Node.js Mongoose查询：如何查找对象数组

如果您以以下格式发送json数据，服务器将尝试遍历mongodb的item文档，并编写代码，返回具有相同用户ID的数据以及itemTag接收到的完全相同的json数据

我有这个模式：

var subSchema = mongoose.Schema({
  main:Number,
  sub:Number,
  color:Number
},{ _id : false });

var ItemSchema = new Schema({
    userId:String,
    date:String,
    itemTag: [subSchema]
}, { versionKey: false });

{ 
   "_id" : ObjectId("58ba81eea341c37ed7268703"),
   "date" : "20170304_175923", 
   "userId" : "aaa", 
   "itemTag" : [ 
       { 
           "main" : 3, 
           "sub" : 7,  
           "color" : 1
       }, { 
           "main" : 3, 
           "sub" : 1,  
           "color" : 11
       }, { 
           "main" : 4, 
           "sub" : 4,  
           "color" : 1
       }, {
           "main" : 5, 
           "sub" : 2,  
           "color" : 1
       } 
    ] 
},
{ 
   "_id" : ObjectId("58ba81eea341c37ed7268723"),
   "date" : "20170305_125923", 
   "userId" : "aaa", 
   "itemTag" : [ 
       { 
           "main" : 3, 
           "sub" : 7,  
           "color" : 1

       }, { 
           "main" : 2, 
           "sub" : 2,
           "color" : 2
       } 
    ] 
}

{ 
   "_id" : ObjectId("58ba81eea341c37ed7268703"),
   "date" : "20170304_175923", 
   "userId" : "aaa", 
   "itemTag" : [ 
       { 
           "main" : 3, 
           "sub" : 7,  
           "color" : 1
       }, { 
           "main" : 3, 
           "sub" : 1,  
           "color" : 11
       }, { 
           "main" : 4, 
           "sub" : 4,  
           "color" : 1
       }, {
           "main" : 5, 
           "sub" : 2,  
           "color" : 1
       } 
    ] 
}

---

db数据：

var subSchema = mongoose.Schema({
  main:Number,
  sub:Number,
  color:Number
},{ _id : false });

var ItemSchema = new Schema({
    userId:String,
    date:String,
    itemTag: [subSchema]
}, { versionKey: false });

{ 
   "_id" : ObjectId("58ba81eea341c37ed7268703"),
   "date" : "20170304_175923", 
   "userId" : "aaa", 
   "itemTag" : [ 
       { 
           "main" : 3, 
           "sub" : 7,  
           "color" : 1
       }, { 
           "main" : 3, 
           "sub" : 1,  
           "color" : 11
       }, { 
           "main" : 4, 
           "sub" : 4,  
           "color" : 1
       }, {
           "main" : 5, 
           "sub" : 2,  
           "color" : 1
       } 
    ] 
},
{ 
   "_id" : ObjectId("58ba81eea341c37ed7268723"),
   "date" : "20170305_125923", 
   "userId" : "aaa", 
   "itemTag" : [ 
       { 
           "main" : 3, 
           "sub" : 7,  
           "color" : 1

       }, { 
           "main" : 2, 
           "sub" : 2,
           "color" : 2
       } 
    ] 
}

{ 
   "_id" : ObjectId("58ba81eea341c37ed7268703"),
   "date" : "20170304_175923", 
   "userId" : "aaa", 
   "itemTag" : [ 
       { 
           "main" : 3, 
           "sub" : 7,  
           "color" : 1
       }, { 
           "main" : 3, 
           "sub" : 1,  
           "color" : 11
       }, { 
           "main" : 4, 
           "sub" : 4,  
           "color" : 1
       }, {
           "main" : 5, 
           "sub" : 2,  
           "color" : 1
       } 
    ] 
}

**和客户端发送json数据：** 服务器获取 req.body.userId req.body.itemTag

{ 
    "userId":"aaa",
    "itemTag":[{
        "main":3,
        "sub":7,
        "color":1
    },{
        "main":4,
        "sub":4,
        "color":1
    }]
}

我想得到：

var subSchema = mongoose.Schema({
  main:Number,
  sub:Number,
  color:Number
},{ _id : false });

var ItemSchema = new Schema({
    userId:String,
    date:String,
    itemTag: [subSchema]
}, { versionKey: false });

{ 
   "_id" : ObjectId("58ba81eea341c37ed7268703"),
   "date" : "20170304_175923", 
   "userId" : "aaa", 
   "itemTag" : [ 
       { 
           "main" : 3, 
           "sub" : 7,  
           "color" : 1
       }, { 
           "main" : 3, 
           "sub" : 1,  
           "color" : 11
       }, { 
           "main" : 4, 
           "sub" : 4,  
           "color" : 1
       }, {
           "main" : 5, 
           "sub" : 2,  
           "color" : 1
       } 
    ] 
},
{ 
   "_id" : ObjectId("58ba81eea341c37ed7268723"),
   "date" : "20170305_125923", 
   "userId" : "aaa", 
   "itemTag" : [ 
       { 
           "main" : 3, 
           "sub" : 7,  
           "color" : 1

       }, { 
           "main" : 2, 
           "sub" : 2,
           "color" : 2
       } 
    ] 
}

{ 
   "_id" : ObjectId("58ba81eea341c37ed7268703"),
   "date" : "20170304_175923", 
   "userId" : "aaa", 
   "itemTag" : [ 
       { 
           "main" : 3, 
           "sub" : 7,  
           "color" : 1
       }, { 
           "main" : 3, 
           "sub" : 1,  
           "color" : 11
       }, { 
           "main" : 4, 
           "sub" : 4,  
           "color" : 1
       }, {
           "main" : 5, 
           "sub" : 2,  
           "color" : 1
       } 
    ] 
}

---

我不确定，但您应该使用：

itemTag.$.main

语法

要获取阵列中的第一项，可以使用：

itemTag.$0.main

对于数组中的第二项：

itemTag.$1.main

等等……

试试这个

   db.collection.find(
        {"userId" : req.body.userId,"itemTag.main" : req.body.itemTag},
        {itemTag : 1,userId:1})
        .sort(sortQuery)
        .skip(skipPage)
        .limit(16)

或

3）-如果要从数组中获取特定元素

db.collection.find(
  {"userId" : req.body.userId,"itemTag":{ "$elemMatch" : {main : req.body.itemTag}}},
     {"itemTag.$.main"  : 1,userId:1})
     .sort(sortQuery)
    .skip(skipPage)
    .limit(16)

---

您可以尝试下面的“查找查询”。当数组中的每个值都有条目时，查询使用

$all

和

$elemMatch

返回行

var rItemTag = req.body.itemTag
var qItemTag = rItemTag.map(value => ({"elemMatch": value}));
db.collection.find({itemTag: {$all: qItemTag}})

---

我不明白您想要实现什么，您能再解释一下吗？我想在db中找到与以下itemTag数组相同的值。{“ItemTag”：[{“Main”：3，“Sub”：7，“Color”：1}，{“Main”：3，“Sub”：1，“Color”：11}}}谢谢。。但我收到了这样一条消息：{“消息”：“转换为数字失败，因为值\”[{main:3，sub:7，color:1}，{main:4，sub:4，color:1}]\“路径\“main\”对于模型\“Item\”，“name”：“CastError”，“stringValue”：“\”[{main:3，sub:7，color:1}，{main:4，sub:4，color:1}]，“种类”：“数字”，请发布您正在执行的查询，并确保所有文档字段（“主”、“子”和“颜色”都是数字字段）