/**
* Locates the entity manager field that should be used.
*
* <p>If a parent is defined, it must provide the field.
*
* <p>We generally expect the field to be named "entityManager" and be of type
* javax.persistence.EntityManager. We also require it to be public or protected, and annotated
* with @PersistenceContext. If there is an existing field which doesn't meet these latter
* requirements, we add an underscore prefix to the "entityManager" name and try again, until such
* time as we come up with a unique name that either meets the requirements or the name is not
* used and we will create it.
*
* @return the entity manager field (never returns null)
*/
public FieldMetadata getEntityManagerField() {
if (parent != null) {
// The parent is required to guarantee this is available
return parent.getEntityManagerField();
}
// Need to locate it ourself
int index = -1;
while (true) {
// Compute the required field name
index++;
final JavaSymbolName fieldSymbolName =
new JavaSymbolName(StringUtils.repeat("_", index) + "entityManager");
final FieldMetadata candidate = governorTypeDetails.getField(fieldSymbolName);
if (candidate != null) {
// Verify if candidate is suitable
if (!Modifier.isPublic(candidate.getModifier())
&& !Modifier.isProtected(candidate.getModifier())
&& (Modifier.TRANSIENT != candidate.getModifier())) {
// Candidate is not public and not protected and not simply a transient field (in which
// case subclasses
// will see the inherited field), so any subsequent subclasses won't be able to see it.
// Give up!
continue;
}
if (!candidate.getFieldType().equals(ENTITY_MANAGER)) {
// Candidate isn't an EntityManager, so give up
continue;
}
if (MemberFindingUtils.getAnnotationOfType(candidate.getAnnotations(), PERSISTENCE_CONTEXT)
== null) {
// Candidate doesn't have a PersistenceContext annotation, so give up
continue;
}
// If we got this far, we found a valid candidate
return candidate;
}
// Candidate not found, so let's create one
final List<AnnotationMetadataBuilder> annotations =
new ArrayList<AnnotationMetadataBuilder>();
final AnnotationMetadataBuilder annotationBuilder =
new AnnotationMetadataBuilder(PERSISTENCE_CONTEXT);
if (StringUtils.hasText(crudAnnotationValues.getPersistenceUnit())) {
annotationBuilder.addStringAttribute("unitName", crudAnnotationValues.getPersistenceUnit());
}
annotations.add(annotationBuilder);
final FieldMetadataBuilder fieldBuilder =
new FieldMetadataBuilder(
getId(), Modifier.TRANSIENT, annotations, fieldSymbolName, ENTITY_MANAGER);
return fieldBuilder.build();
}
}
