来自字段 Spring Data 和 Mongodb 的最大值 [英] Max value from field Spring Data and Mongodb

问题描述

我想计算实体User"中字段代码的最大值，使用Spring Data，我看到代码如下:

I want to calculate the maximum value of the field code within my entity "User", use Spring Data, I have seen that the code is as:

".find({}).sort({"updateTime" : -1}).limit(1)"

但我不知道如何使用@Query 将其集成到我的存储库"中

But I do not know how to integrate it into my "repository" with @Query

或者其他等效的解决方案，而不是返回所述字段的最大值.有人可以帮助我吗?谢谢.

Or another equivalent solution, than to return the maximum value of said field. Can somebody help me? Thank you.

推荐答案

您可以为您的存储库编写自定义方法.例如你有:

You can write a custom method for your repository. For example you have:

public interface UserRepository extends MongoRepository<User, String>, UserRepositoryCustom {
...
}

存储库的其他方法:

public interface UserRepositoryCustom {
    User maxUser();
}

然后实现它:

public class UserRepositoryImpl implements UserRepositoryCustom { 
    @Autowired
    private MongoTemplate mongoTemplate;

    @Override
    public User maxUser() {
        final Query query = new Query()
                .limit(1)
                .with(new Sort(Sort.Direction.DESC, "updateTime"));

        return mongoTemplate.findOne(query, User.class)
    }
}

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