Skip to main content

Notice: this Wiki will be going read only early in 2024 and edits will no longer be possible. Please see: https://gitlab.eclipse.org/eclipsefdn/helpdesk/-/wikis/Wiki-shutdown-plan for the plan.

Jump to: navigation, search

Difference between revisions of "EclipseLink/Development/JPA 2.0/canonical model generation"

m (moved info to elug)
 
(21 intermediate revisions by 2 users not shown)
Line 5: Line 5:
  
 
==Issue Summary==
 
==Issue Summary==
With the new Criteria API from the JPA 2.0 spec, EclipseLink will provide a way to produce static metamodel classes corresponding to the entities, mapped superclasses, and embeddable classes in the persistence unit. A static metamodel class models the persistent state and relationships of the corresponding managed class.
+
With the new Criteria API from the JPA 2.0 spec, EclipseLink can now produce static metamodel classes that correspond to the entities, mapped superclasses, and embeddable classes in the persistence unit. A static metamodel class models the persistent state and relationships of the corresponding managed class.
  
For portability, EclipseLink will generate the canonical metamodel as defined in section 6.2.1.1.
+
For portability, EclipseLink generates this canonical metamodel as defined in section 6.2.1.1 of the specification.
  
 
==General solution==
 
==General solution==
EclipseLink will employ the annotation processor tool (APT) in conjunction with its existing metadata processing of annotations and XML to generate the static metamodel classes.
+
EclipseLink generates the static metamodel classes by using the the annotation processor tool (APT) in conjunction with its existing metadata processing of annotations.
  
 
For more information on APT, see: http://java.sun.com/j2se/1.5.0/docs/guide/apt/GettingStarted.html
 
For more information on APT, see: http://java.sun.com/j2se/1.5.0/docs/guide/apt/GettingStarted.html
  
== Metadata processing  ==
 
  
Internal processing details not available at this time ...
+
==End-user information==
 +
For additional information, see [[UserGuide/JPA/Using_the_Canonical_Model_Generator_(ELUG)|Using the Canonical Model Generator]] in the EclipseLink User Guide.
  
== Configuring and using within Eclipse Galileo  ==
 
 
The following steps outline how to configure the metamodel generation within the Eclipse IDE.
 
 
#Select '''Project''' - '''Properties'''
 
#Select '''Java Compiler''' and ensure you are using JDK 1.6+
 
#Expand '''Java Compiler''' and select '''Annotation Processing'''.
 
#On the right, select the checkbox '''Enable annotation processing'''
 
#In the text box for '''Generated Source Directory''' enter the name of the directory to which you would like to generate the metamodel classes
 
#By default, '''Processor options''' are not needed. However, EclipseLink provides you with custom generation options if you would like to configure you metamodel classes differently then defined in the spec. See the EclipseLink custom processor options section below for supported processor options.
 
#Expand '''Annotation Processing''' and select '''Factory Path'''
 
##Here you must add three libraries/jars for the processor to work (see 1.2.0 RC4 Library names below):
 
###The eclipselink.jar
 
###The java persistence 2.0 preview jar
 
###A special jar containing an enabling services file that specifies the name of the annotation processor tool.
 
 
Within Eclipse you should note that the annotation processor tool does not log to the '''Console''' window. The annotation processor tool logs and throws error messages on the '''Error Log''' window. To open this window, select '''Window''' - '''Show View''' - '''Error Log'''
 
 
== Configuring and using within ANT/javac  ==
 
 
#Add modelgen jar on javac classpath
 
#-processor option on javac command line
 
#Options here are specifies with using -A (e.g. javac -Aeclipselink.persistencexml=META-INF/sub/persistence.xml)
 
 
== EclipseLink custom processor options  ==
 
 
*'''eclipselink.persistencexml'''
 
 
This optional property specifies the full resource name to look for the persistence XML files in. If not specified the default META-INF/persistence.xml will be used.
 
 
*'''eclipselink.persistenceunits'''
 
 
This optional property specifies the set of persistence unit names that will be used when generating the canonical model. By default all persistence units available in all persistence XML files will be used. The value of this property is a comma separated list. When specifying multiple persistence units it is not possible to have persistence units with a comma in their name.
 
 
*'''eclipselink.canonicalmodel.prefix'''
 
 
This optional property specifies the prefix that will be added to the start of the class name of any canonical model class generated. By default the prefix is not used.
 
 
*'''eclipselink.canonicalmodel.suffix'''
 
 
This optional property specifies the suffix that will be added to the end of the class name of any canonical model class generated. By default the suffix value is "_". If this property is specified the value must be a non-empty string that contains valid characters for use in a Java class name.
 
 
*'''eclipselink.canonicalmodel.subpackage'''
 
 
This optional property specifies a sub-package name that can be used to have the canonical model generator generate its classes in a sub-package of the package where the corresponding entity class is located. By default the canonical model classes are generated into the same package as the entity classes.
 
 
== EclipseLink 1.2.0 RC4 Library names  ==
 
 
Currently the target release of EclipseLink 1.2.0 is RC4 which uses the following jar files names in the ZIP installer. Please note that the ZIP installer is the only distribution of EclipseLink including the modelgen JAR file.
 
 
#Services file (enables the processor) - '''''\eclipselink\jlib\jpa\eclipselink-jpa-modelgen_1.2.0.v20091016-r5565.jar'''''
 
#javax.persistence library - '''''\eclipselink\jlib\jpa\javax.persistence_2.0_preview.jar'''''
 
#EclipseLink jar -  '''''\eclipselink\jlib\eclipselink.jar'''''
 
 
== Troubleshooting  ==
 
 
After following the configuration steps above if no classes are generated, check the following.
 
 
#Ensure you have a persistence.xml. The default is META-INF/persistence.xml. If your persistence XML file is named differently or located elsewhere, you'll need to add the eclipselink.persistencexml processor option.
 
#If you are using an extended eclipselink orm mapping file and it is not listed in your persistence.xml file, it will not be discovered automatically (similar to the orm.xml file). You currently must specify <mapping-file>eclipselink-orm.xml</mapping-file> explicitly. The automatic discovery of the eclipselink-orm.xml if a known defect and will be corrected in a later version.
 
 
After an XML change (within Eclipse), the generated model classes are not updated to reflect the change
 
 
#Unlike changes to the model class itself, XML changes are not picked up automatically as the annotation processor is not aware of these changes. To have your XML changes reflected in your generated metamodel classes do a clean of your project. Select '''Project''' - '''Clean...'''
 
#If you have made many XML changes namely removed some mapping files or deleted some entities from others you will more than a project clean but rather a restart to the annotation processor tool to pick up all the changes. Do following to restart:
 
##Select '''Project''' - '''Properties'''
 
##Expand '''Java Compiler'''
 
##Select '''Annotation Processing''' and deselect the '''Enable annotation processing''' checkbox
 
##Click '''OK'''
 
##A window will present itself stating the annotation processing settings have changed and that a rebuild of the project is required for the changes to take effect. Click '''Yes'''
 
##Go back into the project propertes and select the '''Enable annotation processing''' checkbox.
 
##Same message from step #5 will present itself, click '''Yes'''
 
  
 
== Work schedule  ==
 
== Work schedule  ==

Latest revision as of 13:30, 23 October 2009

Canonical model generation

JPA 2.0 Root | bug 267391

Discussion

Issue Summary

With the new Criteria API from the JPA 2.0 spec, EclipseLink can now produce static metamodel classes that correspond to the entities, mapped superclasses, and embeddable classes in the persistence unit. A static metamodel class models the persistent state and relationships of the corresponding managed class.

For portability, EclipseLink generates this canonical metamodel as defined in section 6.2.1.1 of the specification.

General solution

EclipseLink generates the static metamodel classes by using the the annotation processor tool (APT) in conjunction with its existing metadata processing of annotations.

For more information on APT, see: http://java.sun.com/j2se/1.5.0/docs/guide/apt/GettingStarted.html


End-user information

For additional information, see Using the Canonical Model Generator in the EclipseLink User Guide.


Work schedule

  1. Development: 4 weeks
  1. Testing: 1 week

Back to the top