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https://issues.apache.org/jira/browse/JDO-630?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12702456#action_12702456
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Craig Russell commented on JDO-630:
-----------------------------------
> All objects returned by the implementation will have exact ids. All ids
> returned by PM.getObjectId() will also be exact.
This seems to be the right direction. But there are a few APIs that we should
revisit. Here's a proposal to change the spec but leave the API exactly as it
is:
Object getObjectById (Object oid, boolean validate);
Add to the description of validate false:
The user asserts that the oid contains the exact id, so if the object is not in
the cache, the implementation constructs a hollow instance of the class in the
oid. If the class is abstract, throw StupidUserException (we cannot construct a
hollow instance of an abstract class). If the class is actually not correct, an
exception with a possibly confusing error message might be thrown later. Caveat
user. Test case needed.
<T> T getObjectById (Class<T> cls, Object key);
This is already described as having identical behavior to pm.getObjectById
(pm.newObjectIdInstance (cls, key), true), so no change.
Object getObjectById (Object oid);
This is already described as having identical behavior to pm.getObjectById(oid,
true), so no change.
Object[] getObjectsById (boolean validate, Object... oids);
This is defined as iterating the oids and calling getObjectById(oid, validate)
so no change.
Collection getObjectsById (Collection oids);
This is already described as having identical behavior to
pm.getObjecstById(true, oids), so no change.
> Support specification of exact class in SingleFieldIdentity
> -----------------------------------------------------------
>
> Key: JDO-630
> URL: https://issues.apache.org/jira/browse/JDO-630
> Project: JDO
> Issue Type: Improvement
> Components: api2
> Reporter: Andy Jefferson
> Fix For: JDO 2 maintenance release 3
>
> Attachments: singlefieldidentity_exact.patch
>
>
> When calling PersistenceManager.getObjectById() with a SingleFieldIdentity,
> there seems to be no way of avoiding the following
> (if the implementation decides to do so):
> "It is an implementation decision whether to access the data store, if
> required to determine the exact class. This will be the case of inheritance,
> where multiple <code>PersistenceCapable</code> classes share the same
> ObjectId class."
> Now when I know for sure that the targetClassName of the given
> SingleFieldIdentity already denotes the correct class for the given id, how
> can I avoid that additional roundtrip to the database for finding the exact
> class?
> It would be useful to have a way of specifying a SingleFieldIdentity to be
> for the exact class specified. This could be done by addition of methods
> void setExact(boolean flag);
> boolean getExact();
> to SingleFieldIdentity
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