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flowable / flowable-engine

A compact and highly efficient workflow and Business Process Management (BPM) platform for developers, system admins and business users.
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Engine: JPA entity proxy object cannot be used as a process variable #1806

Open mwerlitz opened 5 years ago

mwerlitz commented 5 years ago

When using the JPA integration it is possible to use the entities as process variables e.g. in a multi-instance loop. The JPA provider may return a proxy object for the real entity e.g. for lazy loading in one-to-may collections.

Flowables way to get the Id of the entity object via reflection (at least for field access) for storing it as a process variable in JPAEntityMappings.getIdValue(Object value, EntityMetaData metaData) is broken when proxy objects are used. Tested with Hibernate 5.3.10 bundled with Spring Boot 2.1.5.

Tested with Flowable 6.4.1

Example Exception:

org.flowable.common.engine.api.FlowableIllegalArgumentException: Value of primary key for JPA-Entity cannot be null
at org.flowable.variable.service.impl.types.JPAEntityMappings.getIdString(JPAEntityMappings.java:168) ~[flowable-variable-service-6.4.1.jar:6.4.1]
at org.flowable.variable.service.impl.types.JPAEntityMappings.getJPAIdString(JPAEntityMappings.java:87) ~[flowable-variable-service-6.4.1.jar:6.4.1]
at org.flowable.variable.service.impl.types.JPAEntityVariableType.setValue(JPAEntityVariableType.java:72) ~[flowable-variable-service-6.4.1.jar:6.4.1]
at org.flowable.variable.service.impl.persistence.entity.VariableInstanceEntityImpl.setValue(VariableInstanceEntityImpl.java:139) ~[flowable-variable-service-6.4.1.jar:6.4.1]
at org.flowable.variable.service.impl.persistence.entity.VariableInstanceEntityManagerImpl.create(VariableInstanceEntityManagerImpl.java:50) ~[flowable-variable-service-6.4.1.jar:6.4.1]
at org.flowable.variable.service.impl.persistence.entity.VariableScopeImpl.createVariableInstance(VariableScopeImpl.java:887) ~[flowable-variable-service-6.4.1.jar:6.4.1]
at org.flowable.engine.impl.persistence.entity.ExecutionEntityImpl.createVariableInstance(ExecutionEntityImpl.java:720) ~[flowable-engine-6.4.1.jar:6.4.1]
at org.flowable.engine.impl.persistence.entity.ExecutionEntityImpl.createVariableLocal(ExecutionEntityImpl.java:741) ~[flowable-engine-6.4.1.jar:6.4.1]
at org.flowable.engine.impl.persistence.entity.ExecutionEntityImpl.setVariableLocal(ExecutionEntityImpl.java:684) ~[flowable-engine-6.4.1.jar:6.4.1]
at org.flowable.engine.impl.persistence.entity.ExecutionEntityImpl.setVariableLocal(ExecutionEntityImpl.java:664) ~[flowable-engine-6.4.1.jar:6.4.1]
at org.flowable.variable.service.impl.persistence.entity.VariableScopeImpl.setVariableLocal(VariableScopeImpl.java:737) ~[flowable-variable-service-6.4.1.jar:6.4.1]
at org.flowable.engine.impl.bpmn.behavior.MultiInstanceActivityBehavior.setLoopVariable(MultiInstanceActivityBehavior.java:401) ~[flowable-engine-6.4.1.jar:6.4.1]
at org.flowable.engine.impl.bpmn.behavior.MultiInstanceActivityBehavior.executeOriginalBehavior(MultiInstanceActivityBehavior.java:319) ~[flowable-engine-6.4.1.jar:6.4.1]
at org.flowable.engine.impl.bpmn.behavior.ParallelMultiInstanceBehavior.createInstances(ParallelMultiInstanceBehavior.java:86) ~[flowable-engine-6.4.1.jar:6.4.1]
at org.flowable.engine.impl.bpmn.behavior.MultiInstanceActivityBehavior.execute(MultiInstanceActivityBehavior.java:115) ~[flowable-engine-6.4.1.jar:6.4.1]

It looks like the field was identified, but its value via reflection is null, although calling a getter for the id on the object will return the correct value.

JPA 2.0 introduced a generic API for getting the identifier of an entity object via: entityManagerFactory.getPersistenceUnitUtil().getIdentifier(value)

Maybe this API should be used instead of reflection.

mwerlitz commented 5 years ago

Created a pull request with a test case: https://github.com/flowable/flowable-engine/pull/1808

mwerlitz commented 5 years ago

Created a pull request with a bugfix proposal: https://github.com/flowable/flowable-engine/pull/1809