Spring Boot Mongo DB 查找聚合操作

Question

首先我想说的是我刚接触 MongoDB，尤其是 MongoData with Springs。我有以下收藏

类别

@Data
@Document(collection = "categories")
public class Category {
    @Id
    private ObjectId id;
    @CreatedBy
    private ObjectId creatorId;
    @CreatedDate
    private LocalDateTime createdAt;
    @LastModifiedDate
    private LocalDateTime modifiedAt;
    @LastModifiedBy
    private ObjectId modifiedBy;
    private String title;
    private String notes;
    private boolean enabled = true;
}

活动

@Data
@Document(collection = "activities")
public class Activity {

    @Id
    private ObjectId id;
    @CreatedBy
    private ObjectId creatorId;
    @CreatedDate
    private LocalDateTime createdAt;
    @LastModifiedDate
    private LocalDateTime modifiedAt;
    @LastModifiedBy
    private ObjectId modifiedBy;

    private ObjectId budgetId;
    private ObjectId categoryId;
    private String title;
    private String notes;
    private Double estimatedBudget;
    private boolean enabled;
    private boolean recurring;
}

我想出了一个简单的查询，它将两个集合连接起来，这符合我的预期，如下所示（......也可能不是超级酷的查询）。这个想法是我想根据 categoryId 将所有活动分组在 Category 内。然后，我只想检索具有给定budgetId 的活动。 我应该能够检索所有类别，无论其中是否存在活动，例如 SQL 中的 LEFT JOIN

db.categories.aggregate([
{

$lookup: {
        from: "activities",
        localField : "_id",
        foreignField: "categoryId",
        pipeline: [
              {$match: { $and:[{"budgetId": ObjectId("60f8ef1ed7056b730cdce1db") }] }}
        ],
        as: "activities"
    },
},
 {
        $match: {
            $and:[{"enabled": true}]
            }
        }

])

这以某种方式起作用。 那么问题是如何将上述查询转换为 Springs 中的 AggregationOperation？

我有以下内容，但它排除了其中没有活动的类别。

  List<AggregationOperation> operations = new ArrayList<>();


        Criteria criteria = Criteria.where("enabled").is(true);

        operations.add(match(criteria));


        Criteria forBudgetActivitiesCriteria =  Criteria.where("activities.budgetId").is(budgetId);


        operations.add(lookup("activities", "_id", "categoryId", "activities"));
        operations.add(match(forBudgetActivitiesCriteria));

        TypedAggregation<Category> aggregation = newAggregation(Category.class, operations);
        AggregationResults<Category> results = mongoTemplate.aggregate(aggregation, Category.class);

我猜问题出在这里

Criteria.where("activities.budgetId").is(budgetId);

帮助。并提前致谢。

Answer 1

聚合是

db.categories.aggregate([
  {
    $lookup: {
      from: "activities",
      let: { "cId": "$_id" },
      pipeline: [
        {
          $match: {
            $expr: {
              $and: [
                { $eq: [ "$budgetId", "abc" ] },
                { $eq: [ "$$cId", "$categoryId" ] },
                { $eq: [ "$enabled", true ] }
              ]
            }
          }
        }
      ],
      as: "join_activities"
    },
    
  }
])

工作Mongo playground

mongodb中有两个$lookups。一种是spring数据支持的标准查找（LookupOperation类），第二种是相关子查询查找。不幸的是弹簧数据不支持它。但是有一个Trick to convert

我们可以把它写成 Bson 对象

@Autowired
private MongoTemplate mongoTemplate;

public List<YOUR_CONVERTER_CLASS> test(String value) {

    Aggregation aggregation = Aggregation.newAggregation(
        l-> new Document("$lookup",
                new Document("from","activities")
                .append("let",new Document("cId","$_id"))
                .append("pipeline",
                    Arrays.asList(
                        new Document("$match",
                            new Document("$expr",
                                new Document(
                                    "$and",
                                    Arrays.asList(
                                        new Document("$eq",Arrays.asList("$budgetId","abc"))
                                        .append("$eq",Arrays.asList("$$cId","$categoryId"))
                                        .append("$eq",Arrays.asList("$enabled",true))
                                    )
                                )
                            )
                        )
                    )
                ).append("as","join_activities")
        )
    ).withOptions(AggregationOptions.builder().allowDiskUse(Boolean.TRUE).build());

    return mongoTemplate.aggregate(aggregation, mongoTemplate.getCollectionName(YOUR_COLLECTION_CLASS.class), YOUR_CONVERTER_CLASS.class).getMappedResults();

}

注意：这未经测试，而是基于工作的 mongo 游乐场编写的。 Mongodb 5.0 与您在帖子中发布的签名相同。如果你需要转换你的查询，你可以使用技巧和转换，它只是一个键值对