Calling Postgres function using QueryDSL

Question

I have a package with similarity functions installed on my Postgres DB. I was calling them using pure SQL on a JDBC, and it was working as expected.

Now I'm trying to refactor my code to use QueryDSL. The first step of the similarity function is set a limit, between 0 and 1, so that only results above that given threshold are returned. I'm trying this way:

NumberExpression<Float> sim = Expressions.numberTemplate(Float.class, "set_limit({0})", "0.2"); query.singleResult(sim);

I get the following error: java.lang.IllegalArgumentException: No joins given

I know I haven't passed an EntityPath. If I try and use any EntityPath, I get the error:

`[[IllegalStateException: No data type for node: org.hibernate.hql.internal.ast.tree.MethodNode
 \-[METHOD_CALL] MethodNode: '('
    +-[METHOD_NAME] IdentNode: 'set_limit' {originalText=set_limit}
    \-[EXPR_LIST] SqlNode: 'exprList'
       \-[NAMED_PARAM] ParameterNode: '?' {name=1, expectedType=null}
]]`

After that, I'd call another DB function, but I guess the solution would be the same.

Is this possible with QueryDSL?

Timo Westkämper · Accepted Answer · 2015-04-27 19:52:52Z

1

set_limit isn't valid JPQL, that's why Hibernate throws an exception. Querydsl JPA maps internally to JPQL, and Querydsl SQL to SQL.

If you need SQL expressivity, like in this case, you will need to use Querydsl SQL instead.

answered Apr 27, 2015 at 19:52

Timo Westkämper

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