Question

我有这个猫鼬模型：

var mySubEntitySchema = new Schema({
  property1: String,
  property2: String
});

var myEntitySchema = new Schema({
  name: String,
  sub: [mySubEntitySchema]
});

export var MyEntityModel: mongoose.Model<MyEntityDocument> = mongoose.model<MyEntityDocument>("MyEntity", myEntitySchema);

现在我想得到一个特定的MyEntityDocument，我有_id，但只有subDocuments匹配property1 =＆＃34;示例＆＃34;。

有没有办法做到这一点？

我尝试使用Aggregate的解决方案，但没有任何成功：

MyEntityModel.aggregate([
{$match: { "_id": myId, "sub.property1":"example" }},
      {$unwind: "$sub"},
      {$match: { "sub.property1":"example"}},
      {$group: {"_id":"$_id","subs":{$push:"$sub"}}}
    ], (error, result) => {
        console.log("Result = " + JSON.stringify(result));
      }
    });

但它什么也没有回报。如果我没有在第一个$ match子句中放置＆＃34; _id＆＃34;：myId，那么我会得到结果，但我只想要一个与我所拥有的_id相对应的结果。

任何人都知道我该怎么做？

编辑：如上所述，这是一个例子。

有了这些数据：

  {
    "_id": "54c12276fcb2488d300795e4",
    "name": "a",
    "sub": [
      {
        "_id": "54c12276fcb2488d300795e0",
        "property1": "example",
        "property2": "something"
      },
      {
        "_id": "54c12276fcb2488d300795e1",
        "property1": "notmuch",
        "property2": "somethingelse"
      },
      {
        "_id": "54c12276fcb2488d300795e2",
        "property1": "notinteresting",
        "property2": "something"
      },
      {
        "_id": "54c12276fcb2488d300795e3",
        "property1": "example",
        "property2": "anotherthing"
      }
    ]
  },
  {
    "_id": "54c12277fcb2488d300795e5",
    "name": "b",
    "sub": [
      {
        "_id": "54c12276fcb2488d300795e6",
        "property1": "example",
        "property2": "word"
      }
    ]
  }

我希望实体使用_id＆＃34; 54c12276fcb2488d300795e4＆＃34;和匹配property1 =＆＃34的子磁盘;示例＆＃34;。所以预期的结果是：

  {
    "_id": "54c12276fcb2488d300795e4",
    "name": "a",
    "sub": [
      {
        "_id": "54c12276fcb2488d300795e0",
        "property1": "example",
        "property2": "something"
      },
      {
        "_id": "54c12276fcb2488d300795e3",
        "property1": "example",
        "property2": "anotherthing"
      }
    ]
  }

Answer 1

您可以使用findOne来检索您想要的内容。

MyEntityModel.findOne({_id : myId , "sub.property1" :"example"},{'sub.$' : 1},function(err,result){
    if(!err)
    {
        if(result)
        {
            //result is the document you were searching for
        }
    }
});

{'sub。$'：1}将只返回匹配的元素。

浏览mongoose query documentation以便更好地理解。

Answer 2

您的查询似乎正常工作并且正如预期的那样得到结果，但聚合函数的语法不正确。请参阅this链接，了解如何使用mongoose编写聚合查询。您不应该像在mongodb console中那样传递数组。只需传递逗号分隔的查询，如下面的查询所示。

MyEntityModel.aggregate(
  {$match: { "_id": myId, "sub.property1":"example" }},
  {$unwind: "$sub"},
  {$match: { "sub.property1":"example"}},
  {$group: {"_id":"$_id","name": {"$first": "$name"}, "subs":{$push:"$sub"}}}
, (error, result) => {
    console.log("Result = " + JSON.stringify(result));
  }
});

获取仅包含与mongoose标准匹配的子文档的文档

2 个答案: