I'd like to create query like this with QueryDSL
update WorkMessage w set w.totalPrice = 0.12 - w.totalCost;
I tried like this
Expression<Float> priceExpr = Expressions.constant(0.12f);
new JPAUpdateClause(em, w)
.set(w.totalPrice , priceExpr.subtract(w.totalCost));
But this doesn't work - Expression doesn't have subtract method.
I did it like this:
new JPAUpdateClause(em, w)
.set(w.totalPrice , w.totalCost.subtract(0.12f).negate());
but I'd like to know how to do it the first way.
//EDit
The second way don't work:
JPAUpdateClause.toString says:
update WorkMessage workMessage
set workMessage.totalPrice = -(workMessage.totalCost - :a1)
but the SQL result is
update work_message set total_price=-total_cost-?
Parentheses just dissapeared. Am I doing something wrong? It looks like theese:
w.totalCost.subtract(0.12f).negate()
w.totalCost.negate().subtract(0.12f)
have the same result.
For the above problem
w.totalCost.negate().add(0.12f)
works. But I think there is a bug.
2 Answers
We removed the DSL Constant types some time ago from Querydsl. If you really want to write it the first way, then you have to express it like this :
Expressions.operation(Float.class, Ops.SUB,
Expressions.constant(0.12f), w.totalCost)
or
NumberOperation.create(Float.class, Ops.SUB,
Expressions.constant(0.12f), w.totalCost)
if you need a NumberExpression
I had the same problem some time ago (needed the constant 0), and did build my own ConstantNumberExpression class. It turned out surprisingly easy :-)
A collegue just had the same problem, for the constant 1, so I decided to post it here.
private static class ConstantNumberExpression extends NumberExpression<Integer> {
private static final long serialVersionUID = 1220768215234001828L;
public ConstantNumberExpression(final int constant) {
super(new ConstantImpl<>(constant));
}
@Override
@Nullable
public <R, C> R accept(final Visitor<R, C> v, @Nullable final C context) {
return v.visit((Constant<Integer>) mixin, context);
}
}
Of course this could be done a bit more generic, using a type parameter, but we did need it only for Integer (actually only for zero and one).
