[hibernate-issues] [Hibernate-JIRA] Created: (HV-443) Scope of ConstraintDescriptors sometimes wrong in type hierarchies

[Gunnar Morling (JIRA)]

Scope of ConstraintDescriptors sometimes wrong in type hierarchies
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                 Key: HV-443
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HV-443
             Project: Hibernate Validator
          Issue Type: Bug
          Components: engine
    Affects Versions: 4.1.0.Final
            Reporter: Gunnar Morling
             Fix For: 4.2.0.CR1


Using the BV meta data API it is possible to retrieve meta information on the constraints of given Java types. Using the {{ConstraintFinder}} API the scope of the constraints to retrieve meta data for can be restricted. 

Due to the caching of meta data in {{BeanMetaDataCache}} it can happen under certain circumstances that constraints are declared in scope {{LOCAL_ELEMENT}}, although it should be {{HIERARCHY}} instead.

The following test demonstrates the bug:

{code:java}
public class CacheTest {

  @Test
  public void constraintsFromSuperTypeAreInLocalScopeWhenSuperTypeIsLoadedFromCache() {

    Validator validator = Validation.buildDefaultValidatorFactory().getValidator();

    // loads BeanMetaData for A and puts it into the BeanMetaDataCache
    PropertyDescriptor propertyDescriptorForSuperType = validator
        .getConstraintsForClass(A.class).getConstraintsForProperty("foo");

    Set<ConstraintDescriptor<?>> constraintDescriptorsFromSuperType = propertyDescriptorForSuperType
        .findConstraints().lookingAt(Scope.LOCAL_ELEMENT)
        .getConstraintDescriptors();

    assertEquals(constraintDescriptorsFromSuperType.size(), 1);

    // re-uses BeanMetaData for A from cache, keeps A's constraints in
    // LOCAL_ELEMENT scope
    PropertyDescriptor propertyDescriptorForSubType = validator
        .getConstraintsForClass(B.class).getConstraintsForProperty("foo");

    Set<ConstraintDescriptor<?>> constraintDescriptorsFromSubType = propertyDescriptorForSubType
        .findConstraints().lookingAt(Scope.LOCAL_ELEMENT)
        .getConstraintDescriptors();

    // fails
    assertEquals(constraintDescriptorsFromSubType.size(), 0, "No descriptor in LOCAL scope expected for B.foo");
  }

  @Test
  public void constraintsFromSuperTypeAreInHierarchyScopeWhenSuperTypeIsNotLoadedFromCache() {

    Validator validator = Validation.buildDefaultValidatorFactory().getValidator();

    // loads BeanMetaData for A when traversing B's hierarchy, A's constraints
    // are correctly in HIERARCHY scope
    PropertyDescriptor propertyDescriptorForSubType = validator
        .getConstraintsForClass(B.class).getConstraintsForProperty("foo");

    Set<ConstraintDescriptor<?>> constraintDescriptorsFromSubType = propertyDescriptorForSubType
        .findConstraints().lookingAt(Scope.LOCAL_ELEMENT)
        .getConstraintDescriptors();

    assertEquals(constraintDescriptorsFromSubType.size(), 0, "No descriptor in LOCAL scope expected for B.foo");

    constraintDescriptorsFromSubType = propertyDescriptorForSubType
        .findConstraints().lookingAt(Scope.HIERARCHY)
        .getConstraintDescriptors();

    assertEquals(constraintDescriptorsFromSubType.size(), 1, "One descriptor in HIERARCHY scope expected for B.foo");
  }

  public static class A {

    @NotNull
    public String getFoo() {
      return null;
    }
  }

  public static class B extends A {
  }
}
{code}

The bug is caused by retrieving the meta data for {{A}} from the cache when building the meta data for its sub-type {{B}} (see {{constraintsFromSuperTypeAreInLocalScopeWhenSuperTypeIsLoadedFromCache}}). In this case the constraint from {{A}} are added to {{B}} but remain in scope {{LOCAL_ELEMENT}}. 

The bug does not occur when the meta data for {{A}} is retrieved when traversing the type hierarchy while building up the meta data for {{B}} (see {{constraintsFromSuperTypeAreInHierarchyScopeWhenSuperTypeIsNotLoadedFromCache}}), though I guess the constraints would be wrongly in scope {{HIERARCHY}} if afterwards the descriptors for {{A}} itself would be retrieved.

To fix this bug the constraint scope needs to be re-determined always if the meta data is retrieved from the cache.

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