How to build a dynamic query in JPA?

Question

Java

Hello.
There is a helloworld project on Spring + Hibernate.
There are three entities: Offer, Car and Brand. Described in hbm.xml.
They are related as follows: Offer.car and Car.brand.
I need to get all Offers by Brand.id.
In SQL it looks like this: select * from offers, cars, brands where offers..car_id = cars.id and cars.brand_id = brands.id and brands.id = n;
I want to file a dynamic query build if only the entities at the ends of the chain are known. For example, when in the chain E1.e2 -> E2.e3 -> . . . -> En.em -> Em only E1 and Em are known, and the length of the chain of related entities is not known. Hence the question: is there any ready-made elegant way to get a list of entities? Or maybe you can immediately get the ResultSet?
You need to avoid things like:
1. SQL hardcoding via the @Query annotation.
2. use of string constants with table names.
3. filing a separate findAll () method in the service for each request.
I use JpaSpecificationExecutor.findAll(Specification)) and classes that extend CrudRepository, JpaSpecificationExecutor.

Answer 1

criteria API.

Answer 2

As a variant of querydsl