Question

我正在尝试通过其ID进行构建：

我有一个名为buildings的收藏集：

{
    "_id" : ObjectId("5b3b1cc79c23061e4d4634e4"),
    "buildings" : [ 
        {
            "id" : 0,
            "name" : "Farm",
            "description" : "Best farm of all times",
            "img" : "http://i.hizliresim.com/yq5g57.png",
            "wood" : "50",
            "stone" : "10"
        }, 
        {
            "id" : 1,
            "name" : "Storage",
            "description" : "Store your resources.",
            "img" : "http://i.hizliresim.com/yq5g47.png",
            "wood" : "100",
            "stone" : "200"
        }
    ]
}

例如ID为0的数字，我想获取Farm的数据。

我尝试了这个： db.getCollection（'buildings'）。find（{“ buildings.id”：0}）

不起作用

示例输出：

{
                "id" : 0,
                "name" : "Farm",
                "description" : "Best farm of all times",
                "img" : "http://i.hizliresim.com/yq5g57.png",
                "wood" : "50",
                "stone" : "10"
            }

尝试：

var data = Buildings.find({},{buildings:{$elemMatch:{id:0}}}).fetch();
console.log(JSON.stringify(data));

结果：（所有数据）

[{"_id":{"_str":"5b3b1cc79c23061e4d4634e4"},"buildings":[{"id":0,"name":"Farm","description":"Best farm of all times","img":"http://i.hizliresim.com/yq5g57.png","wood":"50","stone":"10"},{"id":1,"name":"Storage","description":"Store your resources.","img":"http://i.hizliresim.com/yq5g47.png","wood":"100","stone":"200"}]}]

Answer 1

您可以使用$filter聚合从数组中排除不需要的元素

db.collection.aggregate([
  { "$match": { "buildings.id": 0 }},
  { "$project": {
    "shapes": {
      "$arrayElemAt": [
        { "$filter": {
          "input": "$buildings",
          "as": "building",
          "cond": {
            "$eq": [
              "$$building.id",
              0
            ]
          }
        }},
        0
      ]
    },
    "_id": 0
  }}
])

Answer 2

为此尝试

db.getCollection("collectionName").find({buildings: {"$elemMatch": {"id" : "0"}}})

在这里，find方法将查找（光标）具有建筑物和id = 0的数据

Answer 3

db.collection.find({
    buildings: {
        $elemMatch: {
            id: 0
        }
    }
}, {
    'buildings.$': 1
})

查询属性数组mongodb

3 个答案: