I just announced the new Spring Boot 2 material, coming in REST With Spring:
Spring Data provides many ways to define a query that we can execute. One of these is the @Query annotation.
In this tutorial, we’ll demonstrate how to use the @Query annotation in Spring Data JPA to execute both JPQL and native SQL queries.
2. Select Query
In order to define SQL to execute for a Spring Data repository method, we can annotate the method with the @Query annotation — its value attribute contains the JPQL or SQL to execute.
The @Query annotation takes precedence over named queries, which are annotated with @NamedQuery or defined in an orm.xml file.
It’s a good approach to place a query definition just above the method inside the repository rather than inside our domain model as named queries. The repository is responsible for persistence, so it’s a better place to store these definitions.
By default the query definition uses JPQL.
Let’s look at a simple repository method that returns active User entities from the database:
@Query("SELECT u FROM User u WHERE u.status = 1") Collection<User> findAllActiveUsers();
We can use also native SQL to define our query. All we have to do is to set the value of the nativeQuery attribute to true and define the native SQL query in the value attribute of the annotation:
@Query( value = "SELECT * FROM USERS u WHERE u.status = 1", nativeQuery = true) Collection<User> findAllActiveUsersNative();
3. Define Order in a Query
We can pass an additional parameter of type Sort to a Spring Data method declaration that has the @Query annotation. It’ll be translated into the ORDER BY clause that gets passed to the database.
3.1. Sorting for JPA Provided and Derived Methods
For the methods we get out-of-the-box like findAll(Sort) or the ones that are generated by parsing method signatures, we can only use object properties to define our sort:
userRepository.findAll(new Sort(Sort.Direction.ASC, "name"));
Now imagine that we want to sort by the length of a name property:
When we execute the above code we’ll receive an exception:
org.springframework.data.mapping.PropertyReferenceException: No property lENGTH(name) found for type User!
When we use JPQL for a query definition, then Spring Data can handle sorting without any problem — all we have to do is to add a method parameter of type Sort:
@Query(value = "SELECT u FROM User u") List<User> findAllUsers(Sort sort);
We can call this method and pass a Sort parameter, which will order the result by the name property of the User object:
And because we used @Query annotation, we can use the same method to get the sorted list of Users by the length of their names:
It’s crucial that we use JpaSort.unsafe() to create a Sort object instance.
When we use:
then we’ll receive exactly the same exception as we saw above for the findAll() method.
When Spring Data discovers the unsafe Sort order for a method that uses the @Query annotation, then it just appends the sort clause to the query — it skips checking whether the property to sort by belongs to the domain model.
When the @Query annotation uses native SQL, then it’s not possible to define a Sort.
If we do, we’ll receive an exception:
org.springframework.data.jpa.repository.query.InvalidJpaQueryMethodException: Cannot use native queries with dynamic sorting and/or pagination
As the exception says, the sort isn’t supported for native queries. The error message gives us a hint that pagination will cause an exception too.
However, there is a workaround that enables pagination, and we’ll cover in the next section.
Pagination allows us to return just a subset of a whole result in a Page. This is useful, for example, when navigating through several pages of data on a web page.
Another advantage of pagination is that the amount of data sent from server to client is minimized. By sending smaller pieces of data, we can generally see an improvement in performance.
Using pagination in the JPQL query definition is straightforward:
@Query(value = "SELECT u FROM User u ORDER BY id") Page<User> findAllUsersWithPagination(Pageable pageable);
We can pass a PageRequest parameter to get a page of data. Pagination is also supported for native queries but requires a little bit of additional work.
We can enable pagination for native queries by declaring an additional attribute countQuery — this defines the SQL to execute to count the number of rows in the whole result:
@Query( value = "SELECT * FROM Users ORDER BY id", countQuery = "SELECT count(*) FROM Users", nativeQuery = true) Page<User> findAllUsersWithPagination(Pageable pageable);
4.3. Spring Data JPA Versions Prior to 2.0.4
The above solution for native queries works fine for Spring Data JPA version 2.0.4 and later.
Prior to that version, when we try to execute such a query we’ll receive an exception — the same one we described in the previous section on sorting.
We can overcome this by adding an additional parameter for pagination inside our query:
@Query( value = "SELECT * FROM Users ORDER BY id \n-- #pageable\n", countQuery = "SELECT count(*) FROM Users", nativeQuery = true) Page<User> findAllUsersWithPagination(Pageable pageable);
In the above example, we add “\n– #pageable\n” as the placeholder for the pagination parameter. This tells Spring Data JPA how to parse the query and inject the pageable parameter. This solution works for the H2 database.
We’ve covered how to create simple select queries via JPQL and native SQL. Next, we’ll show how to define additional parameters.
5. Indexed Query Parameters
There are two possible ways that we can pass method parameters to our query. In this section, we’ll cover indexed parameters.
For indexed parameters in JPQL, Spring Data will pass method parameters to the query in the same order they appear in the method declaration:
@Query("SELECT u FROM User u WHERE u.status = ?1") User findUserByStatus(Integer status); @Query("SELECT u FROM User u WHERE u.status = ?1 and u.name = ?2") User findUserByStatusAndName(Integer status, String name);
For the above queries, the status method parameter will be assigned to the query parameter with index 1, and the name method parameter will be assigned to the query parameter with index 2.
Indexed parameters for the native queries work exactly in the same way as for JPQL:
@Query( value = "SELECT * FROM Users u WHERE u.status = ?1", nativeQuery = true) User findUserByStatusNative(Integer status);
In the next section, we’ll show a different approach — passing parameters via name.
6. Named Parameters
We can also pass method parameters to the query using named parameters. We define these using the @Param annotation inside our repository method declaration.
Each parameter annotated with @Param must have a value string matching the corresponding JPQL or SQL query parameter name. A query with named parameters is easier to read and is less error-prone in case the query needs to be refactored.
As mentioned above, we use the @Param annotation in the method declaration to match parameters defined by name in JPQL with parameters from the method declaration:
@Query("SELECT u FROM User u WHERE u.status = :status and u.name = :name") User findUserByStatusAndNameNamedParams( @Param("status") Integer status, @Param("name") String name);
Note that in the above example, we defined our SQL query and method parameters to have the same names, but it’s not required, as long as the value strings are the same:
@Query("SELECT u FROM User u WHERE u.status = :status and u.name = :name") User findUserByUserStatusAndUserName(@Param("status") Integer userStatus, @Param("name") String userName);
For the native query definition, there is no difference how we pass a parameter via the name to the query in comparison to JPQL — we use the @Param annotation:
@Query(value = "SELECT * FROM Users u WHERE u.status = :status and u.name = :name", nativeQuery = true) User findUserByStatusAndNameNamedParamsNative( @Param("status") Integer status, @Param("name") String name);
Next, we’ll show how to modify data with the @Modifying annotation.
7. Update Queries with @Modifying
We can use the @Query annotation to modify the state of the database by also adding the @Modifying annotation to the repository method.
The repository method that modifies the data has two difference in comparison to the select query — it has the @Modifying annotation and, of course, the JPQL query uses update instead of select:
@Modifying @Query("update User u set u.status = :status where u.name = :name") int updateUserSetStatusForName(@Param("status") Integer status, @Param("name") String name);
The return value defines how many rows the execution of the query updated. Both indexed and named parameters can be used inside update queries.
We can modify the state of the database also with the native query — we just need to add the @Modifying annotation:
@Modifying @Query(value = "update Users u set u.status = ? where u.name = ?", nativeQuery = true) int updateUserSetStatusForNameNative(Integer status, String name);
In this article, we covered several ways of defining queries in Spring Data JPA repository methods using the @Query annotation.
As always, the complete code examples used in this tutorial are available over on Github.