Spring Data REST and QueryDSL HTTP Query Parameter: Tech Support Site
Spring Data REST is a powerful framework that simplifies the development of RESTful services for Spring-based applications. One of the key features of Spring Data REST is its support for QueryDSL, a popular framework for building type-safe queries in Java. QueryDSL allows developers to construct complex queries using a fluent interface, which can then be translated into various query languages, including SQL, JPQL, and MongoDB query language.
QueryDSL HTTP Query Parameter
Spring Data REST supports QueryDSL HTTP query parameter, which allows clients to specify query criteria using a simple and intuitive syntax. The syntax is based on the QueryDSL predicate API, which provides a rich set of operators and functions for constructing complex query expressions. To use QueryDSL HTTP query parameter, clients can append query parameters to the REST API endpoint, using the following syntax:
[base-uri]/entities?[query-parameter]
For example, if we have a Spring Data REST application that exposes a REST API for managing cars, we can use QueryDSL HTTP query parameter to search for cars with a specific purchase date range:
http://localhost:8080/cars?purchaseDate.between(2020-01-01, 2020-12-31)
Spring Data REST Application with QueryDSL
Let's consider a Spring Data REST application that manages a list of cars. The Car entity has a purchaseDate field, which we want to use for querying the cars:
@Entity
public class Car {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String make;
private String model;
private LocalDate purchaseDate;
// getters and setters
}
To enable QueryDSL support for the Car entity, we need to add the following dependencies to our Maven pom.xml file:
<dependency>
<groupId>com.querydsl</groupId>
<artifactId>querydsl-jpa</artifactId>
<version>5.0.0</version>
</dependency>
<dependency>
<groupId>com.querydsl</groupId>
<artifactId>querydsl-apt</artifactId>
<version>5.0.0</version>
<scope>provided</scope>
</dependency>
We also need to configure Spring Data REST to use QueryDSL by adding the following configuration to our Spring configuration file:
@Configuration
@EnableSpringDataWebSupport
public class QueryDslConfig extends RepositoryRestConfigurerAdapter {
@Override
public void configureRepositoryRestConfiguration(RepositoryRestConfiguration config) {
config.setBasePath("/api");
config.setDefaultMediaType(MediaTypes.HAL_JSON);
config.addRestConverter(new QuerydslAwareMvcJsonHttpMessageConverter());
}
}
Now we can use QueryDSL HTTP query parameter to search for cars with a specific purchase date range:
http://localhost:8080/api/cars?purchaseDate.between(2020-01-01, 2020-12-31)
Spring Data REST and QueryDSL are powerful frameworks that simplify the development of RESTful services for Spring-based applications. By using QueryDSL HTTP query parameter, clients can specify query criteria using a simple and intuitive syntax, which can then be translated into various query languages. This allows developers to build complex query capabilities into their RESTful services, without requiring clients to learn complex query languages or APIs.
References
- Spring Data REST: https://spring.io/projects/spring-data-rest
- QueryDSL: https://querydsl.com/
- Spring Data REST and QueryDSL: https://spring.io/blog/2019/03/12/spring-data-rest-3-1-querydsl-support