Question

我有2个收藏集。

案例

_id: ObjectId.
name: string.
info: {
    [here can be many different fields with diff types]
    entities: [
        { role: string;
          id: ObjectId;
        } <--- here can be a lot of entities
    ]
}

实体

_id: ObjectId.
type: string,
name: string,
info: {
    [here can be many different fields with diff types]
}

我需要检索所有案例，并且对于每个case.info.entities对象，我需要具有字段 data ，该字段等于实体文档（case.info.entities.id === entity_id）

示例我需要的东西

_id: ObjectId.
name: string.
info: {
    [here can be many different fields with diff types]
    entities: [
        { role: string;
          id: ObjectId;
          data: {
            _id: ObjectId.
            type: string,
            name: string,
            info: {
              [here can be many different fields with diff types]
            }
          }
        } <--- here can be a lot of entities
    ]
}

如何正确执行操作？

Answer 1

您几乎完成了所有操作。根据您的查询和模型，我在下面给出了查询（字段名称可能不同）。希望对您有所帮助。

db.cases.aggregate([
{ $unwind: '$info.relatedEntities' },
{ $lookup: {
        from: 'entities',
        localField: 'info.relatedEntities.entity',
        foreignField: '_id',
        as: 'info.relatedEntities.entityObject'
    }
},
{ $group: {
    _id: {
        _id : '$_id',
        templateType : '$templateType',
        name : '$name',
        info :  {
            address : "$info.address",
        }
    },
    'relatedEntities': {
        $push: {
             role : '$info.relatedEntities.role',
             entity : '$info.relatedEntities.entity',
             data : { $arrayElemAt: [ '$info.relatedEntities.entityObject', 0 ] }
        }
    }
  }
},
{
  $project : {
     _id : '$_id._id',
     name : '$_id.name',
     templateType : '$_id.templateType',
     info : {
        address : '$_id.info.address',
        entities : '$relatedEntities'
     }
    }
  }
]).pretty()

MongoDB $ lookup与带有嵌套数组的嵌套对象

1 个答案: