Mongoose - 查询以从多个集合中获取数据 [英] Mongoose - query to get data from multiple collections
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问题描述
我想在 nodejs 应用程序中获取猫鼬的查询,如下所述.
user.js、comment.js 和 post.js 是我使用的模型文件.
I want to get query of the mongoose in nodejs application as describe below out put.
user.js, comment.js and post.js are the model files I used.
user.js
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var ObjectId = Schema.ObjectId;
var userSchema = new Schema({
nick_name:{type:String},
email: {
type: String,
trim: true,
required: '{PATH} is required!',
index: true,
},
},{ collection: 'user'});
var User = mongoose.model('User', userSchema);
module.exports = User;
comment.js
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var ObjectId = Schema.ObjectId;
var commentSchema = new Schema({
comment: type:String,
user_id:{
type:Schema.Types.ObjectId, ref:'User'
},
is_active :1
},{ collection: 'comment'});
post.js
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var ObjectId = Schema.ObjectId;
var postSchema = new Schema({
post: type:String,
user_id:{
type:Schema.Types.ObjectId, ref:'User'
},
is_active :1
},{ collection: 'post'});
想出去如下:
{
"nick_name":"prakash",
"email":"prakash@mailinator.com",
"comments":[
{
"comment":"this is a comment text1",
"is_active":1,
},
{
"comment":"this is a comment text2",
"is_active":1,
}
],
"posts":[
{
"post":"this is a post text1",
"is_active":1,
},
{
"post":"this is a post text2",
"is_active":1,
},
{
"post":"this is a post text3",
"is_active":1,
},
]
}
依赖项
"express" => "version": "4.7.4",
"mongoose" => "version": "4.4.5",
"mongodb" => "version": "2.4.9",
"OS" => "ubuntu 14.04 lts 32bit",
如果无法查询,请建议我一个合适的猫鼬插件.但我不想对 user.js 文件及其 userSchema 对象进行任何更改.
if query is not possible ,please suggests me a proper mongoose plugn. but I don't want to any changes in user.js file and its userSchema object.
推荐答案
有可能.你应该使用聚合.它应该工作.初始化变量
It is possible .you should use aggregation. it should work. Initiate the variable
var mongoose = require('mongoose');
var userCollection = require('./user');//import user model file
var resources = {
nick_name: "$nick_name",
email: "$email"};
userCollection.aggregate([{
$group: resources
}, {
$lookup: {
from: "Comments", // collection to join
localField: "_id",//field from the input documents
foreignField: "user_id",//field from the documents of the "from" collection
as: "comments"// output array field
}
}, {
$lookup: {
from: "Post", // from collection name
localField: "_id",
foreignField: "user_id",
as: "posts"
}
}],function (error, data) {
return res.json(data);
//handle error case also
});
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