Re: [hibernate-dev] Another @Access quandry

I do of course agree that people should use a single strategy and stick to it, so I agree with your reading about what the "general expectation" is. But the original test represents a quite naturally looking example and it's hard to justify why that should be considered illegal; I'd probably be more inclined in making user's life easier than try to lecture them about how a proper mapping should look like. Ignoring any annotation leads to waste of time and debugging frustration, so rather than silently discarding a mis-positioned annotation I'd prefer a fail-fast approach; that said I think just applying them all - as long as there are no obvious conflicting annotations - would be even more user friendly and doesn't seem to violate any specific wording of the spec. Sanne On 26 March 2014 13:57, Steve Ebersole <steve(a)hibernate.org&gt; wrote: > Again from the spec (still discussing class-level Access(PROPERTY)) : "The > behavior is undefined if mapping annotations are placed on any instance > variables defined by the class for which Access(FIELD) is not specified". > > Which to me implies that the expectation for switching access for a > particular field within such a class is to annotate the *field* with > Access(FIELD). > > Also the footnote to this sections seems very relevant: > > "[8] ... It is not permitted to specify a field as Access(PROPERTY) or a > property as Access(FIELD)..." > > > > On Wed, Mar 26, 2014 at 8:02 AM, Emmanuel Bernard < emmanuel(a)hibernate.org&gt; > wrote: >> >> My reading at the time and what I did find more intuitive is what the >> test represents. >> >> Entity level @AccessType expresses where the annotations should >> be. Otherwise the position of @Id is used to find the access type to >> consider annotation wise. >> >> If for a few attributes I wish to use the alternative property access, I >> can add @AccessType next to the other annotations but expressing that >> the actual property value access is based on the alternative access. >> That way, all annotations are in the same place. >> >> On Wed 2014-03-26 11:12, Sanne Grinovero wrote: >> > 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&gt; 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? >> > > _______________________________________________ >> > > hibernate-dev mailing list >> > > hibernate-dev(a)lists.jboss.org >> > > https://lists.jboss.org/mailman/listinfo/hibernate-dev >> > _______________________________________________ >> > hibernate-dev mailing list >> > hibernate-dev(a)lists.jboss.org >> > https://lists.jboss.org/mailman/listinfo/hibernate-dev > >