6:12 a.m.
As a user I would not expect the @Access annotation to be treated as a
special case by the framework in terms of when an annotation is
ignored, as for example that I can put this on either properties or
fields, and it would not be ignored, while other annotations could be
ignored depending on the position.
Also I highly doubt that there is a practical use case to "comment" a
mapping annotation by moving it to the wrong position (say I move a
@GeneratedValue from a field to a property when using FIELD access):
that would be extremely confusing to maintain.
The spec's wording states "When Access(PROPERTY) is applied to an
[...] mapping annotations **may** be placed on .."
I'd stress that it doesn' t say "must" but "may", and also
doesn't
seem to strictly ban the opposite.
As a user if I put a mapping annotation anywhere I expect it to be
respected, so I would expect the framework to work on the union of the
possible positions, and probably even to throw an exception on
conflicting options. The @Access property would then only be used to
state which access strategy should be used (and a nice effect is tha
the name becomes particularly self-explanatory too).
Also there are many types of possible contradictions in the mapping options:
public class Course {
@Id @GeneratedValue(strategy=TABLE)
private long id;
...
@Id @GeneratedValue(strategy=SEQUENCE)
public long getId() {
return id;
}
Or you could have a stronger conflict which isn't solvable via
AccesType "rules" either:
public class Course {
@Id @GeneratedValue(strategy=TABLE)
@Access(AccessType.FIELD)
private long id;
...
@Id @GeneratedValue(strategy=SEQUENCE)
@Access(AccessType.PROPERTY)
public long getId() {
return id;
}
This last example is the reason why I think you should always
consistently look at both to collect mapping options, and possibly
throw runtime exceptions.
Sanne
On 26 March 2014 04:13, Steve Ebersole <steve(a)hibernate.org> wrote:
>From the test
org.hibernate.test.annotations.access.jpa.AccessMappingTest#testExplicitPropertyAccessAnnotationsWithHibernateStyleOverride
we have the following:
@Entity
@Access(AccessType.PROPERTY)
public class Course3 {
private long id;
...
@Id
@GeneratedValue
@Access(AccessType.FIELD)
public long getId() {
return id;
}
...
}
The test asserts that this is a valid mapping. Granted that the spec is
very unclear here, so I might be missing something. The pertinent spec
section here states:
*<quote>When Access(PROPERTY) is applied to an entity class, mapped
superclass, or embeddableclass, mapping annotations may be placed on the
properties of that class, and the persistenceprovider runtime accesses
persistent state via the properties defined by that class. All proper-ties
that are not annotated with the Transient annotation are persistent.
WhenAccess(PROPERTY) is applied to such a class, it is possible to
selectively designate indi-vidual attributes within the class for instance
variable access. To specify a persistent instancevariable for access by the
persistence provider runtime, that instance variable must be desig-nated
Access(FIELD).</quote>*
I can see a few different ways to read that:
1) @Access can be placed on the attribute to define both where to look for
mapping annotations and the runtime access strategy for a given attribute.
Here, we'd do:
@Entity
@Access(AccessType.PROPERTY)
public class Course3 {
@Id
@GeneratedValue
@Access(AccessType.FIELD)
private long id;
...
public long getId() {
return id;
}
...
}
2) @Access can be placed on the attribute to define the runtime access
strategy for a given attribute, but the class/hierarchy AccessType controls
where to look for mapping annotations. This would lead to:
@Entity
@Access(AccessType.PROPERTY)
public class Course3 {
@Access(AccessType.FIELD)
private long id;
...
@Id
@GeneratedValue
public long getId() {
return id;
}
...
}
The test seems to illustrate that our legacy code made yet a 3rd reading of
this passage such that @Access is still considered a "mapping annotation"
even though that seems to directly contradict "To specify a persistent
instance
variable for access by the persistence provider runtime, that instance
variable must be desig-
nated Access(FIELD)."
Is there some other passage I am missing that bears on what to do here?
How do y'all feel about that passage and its implications on this test
mapping?
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