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From Nick Johnson <apa...@spatula.net>
Subject Re: error with multiple joins
Date Mon, 12 Nov 2007 06:46:36 GMT
Found the trouble... if you JOIN, you have to alias:

	JOIN foo.bar bar JOIN bar.baz baz

Also, the trouble with the lazy loading was that I'd closed the 
EntityManager before trying to get at a lazy-loaded field, so naturally 
that wasn't gonna work...


On Sun, 11 Nov 2007, Nick Johnson wrote:

> First, are multiple JOIN clauses supported?  (Sanity check)
> 
> I have a set of classes, BinaryResourceReference, BinaryResourceLocale and 
> BinaryResourceContent.  One BinaryResourceReference may have many 
> BinaryResourceLocales, and each BinaryResourceLocale has one 
> BinaryResourceContent.
> 
> I find that if I do a JPA query for BinaryResourceReference and JOIN FETCH 
> its BinaryResourceLocales, then the content field of each 
> BinaryResourceLocale is null and won't be lazy-loaded.
> 
> If I take another approach and try to join all the way through, with this 
> query:
> 
>     SELECT ref FROM BinaryResourceReference ref JOIN ref.locales locales 
> 	JOIN locales.content WHERE ref.scope = ?1 AND ref.path = ?2 AND 
> 		ref.extension = ?3
> 
> then I get this exception:
> 
> Caused by: <openjpa-1.0.0-r420667:568756 nonfatal user error> 
> org.apache.openjpa.persistence.ArgumentException: Encountered "JOIN 
> locales . content WHERE" at character 70, but expected: [".", "ABS", 
> "ALL", "AND", "ANY", "AS", "ASC", "AVG", "BETWEEN", "BOTH", "BY", 
> "CONCAT", "COUNT", "CURRENT_DATE", "CURRENT_TIME", "CURRENT_TIMESTAMP", 
> "DELETE", "DESC", "DISTINCT", "EMPTY", "ESCAPE", "EXISTS", "FETCH", 
> "FROM", "GROUP", "HAVING", "IN", "INNER", "IS", "JOIN",
> 
> [snip]
> 
> Presumably this is happening either because multiple joins aren't allowed, 
> or I'm doing them the wrong way for this case.  I suspect it's the latter, 
> because the parser claims to have been expecting JOIN.
> 
> I've double-checked the field names just to be sure.  
> BinaryResourceReference#locales is a 1:M to 
> BinaryResourceReferenceLocales, and BinaryResourceReferenceLocales#content 
> is a 1:1 to BinaryResourceContent.
> 
> Any thoughts or suggestions?
> 
>    Nick
> 
> 

-- 
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 afraid and doing what you have to do anyway."
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