Develop Reference

How to implement JPA in Play Framework in a standard way

I have gone though https://www.playframework.com/documentation/2.5.x/JavaJPA
But it doesn't feel like a stardard way. I would like fill my jdbc connection in persistence.xml instead of application.conf
like this
<?xml version="1.0" encoding="UTF-8" ?>
<persistence xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
version="2.0" xmlns="http://java.sun.com/xml/ns/persistence">
<persistence-unit name="TestPersistence"
transaction-type="RESOURCE_LOCAL">
<class>com.example.pojo.Employee</class>
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
<non-jta-data-source>DefaultDS</non-jta-data-source>
<properties>
<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />
<property name="javax.persistence.jdbc.url"
value="jdbc:mysql://localhost:3306/jpadb" />
<property name="javax.persistence.jdbc.user" value="root" />
<property name="javax.persistence.jdbc.password"
value="mukesh" />
<!-- EclipseLink should create the database schema automatically -->
<property name="eclipselink.ddl-generation" value="create-tables" />
<property name="eclipselink.ddl-generation.output-mode"
value="database" />
</properties>
</persistence-unit>
</persistence>
instead of filling the jdbc connection in application.conf like
db.default.driver=com.mysql.jdbc.Driver
db.default.url="jdbc:mysql://localhost:3306/jpadb"
db.default.user=root
db.default.password="mukesh"
db.default.jndiName=DefaultDS
jpa.default=TestPersistence
Also if there is no other way to get jdbc connection in persistence.xml how can we define more than one jdbc connection in application.conf. like if i have a mysql for users and oracle db for posts.
NOTE: the source code posted are just dummy copied from public domain to show the briefly problem.

You don't have to use Play's DB module. You can have your own module defined, and load your database connection and run it in isolation.
I would check out https://github.com/playframework/play-isolated-slick as an example -- here the UserDAO is bound through to SlickDAO in the Play module:
https://github.com/playframework/play-isolated-slick/blob/master/modules/play/app/Module.scala#L19
and the database provider is provided:
https://github.com/playframework/play-isolated-slick/blob/master/modules/play/app/Module.scala#L27
but you don't have to use Database.forConfig("myapp.database") -- you can define any config you feel like.

Play application dies in idle state, restart on new request?

I am using HikariCp, Hibernate with my playframework application in java. After few mins of idle state, it seems play application dies, and when it gets new request it starts again. Sometime I have also seen Db persistence error with message that sessionfactory not available, which I believe is side-effect of this issue. Why application dies in idle state, and can I some how configure it to not do so ?
I get following logs, after every new requests in few mins of idle time -
[info] application - Application shutdown...
[info] application - Stopping HikariCP connection pool...
[info] application - Starting HikariCP connection pool...
Persistence.xml :-
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
version="2.0">
<persistence-unit name="defaultPersistenceUnit" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect"/>
<property name="hibernate.show_sql" value="true"/>
<property name="hibernate.format_sql" value="true"/>
<property name="hibernate.use_sql_comments" value="true"/>
<property name="hibernate.logSql" value="true"/>
<property name="hibernate.connection.provider_class" value="com.zaxxer.hikari.hibernate.HikariConnectionProvider"/>
<property name="hibernate.hikari.dataSourceClassName" value="com.impossibl.postgres.jdbc.PGDataSource"/>
</properties>
</persistence-unit>
</persistence>
Application.conf:-
# JPA configuration
# ~~~~~
# You can declare as many Ebean servers as you want.
# By convention, the default server is named `default`
jpa.default=defaultPersistenceUnit
# Assets configuration
# ~~~~~
"assets.cache./public/stylesheets/bootstrap.min.css"="max-age=360000"
# Logger
# ~~~~~
# You can also configure logback (http://logback.qos.ch/), by providing a logger.xml file in the conf directory .
# Root logger:
logger=ERROR
# Logger used by the framework:
logger.play=INFO
# Logger provided to your application:
logger.application=DEBUG
Thanks !

Your database connection provider when is iddle don´t do anything for re-connect, you will need indicate to your provider what to do in this case, for example:
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
version="2.0">
<persistence-unit name="defaultPersistenceUnit" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect"/>
<property name="hibernate.show_sql" value="true"/>
<property name="hibernate.format_sql" value="true"/>
<property name="hibernate.use_sql_comments" value="true"/>
<property name="hibernate.logSql" value="true"/>
<property name="hibernate.connection.provider_class" value="com.zaxxer.hikari.hibernate.HikariConnectionProvider"/>
<property name="hibernate.hikari.dataSourceClassName" value="com.impossibl.postgres.jdbc.PGDataSource"
<property name="hibernate.hikari.timeBetweenEvictionRunsMillis="30000" />
<property name="hibernate.hikari.minEvictableIdleTimeMillis="60000"/>
<property name="hibernate.hikari.removeAbandonedOnBorrow="true" /> <property name="hibernate.hikari.removeAbandonedOnMaintenance="true" />
<property name="hibernate.hikari.maxActive="30" />
<property name="hibernate.hikari.maxIdle="10" />
<property name="hibernate.hikari.maxWait="10000" />
<property name="hibernate.hikari.initialSize="5" />
<property name="hibernate.hikari.validationQuery= "SELECT 1" />
<property name="hibernate.hikari.validationInterval="30000" />
<property name="hibernate.hikari.removeAbandoned="true" />
<property name="hibernate.hikari.removeAbandonedTimeout="60" />
<property name="hibernate.hikari.logAbandoned="true"/>
</properties>
</persistence-unit>
</persistence>
check this link https://github.com/brettwooldridge/HikariCP/wiki/Bad-Behavior:-Handling-Database-Down

The reason behind this might be the connections are closed by database and so when the application tries to query on those connections sessionFactory is not available and it will throw exception.
I have faced similar issues in past and the only difference is I was using the c3p0 connection pool. So try setting the connectionTestQuery and idleTimeout property for your connection provider.
You may refer to this answer

JPA persistence.xml file content details

I am new to Java EE and JPA world, and need help with understanding persistence.xml file content. I work with Eclipse IDE, TomEE application server, OpenJPA as persistence provider, and MySQL as database.
Now, lets say I have some Java EE project with annotated entities named A,B and C, and I would like to map these entities to MySQL database named TestDB. I would like for database to be created during deployment, according to entity annotations. On MySQL server I log as "root" user with password "123".
Which properties from persistence.xml correspond to which Java EE environment artifacts (what represents persistence unit, where to specify database name ...)? Is this the correct persistence.xml file content, for situation described above:
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0"
xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
<persistence-unit name="Test" transaction-type="JTA">
<provider>org.apache.openjpa.persistence.PersistenceProviderImpl</provider>
<properties>
<property name="openjpa.ConnectionURL" value="jdbc:mysql://localhost:3306/TestDB" />
<property name="openjpa.ConnectionDriverName" value="com.mysql.jdbc.Driver" />
<property name="openjpa.ConnectionUserName" value="root" />
<property name="openjpa.ConnectionPassword" value="123" />
<property name="openjpa.jdbc.SynchronizeMappings" value="buildSchema(ForeignKeys=true)" />
<property name="openjpa.jdbc.DBDictionary" value="mysql" />
<property name="openjpa.Log" value="DefaultLevel=WARN, Tool=INFO" />
</properties>
</persistence-unit>
</persistence>
What else settings are important for JPA to work properly?
(Appreciate any help)

Above persistence.xml is missing datasource tag:
<jta-data-source>TestDB-jta-DS</jta-data-source>
Then, for Apache TomEE, data source can be defined in [tomee]/conf/tomee.xml configuration file. So, proper datasource definition for above persistence.xml would be:
<Resource id="TestDB-jta-DS" type="DataSource">
JdbcDriver com.mysql.jdbc.Driver
JdbcUrl jdbc:mysql://127.0.0.1:3306/TestDB
UserName root
Password 123
JtaManaged true
DefaultAutoCommit false
</Resource>

Hibernate and Glassfish config

I'm working on project(REST) where I use hibernate with glassfish. I try to get list of data from DB, but I get this error:
javax.persistence.PersistenceException: Exception [EclipseLink-4021] (Eclipse Persistence Services - 2.0.1.v20100213-r6600): org.eclipse.persistence.exceptions.DatabaseException
Exception Description: Unable to acquire a connection from driver [null], user [null] and URL [null]. Verify that you have set the expected driver class and URL. Check your login, persistence.xml or sessions.xml resource. The jdbc.driver property should be set to a class that is compatible with your database platform
note The full stack traces of the exception and its root causes are available in the GlassFish Server Open Source Edition 3.0.1 logs.
PERSISTENCE.XML
<?xml version="1.0" encoding="UTF-8" ?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"
version="1.0">
<persistence-unit name="manager1"
transaction-type="RESOURCE_LOCAL">
<properties>
<property name="hibernate.show_sql" value="false" />
<property name="hibernate.format_sql" value="false" />
<property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver" />
<property name="hibernate.connection.url"
value="jdbc:mysql://url" />
<property name="hibernate.connection.username" value="admin" />
<property name="hibernate.connection.password" value="admin" />
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
<property name="hibernate.hbm2ddl.auto" value="create-update" />
UPDATE:
Connection to hibernate works, because I tested it in console.
Is it possible that Hibernate requires another config file for hibernate?
Thanks for help :)

Environment specific Persistence xml in java standalone application

I have a standalone java application, which uses JPA for its persistence.
Right now I have a persistence.xml in META-INF.My application is currently in development.
My question is that if I move from development to the next envirnoment, say QA. I have to modify the persistence.xml and rebuild the jar. Is this the right way to go about it ?
If not,if I move the connection properties to a different file, where should this file be placed?
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd" version="2.0">
<persistence-unit name="pu1" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<class>ClassA</class>
<class>ClassB</class>
<class>ClassC</class>
<class>ClassD</class>
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.Oracle9Dialect" />
<property name="hibernate.connection.driver_class" value="oracle.jdbc.OracleDriver" />
<property name="hibernate.show_sql" value="true" />
<property name="hibernate.connection.username" value="username" />
<property name="hibernate.connection.password" value="password" />
<property name="hibernate.connection.url"
value="url" />
<property name="hibernate.max_fetch_depth" value="3" />
<property name="hibernate.archive.autodetection" value="class" />
</properties>
</persistence-unit>
</persistence>
Thanks in advance !

That's a good question. Normally, you put all these environment settings in an external file, say application.properties, and pass the location to it to the JVM when you start your application (e.g. -Dconfig.location=/conf/)
Then you should find a way to get the externalized properties into your EntityManagerFactory. You can't do that in persistence.xml, you can only hard-code things there. But you can do it when creating the entity manager factory by passing vendor properties.
If using a framework like spring, for example, this is easier to do, as spring provides a factory bean for the entity manager. Otherwise you should handle it yourself. Here's the relevant bit from spring:
provider.createEntityManagerFactory(persistenceUnitInfo, getJpaPropertyMap())