如何使用Querydsl和Spring Data轻松实现"REST API查询语言"以过滤实体? [英] How to easy implement 'REST API query language' with Querydsl and Spring Data to filter the entities?

问题描述

如何使用 Spring Data 轻松实现一种"REST API查询语言"以过滤实体?

How to easy implement a kind of 'REST API query language' with Spring Data to filter the entities?

例如，对于以下Person实体:

@Data
@Entity
public class Person {

  @Id
  @GeneratedValue
  private Long id;

  private LocalDate dob; // date of birth

  private String name;

  @Formula("timestampdiff('year', dob, now())")
  private Integer age;

  public Person(String name, LocalDate dob) {
    this.name = name;
    this.dob = dob;
  }
}

我想通过这样的请求获取其数据:

I would like to get its data with such a request:

GET /people?name=jo&age=18&page=1&sort=name,desc

即:获取所有name包含"jo"(不区分大小写)且age等于18的所有人的第一页，并按name降序排列."

I.e.: 'get the 1st page of all people whose name contains "jo" (case insensitive) and whose age is equal to 18, sorting by name in descending order'.

推荐答案

在

With help of Querydsl Web Support, the part of Web support Spring Data extension, we can easy implement a kind of 'REST API query language' to filter our entities.

我们所需要做的是执行以下操作:

All we need is do the following:

1)从QuerydslPredicateExecutor扩展

2)将带有注释@QuerydslPredicate的Predicate作为参数添加到我们的REST控制器方法

2) add Predicate with annotation @QuerydslPredicate, as argument, to our REST controller method

3)在存储库的findAll方法中使用此谓词:

3) use this predicate in findAll method of the repository:

public interface PersonRepo extends JpaRepository<Person, Long>, QuerydslPredicateExecutor<Person> {
} 

@RequiredArgsConstructor
@RestController
@RequestMapping("/people")
public class PersonController {

    private final PersonRepo personRepo;

    @GetMapping
    public ResponseEntity getFiltered(@QuerydslPredicate(root = Person.class) Predicate predicate, Pageable pageable) {
        return ResponseEntity.ok(personRepo.findAll(predicate, pageable)));
    }
}

然后我们将能够请求我们的数据:

Then we will be able to request our data:

GET /people?name=John&age=18&page=1&sort=name,desc

接下来，我们必须创建不区分大小写的喜欢"过滤器.为此，我们从QuerydslBinderCustomizer扩展了仓库，并覆盖了customize方法(在仓库中):

Next we have to make case insensitive 'like' filter. To do this we extend our repo from QuerydslBinderCustomizer and override its customize method (right in the repo):

public interface PersonRepo extends
        JpaRepository<Person, Long>,
        QuerydslPredicateExecutor<Person>,
        QuerydslBinderCustomizer<QPerson> {

    @Override
    default void customize(QuerydslBindings bindings, QPerson person) {

        // Make case-insensitive 'like' filter for all string properties 
        bindings.bind(String.class).first((SingleValueBinding<StringPath, String>) StringExpression::containsIgnoreCase);
    }
}

要使其正常工作，我们必须在控制器方法的@QuerydslPredicate中添加参数bindings:

To make it works we have to add parameter bindings to @QuerydslPredicate of our controller method:

@GetMapping
public ResponseEntity getFiltered(
    @QuerydslPredicate(root = Person.class, bindings = PersonRepo.class) Predicate predicate, 
    Pageable pageable
) {
    return ResponseEntity.ok(personRepo.findAll(predicate, pageable)));
}

现在，我们可以按照问题中的要求索取数据了:

Now we can request our data as asked in the question:

GET /people?name=jo&age=18&page=1&sort=name,desc

使用QuerydslBinderCustomizer，我们可以实现更复杂的过滤器，例如between和greater or equal过滤器(将此代码添加到customize方法中):

With QuerydslBinderCustomizer we can implement more complex filters, for example between and greater or equal filters (add this code to customize method):

bindings.bind(person.age).all((path, value) -> {
    Iterator<? extends Integer> it = value.iterator();
    Integer from = it.next();
    if (value.size() >= 2) {
        Integer to = it.next();
        return Optional.of(path.between(from, to)); // between
    } else {
        return Optional.of(path.goe(from)); // greater or equal
    }
});

如果我们在请求中指定了两个age参数，那么我们将获得所有记录，这些记录的年龄在之间.如果仅指定一个age参数-我们将获得年龄大于或等于该值的记录.

If we specify two age parameters in the request then we get all records with the age between these parameters. If we specify only one age parameter - we get records with the age is greater or equal that value.

GET /people?age=18&age=30

... 获取所有18至30岁的人

GET /people?age=18

... 获取所有年龄大于或等于18岁的人

最后，我们可以从过滤器中排除一些不必要的属性，例如实体id(将此代码添加到customize方法中):

In the end we can exclude some unnecessary properties from the filter, for example the entity id (add this code to customize method):

bindings.excluding(person.id);

要使用Querydsl Web支持，我们必须将以下依赖项和插件添加到我们的Spring Boot项目中:

To use Querydsl Web Support we have to add these dependencies and plugin to our Spring Boot project:

<dependencies>
    <!-- ... -->

    <dependency>
        <groupId>com.querydsl</groupId>
        <artifactId>querydsl-jpa</artifactId>
    </dependency>

    <dependency>
        <groupId>com.querydsl</groupId>
        <artifactId>querydsl-apt</artifactId>
        <scope>provided</scope>
    </dependency>
</dependencies>

<build>
    <plugins>
        <!-- ... -->

        <plugin>
            <groupId>com.mysema.maven</groupId>
            <artifactId>apt-maven-plugin</artifactId>
            <version>1.1.3</version>
            <executions>
                <execution>
                    <goals>
                        <goal>process</goal>
                    </goals>
                    <configuration>
                        <outputDirectory>target/generated-sources/annotations</outputDirectory>
                        <processor>com.querydsl.apt.jpa.JPAAnnotationProcessor</processor>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

然后，重要的是，编译项目以构建实体的"Q类".

Then, it's important, compile the project to build 'Q-classes' of our entities.

您可以在我的仓库中找到完整的示例演示: sb-querydsl-sd-demo 和邮递员此演示的API文档-此处:

Full example demo you can find in my repo: sb-querydsl-sd-demo, and Postman API-docs of this demo - here: REST query language with Querydsl and Spring Data.

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