Re: what to expect - jpa spec or impl discretion

[Craig L Russell]

The spec says in 3.6.1 "TheelementsoftheresultofaJavaPersistencequerywhoseSELECTclauseconsistsofmorethanone selectexpressionareoftypeObject[]" with apologies to those who prefer spaces in sentences.

Craig

On Jul 21, 2008, at 10:45 AM, Pinaki Poddar wrote:

So the result of a SELECT MIN(e.sequence), MAX(e.sequence) should be an Object[] in which the first element is the MIN and the second element the MAX. If you use getResultList, then the result will be a List each element of which is an Object[2]. If you call getSingleResult, the result will be a single Object[2].

Hi,

I'm a little confused by your example.  You indicate that OpenJPA is

single Object?

returning an array of Objects? Did you mean that OpenJPA is returning a

and @SQLResultSetMapping.
 For example, a SQL
    SELECT p.name, p.age FROM PERSON p WHERE p.age > 20

 may select 42 rows. In that case, OpenJPA will return a List of 42

being p.name and 1-st element is p.age.




Beyer,Nathan wrote:

For results of native queries, OpenJPA returns a List. But each member of the list can be Object[] depending upon what has been selected by the query elements where each element is a Object[] of length 2 with 0-th element

Re: the question about the return type of the native query

To clarify, this is what I see in OpenJPA ...


final Query query = entityManager.createNativeQuery("SELECT
MIN(e.sequence), MAX(e.sequence) FROM LOG e");


is an Object[], so to process, you do this.
final List result = query.getResultList();
final Object[] e0 = (Object[])result.get(0);
final Number minSeq = (Number)e0[0];
final Number maxSeq = (Number)e0[1];



process, you do this.
final Object result = query.getSingleResult();
final Object[] e0 = (Object[])result;
final Number minSeq = (Number)e0[0];
final Number maxSeq = (Number)e0[1];



-----Original Message-----
From: Kevin Sutter [mailto:[EMAIL PROTECTED]
Sent: Monday, July 21, 2008 12:01 PM
To: users@openjpa.apache.org
Subject: Re: what to expect - jpa spec or impl discretion

Nathan,

a

EclipseLink forum might be interesting as well...

// LOG is table name with a 'sequence' column/field of Java type 'long' If you use 'getResultList', then a List is return with one element, which If you use 'getSingleResult', then just the Object[] is returned, so to Comments embedded below. This is just my interpretation of the spec (I am member of the JPA expert group, but I am not the lead). Posting to the On Mon, Jul 21, 2008 at 10:15 AM, Beyer,Nathan <[EMAIL PROTECTED]> wrote:

I'm trying to write a bit of code that's portable between JPA providers

and

bits
of the spec or just me doing something silly.


long

Is
this in the spec or up for debate?

ran into a few differences and I'd like to know if they are undefined 1. 0 is considered null for primary key fields (@Id) of type int, - OpenJPA DOES NOT do this, but other providers, such as EclipseLink do.

type.  But, logic would say that 0 is a valid int or long and, thus,
should

in my book.

The spec does not identify valid values for a given annotation or field be allowed as a primary key value. Of course, you could say that this wouldn't be a very solid value for a primary key, but it should be allowed

2.      Return value of native queries is an Object[] or a List -
Consider
the following snippets


Java
type 'long'
      final Query query = entityManager.createNativeQuery("SELECT
MIN(e.sequence), MAX(e.sequence) FROM LOG e");
      final Object result = query.getSingleResult();


is returned. Is this defined anywhere? How can I define it.

// LOG is table name with a 'sequence' column/field of With OpenJPA a Object[] is returned, in EclipseLink a List

I'm a little confused by your example.  You indicate that OpenJPA is

single Object?  The JavaDoc for getSingleResult is like this:

/**
* Execute a SELECT query that returns a single result.
* @return the result
* @throws NoResultException if there is no result
* @throws NonUniqueResultException if more than one result
* @throws IllegalStateException if called for a Java
* Persistence query language UPDATE or DELETE statement
*/
public Object getSingleResult();


but returning an array of Objects seems like a stretch.


If I wanted to process a List, then I would call getResultList.  The
example
usage in the spec also supports this interpretation.

Good luck with your comparisons,
Kevin

returning an array of Objects? Did you mean that OpenJPA is returning a So, I could see where someone might return a List (since it's an Object), Given that, I would expect the result to be a single Object (not a List).

Thanks,
-Nathan

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Craig L Russell
Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
408 276-5638 mailto:[EMAIL PROTECTED]
P.S. A good JDO? O, Gasp!

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