Vladimir V. Bychkov created TAP5-2749:
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Summary: Incorrect behavior of getIfExists in
EntityApplicationStatePersistenceStrategy
Key: TAP5-2749
URL: https://issues.apache.org/jira/browse/TAP5-2749
Project: Tapestry 5
Issue Type: Bug
Components: tapestry-jpa
Affects Versions: 5.5.0
Reporter: Vladimir V. Bychkov
+Error description+
Test [project
demonstrates|https://github.com/bvfalcon/tapestry-entity-state-test] an error
which was added during optimization TAP5-2478.
Methods
[get|https://github.com/apache/tapestry-5/blob/5.8.2/tapestry-core/src/main/java/org/apache/tapestry5/services/ApplicationStateManager.java#L57]
and
[getIfExists|https://github.com/apache/tapestry-5/blob/5.8.2/tapestry-core/src/main/java/org/apache/tapestry5/services/ApplicationStateManager.java#L67]
in ApplicationStateManager work different for JPA-Entities: first works
correct, second gives ClassCastException.
+Reason+
By invoking
[ApplicationStateManager.set|https://github.com/apache/tapestry-5/blob/5.8.2/tapestry-core/src/main/java/org/apache/tapestry5/services/ApplicationStateManager.java#L87]
method EntityApplicationStatePersistenceStrategy.set is used, which
[*transforms*|https://github.com/apache/tapestry-5/blob/5.8.2/tapestry-jpa/src/main/java/org/apache/tapestry5/internal/jpa/EntityApplicationStatePersistenceStrategy.java#L70]
instanceof Entity-class to instance of PersistedEntity Class.
By Invoking ApplicationStateManager.get method
EntityApplicationStatePersistenceStrategy.get is used, which
[*transforms*|https://github.com/apache/tapestry-5/blob/5.8.2/tapestry-jpa/src/main/java/org/apache/tapestry5/internal/jpa/EntityApplicationStatePersistenceStrategy.java#L44]
instanceof PersistedEntity Class back to Entity-class. Therefore [this
code|https://github.com/bvfalcon/tapestry-entity-state-test/blob/master/src/main/java/org/apache/tapestry/components/Layout.java#L14]
works correct.
By Invoking ApplicationStateManager.getIfExists method
SessionApplicationStatePersistenceStrategy.getIfExists is used
(SessionApplicationStatePersistenceStrategy is a superclass for
EntityApplicationStatePersistenceStrategy), which
[*casts*|https://github.com/apache/tapestry-5/blob/5.8.2/tapestry-core/src/main/java/org/apache/tapestry5/internal/services/SessionApplicationStatePersistenceStrategy.java#L75]
instanceof PersistedEntity Class to Entity-class. This is incorrect and gives
ClassCastException in [this
code|https://github.com/bvfalcon/tapestry-entity-state-test/blob/master/src/main/java/org/apache/tapestry/components/Layout.java#L15].
In other words, get makes back transformation, getIfExists - not. This is the
root of problem.
+Fix proposal+
The best solution IMHO will be [restore
getIfExists|https://github.com/apache/tapestry-5/blob/5.5.0/tapestry-core/src/main/java/org/apache/tapestry5/services/ApplicationStatePersistenceStrategy.java#L57]
in EntityApplicationStatePersistenceStrategy, may be with some optimizations
from TAP5-2478.
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