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JPA: order by length? [message #385414]

Fri, 30 January 2009 11:05

Tom Eugelink

Messages: 817
Registered: July 2009

Senior Member

Is there a way (aside from native queries) to do an order-by-length query?

.... order by length(t.iDescription)

Tom

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Re: JPA: order by length? [message #385423 is a reply to message #385414]

Mon, 02 February 2009 13:39

James Sutherland

Messages: 1939
Registered: July 2009
Location: Ottawa, Canada

Senior Member

I don't think JPQL allows this, but you can do it through EclipseLink's
query API.

ExpressionBuilder builder = new ExpressionBuilder();
ReadAllQuery query = new ReadAllQuery(YourClass.class, builder);
query.setSelectionCriteria(builder.get("iDescription").like( "%something%"));
query.addOrdering(builder.get("iDescription").length());

Query jpaQuery =
((JpaEntityManager)entityManager.getDelegate()).createQuery( query);

Please vote for this bug to get these functions added to JPQL in
EclipseLink:
https://bugs.eclipse.org/bugs/show_bug.cgi?id=219814

---
James
http://www.nabble.com/EclipseLink---Users-f26658.html

James : Wiki : Book : Blog : Twitter

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Re: JPA: order by length? [message #385424 is a reply to message #385423]

Mon, 02 February 2009 15:21

Tom Eugelink

Messages: 817
Registered: July 2009

Senior Member

> Query jpaQuery =
> ((JpaEntityManager)entityManager.getDelegate()).createQuery( query);

Do I need a specific version of EclipseLink? The one I use (1.0.2) does not have a createQuery method that accepts a ReadAllQuery as a parameter.

Tom

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Re: JPA: order by length? [message #385425 is a reply to message #385424]

Mon, 02 February 2009 15:31

Tom Eugelink

Messages: 817
Registered: July 2009

Senior Member

I used a Collections.sort on the result to order by length. That'll do fine.

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Re: JPA: order by length? [message #385430 is a reply to message #385424]

Tue, 03 February 2009 12:54

James Sutherland

Messages: 1939
Registered: July 2009
Location: Ottawa, Canada

Senior Member

Might only be in 1.1, in 1.0 you can use,

Query jpaQuery = entityManager.createQuery("Select a from MyClass a");
((JpaQuery)query).setDatabaseQuery(query);

James : Wiki : Book : Blog : Twitter

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