QueryDSL Web Support

For those stores that have QueryDSL integration, you can derive queries from the attributes contained in a Request query string.

Consider the following query string:

?firstname=Dave&lastname=Matthews

Given the User object from the previous examples, you can resolve a query string to the following value by using the QuerydslPredicateArgumentResolver, as follows:

QUser.user.firstname.eq(“Dave”).and(QUser.user.lastname.eq(“Matthews”))

The feature is automatically enabled, along with @EnableSpringDataWebSupport, when Querydsl is found on the classpath.

Adding a @QuerydslPredicate to the method signature provides a ready-to-use Predicate, which you can run by using the QuerydslPredicateExecutor.

Type information is typically resolved from the method’s return type. Since that information does not necessarily match the domain type, it might be a good idea to use the root attribute of QuerydslPredicate.

The following example shows how to use @QuerydslPredicate in a method signature:

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@Controller class UserController { @Autowired UserRepository repository; @RequestMapping(value = "/", method = RequestMethod.GET) String index(Model model, @QuerydslPredicate(root = User.class) Predicate predicate, Pageable pageable, @RequestParam MultiValueMap parameters) { model.addAttribute("users", repository.findAll(predicate, pageable)); return "index"; } }

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The default binding is as follows:

Object on simple properties as eq.

Object on collection like properties as contains.

Collection on simple properties as in.

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You can customize those bindings through the bindings attribute of @QuerydslPredicate or by making use of Java 8 default methods and adding the QuerydslBinderCustomizer method to the repository interface, as follows:

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interface UserRepository extends CrudRepository, QuerydslPredicateExecutor, QuerydslBinderCustomizer { @Override default void customize(QuerydslBindings bindings, QUser user) { bindings.bind(user.username).first((path, value) -> path.contains(value)) bindings.bind(String.class) .first((StringPath path, String value) -> path.containsIgnoreCase(value)); bindings.excluding(user.password); } } QuerydslPredicateExecutor provides access to specific finder methods for Predicate. QuerydslBinderCustomizer defined on the repository interface is automatically picked up and shortcuts @QuerydslPredicate(bindings=…​). Define the binding for the username property to be a simple contains binding. Define the default binding for String properties to be a case-insensitive contains match. Exclude the password property from Predicate resolution.

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