node.js Mongoose - 查询以从多个集合中获取数据
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Mongoose - query to get data from multiple collections
提问by laxman
I want to get query of the mongoosein nodejs application as describe below out put.
user.js, comment.js and post.js are the model files I used.
我想在 nodejs 应用程序中查询猫鼬，如下所述。
user.js、comment.js 和 post.js 是我使用的模型文件。
user.js
用户.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
评论.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
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'});
wants to get out put as follows:
想出去如下：
{
"nick_name":"prakash",
"email":"[email protected]",
"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,
},
]
}
dependencies
依赖
"express" => "version": "4.7.4",
"mongoose" => "version": "4.4.5",
"mongodb" => "version": "2.4.9",
"OS" => "ubuntu 14.04 lts 32bit",
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.
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。
回答by PigBoT
There are no 'joins' in Mongo. But what you would do is change your User Schema to store the ObjectId's of the Comment and Post documents in an array of your User. Then use 'populate' when you need the data with the user.
Mongo 中没有“连接”。但是您要做的是更改您的用户架构以将 Comment 和 Post 文档的 ObjectId 存储在您的用户数组中。然后在需要用户的数据时使用“填充”。
const userSchema = new Schema({
nick_name:{type:String},
email: {
type: String,
trim: true,
required: '{PATH} is required!',
index: true,
},
comments: [{ type: Schema.Types.ObjectId, ref:'Comment' }],
posts: [{ type: Schema.Types.ObjectId, ref:'Post' }]
}, {timestamps: true});
mongoose.model('User', userSchema);
Your query would then look something like this:
您的查询将如下所示：
User.find()
.populate('comments posts') // multiple path names in one requires mongoose >= 3.6
.exec(function(err, usersDocuments) {
// handle err
// usersDocuments formatted as desired
});
回答by Muthuramalingam Duraipandi
It is possible .you should use aggregation. it should work. Initiate the variable
这是可能的。你应该使用聚合。它应该工作。 启动变量
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
});
回答by fuelusumar
Of course it is possible, you just have to use populate, let me tell you how:
当然可以，你只需要使用populate，让我告诉你如何：
Import your schemas
导入您的架构
var mongoose = require('mongoose');
var userSch = require('userSchema');
var postSch = require('postSchema');
var commSch = require('commentSchema');
Init all the necessary vars
初始化所有必要的变量
var userModel = mongoose.model('User', userSch);
var postModel = mongoose.model('Post', postSch);
var commModel = mongoose.model('Comment', commSch);
And now, do the query
现在，做查询
postModel.find({}).populate('User')
.exec(function (error, result) {
return callback(null, null);
});
commModel.find({}).populate('User')
.exec(function (error, result) {
return callback(null, null);
});
This way you get the user inside of your comment and your post, to get the post and comments inside of your user, you have to do 3 queries, one for the user, one for the comments and one for the post, and mix all together
通过这种方式，您可以让用户进入您的评论和帖子，要获取用户内部的帖子和评论，您必须进行 3 个查询，一个针对用户，一个针对评论，一个针对帖子，然后混合所有一起
