Java – querydsl – case expression with string value

QueryDsl 3.3. four

public class Document {
    private Confirmation confirmation;
}

public class Confirmation {
    ...
}

I need this query:

SELECT count(d.id),CASE WHEN d.confirmation_id IS NULL then 'NOT_CONFIRMED' else 'CONFIRMED' END as confirmed FROM document d GROUP BY confirmed;

So it should be grouped according to the result of the case expression above Now, translate the case part into querydsl:

StringExpression confirmExp = new CaseBuilder()
    .when(Expressions.booleanTemplate("confirmation_id is null"))
    .then(Expressions.stringTemplate("NOT_CONFIRMED"))
    .otherwise(Expressions.stringTemplate("CONFIRMED"));

I'm using it When (expressions. Boolean template ("confirmation_id is null")) to avoid joining the confirmation table Running a query using such an expression, I get an exception below Is this another hibernate error or does this need to be different?

Solution

If you want to use string text in your query, you need to write it as

StringExpression confirmExp = new CaseBuilder()
    .when(Expressions.booleanTemplate("confirmation_id is null"))
    .then(Expressions.stringTemplate("'NOT_CONFIRMED'"))
    .otherwise(Expressions.stringTemplate("'CONFIRMED'"));

Expressions. Stringtemplate does not mean that the parameter is serialized as string literal, but the type of expression created is Java lang.String.