Querydsl: Casebuilder could not determine data type for searched case statement

Created on 13 Jul 2016 · 5Comments · Source: querydsl/querydsl

The old code:

new CaseBuilder() .when(foo.id.eq(NumberTemplate.create(Integer.class, "1").then(BooleanTemplate.FALSE) .when(foo.id.eq(NumberTemplate.create(Integer.class, "2").then(BooleanTemplate.TRUE) .otherwise(new NullExpression<>(Boolean.class)

I've tried replacing it with

new CaseBuilder() .when(foo.id.eq(Expressions.asNumber(1).then(false) .when(foo.id.eq(Expressions.asNumber(2)).then(true) .otherwise(Expressions.nullExpression(Boolean.class))

which didn't work. I get the error

org.hibernate.QueryException: Could not determine data type for searched case statement

I then tried using Expressions.constant(), which also didn't work. Finally, I tried Expressions.asBoolean() and Expressions.FALSE, which doesn't compile due to ambiguous method call: valid in Predicate and ComparableExpression.

I should note that explicitly casting Expressions.FALSE to Expression does allow the code to compile (and generate valid SQL), although now there are unchecked warnings.

hibernate resolved

Source

michaelhum

Most helpful comment

Hibernate doesn't know what type ? is in the query, but needs to know in case expressions.

Using templates like the answer on stackoverflow is an option.
It makes us serialize whatever is in the template as-is.

Other than that, it's a hibernate issue.

Shredder121 on 15 Jul 2016

👍2

All 5 comments

Somehow, the syntax you mentioned is not fitting, could you try this:

new CaseBuilder()
.when(foo.id.eq(Expressions.asNumber(1))).then(false)
.when(foo.id.eq(Expressions.asNumber(2))).then(true)
.otherwise(Expressions.nullExpression(Boolean.class))

See the extra ) after Expressions.asNumber(1)

tan31989 on 14 Jul 2016

My apologies - typo with copying over the code. I still get the same result.

michaelhum on 14 Jul 2016

I guess you can give a try for this solution that was related to Hibernate doing something with lietrals: http://stackoverflow.com/questions/26648491/querydsl-could-not-determine-data-type-for-searched-case-statement#answer-27190771

tan31989 on 15 Jul 2016

👍1

Hibernate doesn't know what type ? is in the query, but needs to know in case expressions.

Using templates like the answer on stackoverflow is an option.
It makes us serialize whatever is in the template as-is.

Other than that, it's a hibernate issue.

Shredder121 on 15 Jul 2016

👍2

Hi,

I'll give it a try - although I've tried numerous templates. Is there a specific one? In 3.x I was using NumberTemplate and BooleanTemplate but in 4 I believe it is now different?

I've tried:

Expressions.asBoolean()
Expressions.constant()
Expressions.FALSE

As I did mention though, this syntax:

.when(Expressions.asNumber(1))
.then(Expressions.asBoolean(false))
.when(Expressions.asNumber(2))
.then(Expressions.asBoolean(true))
.otherwise(Expressions.nullExpression(Boolean.class))

results in a compilation error (ambiguous method call with '.then(Expressions.asBoolean(false))' - both overridden in ComparableExpression and Predicate apply. I can make it work by casting the result to Expression, is this expected behaviour?

michaelhum on 16 Jul 2016

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