How to build a condition based on a composite data type with jOOQ?

Question

In my view I have a column that refers to another table as its data type:

CREATE VIEW my_view AS
SELECT c.*, CAST(p.* AS parent) AS entity_parent
FROM entity_child c
LEFT JOIN parent p ON c.parent_id = p.id
GROUP BY c.id, p.id;

I need to query the view based on a value of the entity/parent value. With PostgreSQL it looks like:

SELECT *
FROM my_view
WHERE (entity_parent).secret_value = 42;

jOOQ nows the correct data type of entity_parent (ParentRecord), but I failed to translate my query.

Has anyone an idea?

Answer 1

The jOOQ API currently doesn't allow for generating UDT element dereferencing expressions out of the box. The relevant feature request is this: https://github.com/jOOQ/jOOQ/issues/228

However, as always, you can easily work around such a limitation in the jOOQ API by using the plain SQL templating API: https://www.jooq.org/doc/latest/manual/sql-building/plain-sql-templating

public static <T, U extends UDTRecord> Field<T> dereference(
    Field<? extends U> parent, 
    UDTField<U, T> child
) {
    return DSL.field("({0}).{1}", child.getDataType(), parent, child.getUnqualifiedName());
}

And then, use it as follows:

ctx.selectFrom(MY_VIEW)
   .where(dereference(MY_VIEW.ENTITY_PARENT, Parent.SECRET_VALUE).eq(42))
   .fetch();