Question

这是存储库：

@Query(value = "select u.balance from User u where u.name=:name")
float toGetBalance(@Param("name") String name);

这是DAO界面：

boolean checkBalance(String userName, float totalPrice);

这是服务

@Transactional(readOnly = true)
@Override
public boolean checkBalance(String userName, float totalPrice) {

    if (userRepository.toGetBalance(userName) < totalPrice) {

        return false;

    } else {

        return true;

    }

}

，这是错误信息：

org.springframework.aop.AopInvocationException: Null return value from advice does not match primitive return type for: public abstract float com.repository.UserRepository.toGetBalance(java.lang.String)

并且余额的类型是浮动的！

出了什么问题？

Answer 1

将存储库的签名更改为

items fetched. testing Optional("my name 1"), myField2 Optional("1"), whose image is    
External Data Reference: <self = 0x1702940f0 ; path = nil ; length = 13127>

items fetched. testing Optional("my Name 2"), myField2 Optional("1"), whose image is
    External Data Reference: <self = 0x170294140 ; path = 735DB08E-2727-4F01-91C9-914C8A3DD170 ; length = 6826295>

如果在给定@Query(value = "select u.balance from User u where u.name=:name") Float toGetBalance(@Param("name") String name);

的数据库中没有此类用户，它将只返回null

Answer 2

@Query(value = "select u.balance from User u where u.name=:name")' 'Float toGetBalance(@Param("name") String name);

出现此异常是因为名称不存在或余额= NULL如果表中的所选记录是因此查询结果没有输出。 Spring JPA无法将结果绑定为返回类型Float。

Null return value from advice does not match primitive return type for: public abstract float com.repository.UserRepository.toGetBalance(java.lang.String)

aop.AopInvocationException：Null返回值

2 个答案: