Querydsl：字段未在子类上正确初始化

Question

Good day,

We are using qdsl to access our inherited objects. We have a parent class ( Parent ) which has a complicated object ( BasicProduct ) as a field. Then we have several children (one of them is Child ). In the query we are trying to access the BasicProduct from the QChild autogenerated code. From what we have seen - the field to access the BasicProduct exists on both the QParent and QChild but only the one on the QParent is correctly initialised.

The structure of the objects is:

Parent object -

@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(
name="TYPE",
discriminatorType= DiscriminatorType.STRING)
public abstract class Parent

    //bunch of fields

    @OneToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "BASIC_PRODUCT_ID")
    protected BasicProduct basicProduct;
}

Child object -

@DiscriminatorValue(value = "Child")
public class Child extends Parent {
    //bunch of fields
}

The access query:

HibernateQuery query = new HibernateQuery(session);

query = query.distinct().from(thing)
.leftJoin(thing.childSet, child)
.leftJoin(child.basicProduct(), basicProduct)
.leftJoin(child.basicProduct().fieldA, fieldA)
.leftJoin(basicProduct.fieldB, fieldB);

The access query above fails to build. What are we doing wrong?

Answer 1

Looks like you have mixed types of entity accessor generation. Parent seems to have entityAccessors and Child does not. This could lead to issues when the fields in QChild do not get initialized.

Try to set entityAccessors on QChild too.

Answer 2

If you look at your generated QChild , it should contain the fields inherited from its parent (with a ///inherited comment above the field). All inherited fields are public final , so you can use them.

That said, basicProduct is in QChild , and you can access it - remove brackets from your code

instead of

.leftJoin(child.basicProduct(), basicProduct)

you should have

.leftJoin(child.basicProduct, basicProduct)