Missing join when using sub-type in a predicate and InheritanceType.JOINED

[Casey]

Summary:

Given a base `Person` class, and an `Employee subtype` specified with InheritanceType.JOINED, along with a `PersonContainer` that has a relationship to a person, invalid sql is generated given the predicate:

```java

QPersonContainer.personContainer.person.as(QEmployee.class).name.likeIgnoreCase(name)

```

Details:

// Base type

@Entity

@Inheritance(strategy = InheritanceType.JOINED)

@DiscriminatorColumn(discriminatorType = DiscriminatorType.STRING)

class Person {

  @Id

  Long id;

}

// Sub type

@Entity

@DiscriminatorValue("employee")

class Employee extends Person {

 

  @Column

  String name;

}

// The object I'm querying by

@Entity

class PersonContainer {

  @OneToOne

  private Person person;

}

I create a predicate with:

BooleanBuilder bb = new BooleanBuilder();

bb.and(QPersonContainer.personContainer.person.as(QEmployee.class).name.likeIgnoreCase(name))

personContainerRepository.findAll(bb);

The generated SQL looks like this:

SELECT count(personcont0_.id) AS col_0_0_

FROM db.person_container personcont0_

  CROSS JOIN db.person person1_

WHERE personcont0_.person_id = person1_.id

      AND (lower(person1_1_.name) LIKE '%mary%')

This fails with the root cause:

org.postgresql.util.PSQLException: ERROR: missing FROM-clause entry for table \"person1_1_\"\

You can see in the generated sql the error: person1_1_ is referenced but is not defined in a join anywhere. The query would work fine if this line was added after the cross join:

INNER JOIN db.employee as person1_1_ on person1_1_.id = person1_.id

Since I'm using a spring-data repository I don't have access to the JPQLQuery and can't specify the join myself. But anyways, it should be automatically created no?

Am I generated the predicate incorrectly? Or is this a bug?

(as I suspect this is a bug, I also cross-posted to https://github.com/querydsl/querydsl/issues/2055)

Cheers,

Casey