,

add the following to `build.gradle`.

subprojects {
    task allDependencies(type: DependencyReportTask) {}
}

Now you can use the following command:

gradle allDependencies

Reference:
https://solidsoft.wordpress.com/2014/11/13/gradle-tricks-display-dependencies-for-all-subprojects-in-multi-project-build/

Caused by: java.lang.NoSuchMethodError: org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry.hasMappingForPattern(Ljava/lang/String;)Z

You can encounter the following error:

Caused by: java.lang.NoSuchMethodError: org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry.hasMappingForPattern(Ljava/lang/String;)Z
at org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter.addResourceHandlers(WebMvcAutoConfiguration.java:256)
at org.springframework.web.servlet.config.annotation.WebMvcConfigurerComposite.addResourceHandlers(WebMvcConfigurerComposite.java:102)

Using `gradle dependencies` didn't help me much.

It showed the right dependency I expected:

org.springframework:spring-webmvc:4.1.6.RELEASE

It's one of Gradle sub-projects.

It is caused by another sub-project which it depends on.

The sub-project has a dependency having the following transitive dependency:

org.springframework.mobile:spring-mobile-device:1.1.3.RELEASE

And it has the following transitive dependency:

org.springframework:spring-webmvc:3.2.11.RELEASE

So the conflict occurred.

I solved it as follows:

    compile("xxx:xxx:1.0.0") {
        exclude module: 'spring-mobile-device'
    }

But I can't understand why the latest dependency doesn't win.