Spring + MongoDB 标记 @Query 与 $group 不工作

Question

注意：向下查看编辑后的消息。

我正在尝试模仿这个查询：

db.sentiments.aggregate([
{"$group" : {_id:{theme_id:"$theme",sentiment_id:"$sentiment"}, count:{$sum:1}}},
{"$sort":{"_id.theme_id":1}} ])

这是我为模仿它而生成的代码：

    @RepositoryRestResource(collectionResourceRel = "sentiments", path = "sentiments")
public interface SentimentsRepository extends MongoRepository<Sentiments, String> {
    Long countByTheme(@Param("theme") String theme);

@Query(value ="[\n" +
        "    {\"$group\" : {_id:{theme_id:\"$theme\",sentiment_id:\"$sentiment\"}, count:{$sum:1}}},\n" +
        "\t{\"$sort\":{\"_id.theme_id\":1}}\n" +
        "]",count = true)
List<Object> comptarSentiments();

} 那么这段代码返回给我这个错误：

"exception": "org.springframework.data.mongodb.UncategorizedMongoDbException",


"message": "Can't canonicalize query: BadValue unknown operator: $group; nested exception is com.mongodb.MongoException: Can't canonicalize query: BadValue unknown operator: $group",

其实我是Spring的初学者，所以我很迷茫，有人知道我该怎么办吗？

感谢和抱歉我的英语不好，不是我的母语。

[编辑]---------------------------------------- 正如 Shawn Clark 所写的评论那样，这样做是不可能的，为了实现这一点，您需要创建一个 customRepository。

What's the difference between Spring Data's MongoTemplate and MongoRepository?

我一直在尝试这样做，但似乎有些不正确，这是我的新代码：

@RepositoryRestResource(collectionResourceRel = "sentiments", path = "sentiments")
public interface SentimentsRepository extends CrudRepository<Sentiments, String>, CustomSentimentsRepository {

//Other methods...

}

public interface CustomSentimentsRepository {

    List<CountResult> yourCustomMethod();

    class CountResult{
        String theme;
        String sentiment;
        int total;
    }
}

public class SentimentsRepositoryImpl implements CustomSentimentsRepository {
    private final MongoOperations operations;


    @Autowired
    public SentimentsRepositoryImpl(MongoOperations operations) {

        Assert.notNull(operations, "MongoOperations must not be null!");
        this.operations = operations;
    }

    @Override
    public List<CountResult> yourCustomMethod(){
        Aggregation agg = Aggregation.newAggregation(
                Aggregation.group("theme","sentiment").count().as("total"),
                Aggregation.project("theme","sentiment").and("total").previousOperation(),
                Aggregation.sort(Sort.Direction.DESC, "theme")
        );

        //Convert the aggregation result into a List
        AggregationResults<CountResult> groupResults
                = operations.aggregate(agg,"sentiments",  CountResult.class);
        //List<CountResult> result = groupResults.getMappedResults();

        return groupResults.getMappedResults();
    }
}

我什至无法调试这段代码，而且总是得到 404。

Answer 1

根据我发现的信息，您无法在 MongoRepository 方法上执行 @Query 的复杂操作。在这种情况下，您需要创建一个类并使用 mongoTemplate 实现您的 comptarSentiments() 方法，以使用您的聚合函数查询数据存储。然后创建一个公开 REST 端点的控制器类并让它调用存储库。

一旦您开始在 Mongo 中执行复杂的查询，您就会失去 @RepositoryRestResource 的便利性，并且必须自己重新将 REST 端点连接到存储库。

Spring Data REST : custom query for MongoDB repository

Implementing custom methods of Spring Data repository and exposing them through REST

Answer 2

我终于设法解决了这个问题，似乎它与控制器和innerClass CountResult中的属性“total”的类型有关，它需要是一个String（这很重要，否则Aggregation.project将失败）。最终代码如下：

public interface CustomSentimentsRepository {

    List<CountResult> myCountGroupByThemeAndSentiment();

    class CountResult{
        public String theme;
        public String sentiment;
        public String total;
    }
}

public class SentimentsRepositoryImpl implements CustomSentimentsRepository {
    private final MongoTemplate mongoTemplate;


    @Autowired
    public SentimentsRepositoryImpl(MongoTemplate mongoTemplate) {

        this.mongoTemplate = mongoTemplate;
    }

    @Override
    public List<CountResult> myCountGroupByThemeAndSentiment(){
        Aggregation agg = Aggregation.newAggregation(
                Aggregation.group("theme","sentiment").count().as("total"),
                Aggregation.project("theme","sentiment").andInclude("total"),


        Aggregation.sort(Sort.Direction.ASC,"theme","sentiment")
    );


    AggregationResults<CountResult> groupResults
            = mongoTemplate.aggregate(agg,"sentiments",  CountResult.class);


        return groupResults.getMappedResults();
    }
}

@RepositoryRestResource(collectionResourceRel = "sentiments", path = "sentiments")
public interface SentimentsRepository extends CrudRepository<Sentiments, String>, CustomSentimentsRepository {
    //Other methods

}

@RestController
@RequestMapping(value = "sentiments/search")
public class ChartsController {
    @Autowired
    private SentimentsRepository sentimentsRepository;

    @RequestMapping(value = "myCountGroupByThemeAndSentiment", method = RequestMethod.GET)
    public ResponseEntity<?> yourCustomMethod() {
        List<?> count=sentimentsRepository.myCountGroupByThemeAndSentiment();
        return new ResponseEntity(count, HttpStatus.OK);
    }

}

Answer 3

您可以使用 spring data mongodb 2.2.X 版本中可用的@Aggrgation：

@Aggregation(pipeline = {"{ '$group': { '_id' : '$lastname', names : { $addToSet : '$?0' } } }", "{ '$sort' : { 'lastname' : -1 } }"}) List<PersonAggregate> groupByLastnameAnd(String property);