Thanks very much for the reply Patrick.
So maybe in term of efficiency, for entities with single primary key, I
should NOT compare entities but the key ("WHERE e.fooType.id = :fooTypeId
"), I'm not sure about composite key?
-Frank
Patrick Linskey-2 wrote:
>
> Hi,
>
> Yes, they must be managed instances. When using a persistent type in a
> query, you are either doing object equality (in which case we must
> have a managed instance to understand how to handle object identity)
> or you are accessing persistent fields (in which case we must be
> hooked into the object in order to dig into it).
>
> IIRC, this behavior is not defined in the spec -- I think the spec
> does not permit queries that directly compare entities.
>
> -Patrick
>
> On 9/17/07, frankca <[EMAIL PROTECTED]> wrote:
>>
>> Hi,
>>
>> I have simple query with Foo and FooType are persistent classes and name
>> is
>> string type:
>> (1) @NamedQuery(
>> (2) name = "Foo.findByTypeAndName",
>> (3) query = "SELECT e " +
>> (4) "FROM Foo e " +
>> (5) "WHERE e.fooType = :fooType " +
>> (6) "AND e.name = :name"
>> (7) )
>>
>> Case 1: if the given fooType is detached then if I create a named query
>> and
>> invoke getSingleResult() returns null.
>> Case 2: if I change the named query line (5) as following and the given
>> fooType is detached then it works:
>> (5) "WHERE e.fooType.id = :fooTypeId " +
>> Case 3: if I "attach" the fooType prior to pass it to the query then it
>> works.
>>
>> Q1: Can someone please confirm is it true that any persistent entities
>> pass
>> as parameters to JPQL queries MUST be attached?
>>
>> Q2: What is the best way to "attach" a persistent entity without knowing
>> it's detached or not? (I invoke EntityManager.contains() and perform
>> EntityManager.find() is this recommended?)
>>
>> TIA,
>> Frank
>>
>> --
>> View this message in context:
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>> Sent from the OpenJPA Users mailing list archive at Nabble.com.
>>
>>
>
>
> --
> Patrick Linskey
> 202 669 5907
>
>
--
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