如何在 Spring Data rest 中返回 List<String> 或 String

Question

我正在为我的应用程序使用 Spring Data rest。

我在我的存储库中使用以下方法。

public interface TestRepository() extends BaseRepository<TestTerm, Integer>{
    @Query("select distinct tt.term from TestTerm")
        List<String> findDistinctTerm();
}

当我执行上述方法时。我收到以下错误

PersistentEntity must not be null

与Spring Data Rest (SDR ) bug? Persistent Entity Must not be null相关的问题

我该如何解决这个问题？

我必须为此编写单独的实现吗？如果是这样，任何人都可以为我举个例子吗？

更新：-

我试过这样

方法一：-

@Query("select DISTINCT term from ForbiddenTerm")
List<TestTerm> findDistinctByTerm();

错误：-

{ “原因”：空， "message": "PersistentEntity 不能为空！" }

方法二：-

List<TestTerm> findDistinctByTerm();

错误：-

    ... 154 common frames omitted
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.data.repository.support.Repositories]: Factory method 'repositories' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'forbiddenTermRepository': Invocation of init method failed; nested exception is java.util.NoSuchElementException
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:189) ~[spring-beans-4.3.3.RELEASE.jar!/:4.3.3.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:588) ~[spring-beans-4.3.3.RELEASE.jar!/:4.3.3.RELEASE]
    ... 175 common frames omitted
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'forbiddenTermRepository': Invocation of init method failed; nested exception is java.util.NoSuchElementException

Answer 1

您需要像这样更改界面的名称：

@Repository
public interface TestTermRepository() extends BaseRepository<TestTerm, Integer>{
@Query("select distinct tt.term from TestTerm")
    List<String> findDistinctTerm();
}

你还需要添加@Repository注解