Java Spring数据JPA中@ManyToMany关系的查询方法

我有实体用户和对话，它们之间的关系为@ManyToMany:

@Entity
@Table(name="USER")
public class User {
    ...
    ...
    @ManyToMany
    @JoinTable(name="USER_CONVERSATION",
            joinColumns = @JoinColumn(name = "user_id"),
            inverseJoinColumns = @JoinColumn(name = "conversation_id"))
    Set<Conversation> conversations = new HashSet<>();
    ...
    ...
}

---

我没有任何错误？用户是设置的，而不是单个元素，那么该查询在做什么呢？

您可以将OrderByUsers添加到方法中并删除参数，而不是执行如此复杂的操作。因此，您应该有类似于列表findAllByOrderByUsers的内容；这样你就可以得到你想要的结果。

---

还要注意，By是为了替换对话，我遇到了同样的问题，为了解决这个问题，我在方法的末尾添加了In后缀。比如：

List<Conversation> findAllConversationsByUsersIn(List<User> users);

---

这取决于查询应该做什么：获取至少有一个给定用户的所有对话，或者获取包含所有给定用户的对话，或者获取包含给定用户的对话。但无论如何，您不应该害怕使用查询。在大多数情况下，这是正确的做法。我需要与给定用户进行详细的对话。然后您需要编写一个带有子查询的查询。它应该找到所有用户总数等于属于给定列表的会话用户数的会话。您能给出创建该查询的建议吗？我对此有问题。这应该可以工作：从对话c中选择c，其中sizec.users=从对话c2中选择countu2.id加入c.users u，其中c2.id=c.id和u2在：usersokay中，如果我想要精确匹配，情况如何？我必须写一个查询吗？或者是否还有一些可用于此目的的存储库关键字？@monslgnore与列表完全匹配？或者一个值？与列表完全匹配；所以，仅当列表参数中包含的所有对象也包含在实体列表中时，才返回实体attribute@monsIgnore我不知道有什么关键字可以用。如果列表大小固定且较短，我将使用item1=？1和。。。。因为简单。如果列表大小可变，我将使用规范Api。

public interface ConversationRepository extends JpaRepository<Conversation, Long> {

    List<Conversation> findAllConversationsByUsers(List<User> users);

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'conversationRepository': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Failed to create query for method public abstract java.util.List pl.teamvi.project.repositories.ConversationRepository.findAllConversationsByUsers(java.util.List)! Operator SIMPLE_PROPERTY on users requires a scalar argument, found interface java.util.List in method public abstract java.util.List pl.teamvi.project.repositories.ConversationRepository.findAllConversationsByUsers(java.util.List).
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1796) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:595) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:207) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1114) ~[spring-context-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.data.repository.support.Repositories.cacheRepositoryFactory(Repositories.java:99) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.repository.support.Repositories.populateRepositoryFactoryInformation(Repositories.java:92) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.repository.support.Repositories.<init>(Repositories.java:85) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.rest.webmvc.config.RepositoryRestMvcConfiguration.repositories(RepositoryRestMvcConfiguration.java:212) ~[spring-data-rest-webmvc-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.data.rest.webmvc.config.RepositoryRestMvcConfiguration$$EnhancerBySpringCGLIB$$f3b0aabb.CGLIB$repositories$51(<generated>) ~[spring-data-rest-webmvc-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.data.rest.webmvc.config.RepositoryRestMvcConfiguration$$EnhancerBySpringCGLIB$$f3b0aabb$$FastClassBySpringCGLIB$$4b18e8f9.invoke(<generated>) ~[spring-data-rest-webmvc-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244) ~[spring-core-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:363) ~[spring-context-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.data.rest.webmvc.config.RepositoryRestMvcConfiguration$$EnhancerBySpringCGLIB$$f3b0aabb.repositories(<generated>) ~[spring-data-rest-webmvc-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_201]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_201]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_201]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_201]
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    ... 142 common frames omitted
Caused by: java.lang.IllegalArgumentException: Failed to create query for method public abstract java.util.List pl.teamvi.project.repositories.ConversationRepository.findAllConversationsByUsers(java.util.List)! Operator SIMPLE_PROPERTY on users requires a scalar argument, found interface java.util.List in method public abstract java.util.List pl.teamvi.project.repositories.ConversationRepository.findAllConversationsByUsers(java.util.List).
    at org.springframework.data.jpa.repository.query.PartTreeJpaQuery.<init>(PartTreeJpaQuery.java:102) ~[spring-data-jpa-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$CreateQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:106) ~[spring-data-jpa-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$CreateIfNotFoundQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:211) ~[spring-data-jpa-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$AbstractQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:79) ~[spring-data-jpa-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lookupQuery(RepositoryFactorySupport.java:574) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lambda$mapMethodsToQuery$1(RepositoryFactorySupport.java:567) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193) ~[na:1.8.0_201]
    at java.util.Iterator.forEachRemaining(Iterator.java:116) ~[na:1.8.0_201]
    at java.util.Collections$UnmodifiableCollection$1.forEachRemaining(Collections.java:1049) ~[na:1.8.0_201]
    at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801) ~[na:1.8.0_201]
    at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481) ~[na:1.8.0_201]
    at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471) ~[na:1.8.0_201]
    at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708) ~[na:1.8.0_201]
    at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:1.8.0_201]
    at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499) ~[na:1.8.0_201]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.mapMethodsToQuery(RepositoryFactorySupport.java:569) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lambda$new$0(RepositoryFactorySupport.java:559) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at java.util.Optional.map(Optional.java:215) ~[na:1.8.0_201]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.<init>(RepositoryFactorySupport.java:559) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport.getRepository(RepositoryFactorySupport.java:332) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.lambda$afterPropertiesSet$5(RepositoryFactoryBeanSupport.java:297) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.util.Lazy.getNullable(Lazy.java:212) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.util.Lazy.get(Lazy.java:94) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.afterPropertiesSet(RepositoryFactoryBeanSupport.java:300) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.jpa.repository.support.JpaRepositoryFactoryBean.afterPropertiesSet(JpaRepositoryFactoryBean.java:121) ~[spring-data-jpa-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1855) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1792) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    ... 163 common frames omitted
Caused by: java.lang.IllegalStateException: Operator SIMPLE_PROPERTY on users requires a scalar argument, found interface java.util.List in method public abstract java.util.List pl.teamvi.project.repositories.ConversationRepository.findAllConversationsByUsers(java.util.List).
    at org.springframework.data.jpa.repository.query.PartTreeJpaQuery.throwExceptionOnArgumentMismatch(PartTreeJpaQuery.java:177) ~[spring-data-jpa-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.jpa.repository.query.PartTreeJpaQuery.validate(PartTreeJpaQuery.java:153) ~[spring-data-jpa-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.jpa.repository.query.PartTreeJpaQuery.<init>(PartTreeJpaQuery.java:96) ~[spring-data-jpa-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    ... 189 common frames omitted 

List<Conversation> findAllConversationsByUsers(User users);

List<Conversation> findAllConversationsByUsersIn(List<User> users);