如何查询复合主键的子集？

Question

我有以下课程：

@Entity
@Table(name = "my_entity")
@JsonIgnoreProperties(ignoreUnknown = true)
public class MyEntity {
    @EmbeddedId
    private Pk id;

    public Pk getId() {
        return id;
    }

    public void setId(Pk id) {
        this.id = id;
    }

}

@Embeddable
public class Pk implements Serializable {
    private static final long serialVersionUID = -3090221844117493661L;
    private Integer type;
    private String userId;

    public Pk() {
    }

    public Pk(String userId, Integer type) {
        this.setUserId(userId);
        this.setType(type);
    }

    public Integer getType() {
        return type;
    }

    public String getUserId() {
        return userId;
    }

    public void setType(Integer type) {
        this.type = type;
    }

    public void setUserId(String userId) {
        this.userId = userId;
    }

    // Auto-generated by Eclipse.
    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((type == null) ? 0 : type.hashCode());
        result = prime * result + ((userId == null) ? 0 : userId.hashCode());
        return result;
    }

    // Auto-generated by Eclipse.
    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Pk other = (Pk) obj;
        if (type != other.type)
            return false;
        if (userId == null) {
            if (other.userId != null)
                return false;
        } else if (!userId.equals(other.userId))
            return false;
        return true;
    }

}

public interface MyEntityRepository extends JpaRepository<MyEntity, Pk> {

    List<MyEntity> findAllByUserId(String userId);

}

当我初始化 Spring Data JPA 时出现错误：

Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'myEntityRepository': Invocation of init method failed; nested exception is org.springframework.data.mapping.PropertyReferenceException: No property user found for type MyEntity!
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1512)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:521)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:296)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:293)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:615)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:932)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479)
    at org.springframework.context.annotation.AnnotationConfigApplicationContext.<init>(AnnotationConfigApplicationContext.java:73)
    at com.myproject.backend.common.ServiceContext.start(ServiceContext.java:293)
    at com.myproject.run(AbstractServiceContainer.java:55)
    at com.myproject..run(AbstractServiceContainer.java:1)
    at io.dropwizard.cli.EnvironmentCommand.run(EnvironmentCommand.java:42)
    at io.dropwizard.cli.ConfiguredCommand.run(ConfiguredCommand.java:76)
    at io.dropwizard.cli.Cli.run(Cli.java:70)
    at io.dropwizard.Application.run(Application.java:72)
    at com.myproject..main(CombinedServiceContainer.java:106)
Caused by: org.springframework.data.mapping.PropertyReferenceException: No property user found for type MyEntity!
    at org.springframework.data.mapping.PropertyPath.<init>(PropertyPath.java:75)
    at org.springframework.data.mapping.PropertyPath.create(PropertyPath.java:327)
    at org.springframework.data.mapping.PropertyPath.create(PropertyPath.java:359)
    at org.springframework.data.mapping.PropertyPath.create(PropertyPath.java:307)
    at org.springframework.data.mapping.PropertyPath.from(PropertyPath.java:270)
    at org.springframework.data.mapping.PropertyPath.from(PropertyPath.java:241)
    at org.springframework.data.repository.query.parser.Part.<init>(Part.java:76)
    at org.springframework.data.repository.query.parser.PartTree$OrPart.<init>(PartTree.java:213)
    at org.springframework.data.repository.query.parser.PartTree$Predicate.buildTree(PartTree.java:321)
    at org.springframework.data.repository.query.parser.PartTree$Predicate.<init>(PartTree.java:301)
    at org.springframework.data.repository.query.parser.PartTree.<init>(PartTree.java:85)
    at org.springframework.data.jpa.repository.query.PartTreeJpaQuery.<init>(PartTreeJpaQuery.java:60)
    at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$CreateQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:91)
    at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$CreateIfNotFoundQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:168)
    at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$AbstractQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:69)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.<init>(RepositoryFactorySupport.java:320)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport.getRepository(RepositoryFactorySupport.java:169)
    at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.initAndReturn(RepositoryFactoryBeanSupport.java:224)
    at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.afterPropertiesSet(RepositoryFactoryBeanSupport.java:210)
    at org.springframework.data.jpa.repository.support.JpaRepositoryFactoryBean.afterPropertiesSet(JpaRepositoryFactoryBean.java:92)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1571)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1509)
    ... 18 more

问题：Spring Data JPA 不支持查询主键的子集吗？或者我需要为此实现自定义存储库方法吗？

Answer 1

您需要告诉 JPA 在哪里查找 userId 字段（即在嵌入的 id 中）。 如果您将存储库方法的名称更改为findAllByIdUserId，它应该可以工作。

Answer 2

好的，我也尝试使用 @IdClass 来代替：

@Entity
@Table(name = "my_entity")
@JsonIgnoreProperties(ignoreUnknown = true)
@IdClass(Pk.class)
public class MyEntity {
    @Id private Integer type;
    @Id private String userId;

    public Pk getId() {
        return id;
    }

    public void setId(Pk id) {
        this.id = id;
    }

}

@IdClass(Pk.class)
public class Pk implements Serializable {
    private static final long serialVersionUID = -3090221844117493661L;
    private Integer type;
    private String userId;

    public Pk() {
    }

    public Pk(String userId, Integer type) {
        this.setUserId(userId);
        this.setType(type);
    }

    public Integer getType() {
        return type;
    }

    public String getUserId() {
        return userId;
    }

    public void setType(Integer type) {
        this.type = type;
    }

    public void setUserId(String userId) {
        this.userId = userId;
    }

    // Auto-generated by Eclipse.
    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((type == null) ? 0 : type.hashCode());
        result = prime * result + ((userId == null) ? 0 : userId.hashCode());
        return result;
    }

    // Auto-generated by Eclipse.
    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Pk other = (Pk) obj;
        if (type != other.type)
            return false;
        if (userId == null) {
            if (other.userId != null)
                return false;
        } else if (!userId.equals(other.userId))
            return false;
        return true;
    }

}

这确实给了我一条不同的错误消息，NullPointerException，这暗示我 Spring Data JPA 无法为 findAllByUserId(...) 构建查询。我对那个查询方法做了一个自定义实现：

public interface MyEntityRepository extends JpaRepository<MyEntity, Pk>, MyEntityRepositoryCustom {

}

public interface MyEntityRepositoryCustom {

    List<MyEntity> findAllByUserId(String userId);

}

public class MyEntityRepositoryImpl implements MyEntityRepositoryCustom {

    @PersistenceContext
    private EntityManager em;

    @Override
    public List<MyEntityRepositoryCustom> findAllByUserId(String userId) {
        return em
                .createQuery("select o from MyEntity o where o.userId=:userId",
                        MyEntity.class).setParameter("userId", userId).getResultList();
    }

}

...瞧，它有效！