Spring Data JPA自定义存储库，如何应用逻辑 [英] Spring data JPA custom repository, how apply logic

问题描述

我尝试实现JPA自定义存储库.

I try to implement a JPA custom repository.

我有一个这样的过滤器对象:

I have a filter object like this:

public class FilterPatient {
    private String surname;
    private String name;
    private String cf;

    ... and so on
}

从前端，我根据用户输入创建一个FilterPatient实例.

From front end I create an instance of FilterPatient based on user input.

例如，用户可以对姓氏和cf属性或姓氏和名称等进行赋值

So, user, for example, can value surname and cf properties or surname and name, and so on

我要实现一个自定义存储库，如下所示:

I want to implement a custom repository as follow:

PatientRepository extends JpaRepository<Patient, Long> {
    List<Patient> findBySurname(String surname);

    List<Patient> findByName(String name);

    List<Patient> findByCf(String cf);

    // custom methods:
    @Query("select p from Patient p where p.name = :name
        and p.surname = :surname")
    List<Patient> findByNameAndSurname(@Param("name") String name,
          @Param("surname") String surname);

    ... and so on
}

问题:

基于用户输入，我必须执行一个不同的查询，那么如何管理存储库?我必须编写查询方法以涵盖输入字段的不同组合，并且必须在服务中编写有关方法存储库调用的逻辑?还是我可以更好地自定义方法查询的参数设置?

Based on user input I must execute a different query, so how I manage the repository? I must write query methods to cover different combinations of input field and in the service I must write the logic about method repository call? Or I can parametrize better my custom method query?

其他信息:

通常没有spring-data，我用输入参数FilterPatient定义了一个DAO方法，因此我基于不为null的参数构建查询，然后用query.setString方法替换参数.通过这种方式，我编写了一个通用方法，Spring-data和JPA存储库是否可能?

Without spring-data normally, I define a DAO method with input parameter FilterPatient, so I build a query based on parameter not null and then I substitute parameter with query.setString method. In this way I write one generic method, is it possible with Spring-data and JPA repositories?

编辑

按用户查询示例

SELECT FROM Patient p WHERE p.name = :name
AND p.surname = :surname
AND p.cf = :cf

和其他可能的配置，例如，在FilterPatient IS NULL的cf属性中，查询将变为:

and other possible configuration, for example, in cf property of FilterPatient IS NULL, the query will become:

SELECT FROM Patient p WHERE p.name = :name
AND p.surname = :surname

推荐答案

您正在寻找的是规范模式，该模式将在以下针对Spring Data JPA进行讨论:

What you are looking for is the Specification pattern which is discussed in relation to Spring Data JPA at the following:

https://spring.io/blog/2011/04/26/advanced-spring-data-jpa-specifications-and-querydsl/

，以及有关每个查询具有查询方法的注意事项:

and which notes with reference to having a query method per query:

尽管这种方法确实很方便(您甚至不必 编写一行实现代码以获取查询 执行)有两个缺点:首先，查询方法数量众多 可能会因为以下原因而在更大的应用程序中增长-这是第二个 点-查询定义了一组固定的条件.为了避免这些 有两个缺点，如果您能提出一套 您可以动态组合以建立自己的原子谓词 查询?

Although this approach is really convenient (you don’t even have to write a single line of implementation code to get the queries executed) it has two drawbacks: first, the number of query methods might grow for larger applications because of - and that’s the second point - the queries define a fixed set of criterias. To avoid these two drawbacks, wouldn’t it be cool if you could come up with a set of atomic predicates that you could combine dynamically to build your query?

您可以使用JPA标准API或QueryDSL来实现规范"模式.使用后者，就像让您的存储库扩展以下界面一样简单:

You can implement the Specification pattern using either the JPA criteria API or using QueryDSL. Using the latter this is as easy as having your repository extend the following interface:

http ://docs.spring.io/spring-data/commons/docs/current/api/org/springframework/data/querydsl/QueryDslPredicateExecutor.html

，并将对Querydsl的支持添加到您的项目中.对于Maven项目，您只需要将以下配置添加到POM.该插件将自动生成构造谓词所需的Query类，然后您可以使用任何参数组合调用存储库中的以下方法:

and adding support for Querydsl to your project. For a Maven project you simply need to add the configuration below to your POM. The plugin will auto generate the Query classes required to construct the predicates and you can then call the following methods of your Repository with any combination of parameters:

Iterable<T> findAll(com.querydsl.core.types.OrderSpecifier<?>... orders)
Iterable<T> findAll(com.querydsl.core.types.Predicate predicate)
Iterable<T> findAll(com.querydsl.core.types.Predicate predicate, com.querydsl.core.types.OrderSpecifier<?>... orders)
Page<T> findAll(com.querydsl.core.types.Predicate predicate, Pageable pageable)
Iterable<T> findAll(com.querydsl.core.types.Predicate predicate, Sort sort)
T   findOne(com.querydsl.core.types.Predicate predicate)

使用这种方法，您的PatientRepository就会变得简单:

With this approach then your PatientRepository becomes simply:

PatientRepository extends JpaRepository<Patient, Long>, QueryDslLPredicateExecutor<Patient> {
   // no query methods needed
}

请注意，Spring Data Gosling发行版还添加了对将HTTP参数自动绑定到QueryDSL谓词的支持，因此您还可以删除过滤器，并让Spring Data端到端处理所有内容.

Note that the Spring Data Gosling release also added support for automatically binding HTTP params to a QueryDSL Predicate so you could also remove your Filter and have Spring Data handle everything end-to-end.

这里有一些示例显示了一种使用各种参数调用的查询方法:

There are some examples here showing 1 query method being called with various parameters:

https://stackoverflow.com/a/26450224/1356423

Maven设置:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    .....

    <properties>
        <querydsl.version>4.1.3</querydsl.version>
    </properties>

    <dependencies>

        .....

        <dependency>
            <groupId>com.querydsl</groupId>
            <artifactId>querydsl-jpa</artifactId>
            <version>${querydsl.version}</version>
        </dependency>
        <dependency>
            <groupId>com.querydsl</groupId>
            <artifactId>querydsl-apt</artifactId>
            <version>${querydsl.version}</version>
        </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/java</outputDirectory>
                            <processor>com.querydsl.apt.jpa.JPAAnnotationProcessor</processor>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

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