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The previous part of this tutorial described how we can create database queries with the Query annotation. This tutorial has now covered two of the three methods which we can use to create query methods with Spring Data JPA.
This blog post describes the last method. We will learn to create database queries by using named queries. If you are not familiar with Spring Data JPA, you should read the following blog posts before you continue reading this blog post:. Before we can implement our search function, we have to understand how we can use named queries with Spring Data JPA. In other words, we have to find the answers to these questions:. We can specify named queries with Spring Data JPA by using a properties file, annotations, or the orm.
Before can take a closer look at these methods, we have to learn a few rules that we must follow when we are specifying the names of our named queries.
These rules are:. We can declare named queries by adding them into the jpa-named-queries. If you want to get more information about this, check out the following webpages:. We can declare named queries by adding them into the orm. We have to use one of these two XML elements:. We want to create a query method that invokes the named query whose name is: Todo.
If the invoked named query is a JPQL query, we have to add the following query method into our repository interface:. If the invoked named query is a SQL query, we have to add the following query method into our repository interface:.
We want to create the query method which invokes the named query whose name is: Todo. This named query has one named parameter called description.
If the invoked query is a JPQL query, we have to add the following query method into our repository interface:.Serializable; import javax. Column; import javax. Entity; import javax. GeneratedValue; import javax. GenerationType; import javax. Id; import javax. Driver spring.
MySQLDialect spring. List; import com. List; import javax. EntityManager; import javax. PersistenceContext; import org. Repository; import org. Transactional; import com. List; import org. Autowired; import org. Service; import com. IArticleDAO; import com.
Spring Boot Data JPA @Query tutorial
HttpHeaders; import org. HttpStatus; import org. ResponseEntity; import org. Controller; import org. DeleteMapping; import org. GetMapping; import org.
PathVariable; import org. PostMapping; import org. PutMapping; import org. RequestBody; import org. RequestMapping; import org.
UriComponentsBuilder; import com. Article; import com. SpringApplication; import org. URI; import org.Comment 1. Because of this, I decided to create the "Spring Native Query" library to facilitate the execution of native queries, with a focus on simplifying the source code, making it more readable and clean, creating files that contain the native queries, and dynamically injecting assets to execute those queries.
In the end, we register the beans of those interfaces dynamically, so we can inject the interfaces into all the components of the Spring. The convention works as follows. The method name is the name of the file that contains the SQL query; the parameters of the methods will then be passed as parameters to the entity manager. The method return is the object that will be transformed with the result returned from the query.
The file that contains the SQL query is a Jtwig template where we can apply validations modifying the whole query, adding filters, changing links between tables, and finally any changes in SQL. Remember, the file name must be the same as the method name. Here are some examples for a better understanding. When starting the project, let's create a SQL script by creating a new table and inserting some records. All sample source code is in GitHub.
For each method of the interface created above, we have to create a file containing the queries. If you have multiple interfaces and want to split the files of the queries into folders, just add the following annotation on top of the interface informing which files folder. For the future of the library, we have some improvements, such as allowing the user to change the folder where the queries are found, as well as the extension of the files, for example.
Over a million developers have joined DZone. Let's be friends:. DZone 's Guide to. What is the Spring Native Query Library? And how do you run native queries with it? Free Resource. Like Join the DZone community and get the full member experience. Join For Free. In your project, add the dependency of the library. Let's take an example using Maven. NativeQueryOperator; import io. NativeQueryParam; import lombok. NativeQuery; import io.
NativeQueryParam; import org. Page; import org. Pageable; import java. Autowired; import org. PageRequest; import org. So, stay tuned! Like This Article?Are you tired of writing tests which have a lot of boilerplate code?
This blog entry will describe how you can use query methods for creating custom queries with Spring Data JPA. In order to have a reasonable example, I have created three new requirements for my example application:. Spring Data JPA provides three different approaches for creating custom queries with query methods.
Each of these approaches is described in following. Spring Data JPA has a built in query creation mechanism which can be used for parsing queries straight from the method name of a query method. This mechanism first removes common prefixes from the method name and parses the constraints of the query from the rest of the method name.
Using this approach is quite simple. All you have to do is to ensure that the method names of your repository interface are created by combining the property names of an entity object and the supported keywords. The strength of this approach is that it is rather fast to implement simple queries. On the other hand, if your query has many parameters, your method name will be rather long and ugly.
A good example of this is the fact that at the moment you cannot use the lower keyword in your method names. This means that this approach cannot be used to fulfill the requirements which I specified in the beginning.
You have got following alternatives for declaring the named queries:. The only thing you have to do to use the created named queries is to name the query method of your repository interface to match with the name of your named query. I have chosen to specify the named query by using NamedQuery annotation in my entity class.
Using named queries is valid option if your application is small or if you have to use native queries. If your application has a lot of custom queries, this approach will litter the code of your entity class with query declarations You can of course use the XML configuration to avoid this but in my opinion this approach is even more horrible.
The Query annotation can be used to create queries by using the JPA query language and to bind these queries directly to the methods of your repository interface. When the query method is called, Spring Data JPA will execute the query specified by the Query annotation If there is a collision between the Query annotation and the named queries, the query specified by using Query annotation will be executed.
The source code of the repository method which is implemented by using this approach is given in following:. This approach gives you access to the JPA query language and keeps your queries in the repository layer where they belong. On the other hand, you cannot use the Query annotation I will describe more advanced strategies in the next parts of this tutorial if the JPA query language cannot be used to create the query you need.
The next step is to take a look of the service class which uses the created query methods. The SearchType enumeration identifies the used query method. Its source code is given in following:.
The PersonService interface has got one new method. The relevant part of the PersonService interface is described in following:. The actual implementation of the search method is responsible of selecting the correct query method and passing the given search term to it. The source code of my search method implementation is given in following:. Naturally the created search must be tested as well. The source code of the relevant unit tests is given in following:.
I have now described to you how you can use query methods for creating custom queries with Spring Data JPA. If you are interested of seeing my example application in action, you can get it from Github. Excellent tutorials.Here is an example of Users Repository interface which has a query method with Query annotation:.
Spring Data JPA @Query Annotation Example
But what if we need to pass the value as a method parameter? Below is an example if the same Spring Data JPA Native query which selects all users with email verification status set to true but the value of email verification status is passed as an Indexed Query Parameter:.
We can also pass more than one Index Query Parameter. The below code snippet demonstrates how to use indexed query parameters with JPQL:. There is one more way to pass parameters to a native query and it is to use Named Parameters. To pass a parameter to a native query we will need to use Param annotation and make sure that the name used in the Param annotation matches the variable name used in the native query. Have a look at the example below:.
Additionally, to selecting records from a database table you can use Query annotation to perform an update SQL query. If you are interested in learning more about Spring Data JPA, please have a look at the list of video courses below or search this website by a keyword: JPA. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. Leave a Reply Cancel reply Your email address will not be published. Video Tutorials.Spring is a popular Java application framework for creating enterprise applications.
Spring Boot is an evolution of Spring framework which helps create stand-alone, production-grade Spring based applications with minimal effort.
Spring Data JPA Custom Queries using @Query Annotation
It enhances support for JPA based data access layers. It makes it easier to build Spring-powered applications that use data access technologies. The Query annotation declares finder queries directly on repository methods. This frees the domain classes from persistence specific information, which is a good thing.
In the application. The server. With the spring. The spring. It is used in the initialization scripts. Finally, the spring. This is the City entity. Each entity must have at least two annotations defined: Entity and Id.
The Entity annotation specifies that the class is an entity and is mapped to a database table. The Table annotation specifies the name of the database table to be used for mapping. The Id annotation specifies the primary key of an entity and the GeneratedValue provides for the specification of generation strategies for the values of primary keys.
When the application is started, the schema-h2. It creates a new database table. By extending from the Spring CrudRepositorywe will have some methods for our data repository implemented.
In addition, we create a custom findByNameEndsWith method.
It returns cities whose names end in the provided characters. ICityService provides a contract method to get all cities ending in certain characters.
We use the repository to retrieve data from the database. The findByNameEndsWith method of the repository returns the list of cities ending in certain characters. The model gains a list of matching cities and the processing is sent to the showCities.
The Application sets up the Spring Boot application. The SpringBootApplication enables auto-configuration and component scanning. You might also be interested in the related tutorials:.In an earlier articleI explained how to create and use derived query methods to retrieve data from the database in Spring Data JPA. Derived queries are good as long as they are not complex.
As the number of query parameters goes beyond 3 to 4, you need a more flexible strategy. Then add sorting, filtering, comparison, and result size limiting keywords to derived queries, it would have become practically impossible to read and maintain these queries.
The Query annotation defines queries directly on repository methods. This gives you full flexibility to run any query without following the method naming conventions.
Let us extend this application to add another entity and a repository interface. Next, add the following NoteRepository interface to save and fetch notes from the database:. According to Wikipedia :. JPQL is used to make queries against entities stored in a relational database. Clearly, JPQL is just an object-oriented way of defining queries based on entity attributes. The JPA implementation you use, which is Hibernate by default, will then execute the query and return the result.
So, it may not be a great choice for complex queries.
The same query can be written in native SQL format. All you need to do is just set the nativeQuery attribute value to true and define the native SQL query in the value attribute of the Query annotation:. Bind parameters act as a placeholder in a custom query that must be replaced with actual values before the query gets executed. You can either use positional also called indexed or named bind parameters. A positional bind parameter is referenced by its position in the query.
They are defined with? Spring Data JPA will automatically set the bind parameter values. It replaces the value of each method parameter with the value of a bind parameter in the same position.
For example, the first method parameter value becomes the bind parameter value at position 1, the second method parameter value becomes the bind parameter value at position 2, and so on.