使用 OneToMany 的 Spring Boot JPA 自定义查询

Question

我正在 Spring Boot 中构建一个类似 Twitter 的应用程序。我正在尝试为用户生成时间线。我为此做了一个自定义查询并将其添加到我的repository 中，它扩展了CrudRepository<Account, Long>。当我尝试启动应用程序时，我收到以下异常：

Caused by: org.hibernate.hql.internal.ast.QuerySyntaxException: account_following is not mapped

account_following 表是从Account 到Account 的@OneToMany，如下面的代码所示。我不确定如何将account_following 放入查询中。

AccountRepository.java

@Repository
public interface AccountRepository extends CrudRepository<Account, Long> {

    @Query("SELECT t FROM Tweet t, account_following k WHERE k.following_id = t.owner_id AND k.account_ID = :account_ID AND k.following_id IN (SELECT following_ID FROM account_following WHERE account_id = :account_ID) ORDER BY unixdate DESC")
    public List<Tweet> generateTimeline(@Param("account_ID") Long account_ID);

}

Account.java

@Entity
public class Account implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @Column(unique=true)
    private String username;

    @Transient
    private String password;

    private String location;

    private String description;

    private String website;

    @OneToMany(cascade = CascadeType.ALL)
    private List<Account> following;

    @OneToMany(mappedBy = "owner", cascade = CascadeType.ALL)
    private List<Tweet> tweets;
}

Pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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>
    <artifactId>kwetter</artifactId>
    <groupId>org.springframework</groupId>
    <version>0.1.0</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.4.RELEASE</version>
    </parent>

    <dependencies>

        <!--Spring Boot-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <type>jar</type>
        </dependency>

        <!--JAVAX-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <type>jar</type>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
            <type>jar</type>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>5.0.8.RELEASE</version>
            <scope>test</scope>
            <type>jar</type>
        </dependency>
        <dependency>
            <groupId>javax</groupId>
            <artifactId>javaee-web-api</artifactId>
            <version>7.0</version>
            <type>jar</type>
        </dependency>

        <!--DB-->
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>eclipselink</artifactId>
            <version>2.5.2</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>org.eclipse.persistence.jpa.modelgen.processor</artifactId>
            <version>2.5.2</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>


    </dependencies>

    <properties>
        <java.version>1.8</java.version>
    </properties>


    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

表account_following 存在于数据库中，如下图所示。我正在使用MySQL version 8.0.12。

Answer 1

尝试将查询更改为原生查询。

@Repository
public interface AccountRepository extends CrudRepository<Account, Long> {

@Query(value= "SELECT t FROM Tweet t, account_following k WHERE k.following_id = t.owner_id AND k.account_ID = :account_ID AND k.following_id IN (SELECT following_ID FROM account_following WHERE account_id = :account_ID) ORDER BY unixdate DESC",nativeQuery=true)
public List<Tweet> generateTimeline(@Param("account_ID") Long account_ID);
}

由于没有名为 account_following 的实体，您会在 HQL 中收到该错误。

Answer 2

如果 JPQL：

SELECT t FROM Tweet as t, Account as account WHERE account.following as f on f.id = t.ownerId ...

请注意，以上字段必须与类字段相同，而不是数据库中的列名。