Spring Data Extensions

This section documents a set of Spring Data extensions that enable Spring Data usage in a variety of contexts. Currently, most of the integration is targeted towards Spring MVC.

Querydsl Extension

Querydsl is a framework that enables the construction of statically typed SQL-like queries through its fluent API.

Querydsl maintenance has slowed down to a point where the community has forked the project under OpenFeign at github.com/OpenFeign/querydsl (groupId io.github.openfeign.querydsl). Spring Data supports the fork on a best-effort basis.

Several Spring Data modules offer integration with Querydsl through QuerydslPredicateExecutor, as the following example shows:

QuerydslPredicateExecutor interface

public interface QuerydslPredicateExecutor<T> {

  Optional<T> findById(Predicate predicate);  (1)

  Iterable<T> findAll(Predicate predicate);   (2)

  long count(Predicate predicate);            (3)

  boolean exists(Predicate predicate);        (4)

  // … more functionality omitted.
}

1	Finds and returns a single entity matching the `Predicate`.
2	Finds and returns all entities matching the `Predicate`.
3	Returns the number of entities matching the `Predicate`.
4	Returns whether an entity that matches the `Predicate` exists.

To use the Querydsl support, extend QuerydslPredicateExecutor on your repository interface, as the following example shows:

Querydsl integration on repositories

interface UserRepository extends CrudRepository<User, Long>, QuerydslPredicateExecutor<User> {
}