将数据从一个模型分为两个模型后，如何重写猫鼬查询? [英] how can I rewrite my mongoose query after splitting data from one model into two?

问题描述

在我的应用程序中，我存储评论.以前，我的模型如下所示:

In my application I store comments. Previously my model for that looked like this:

var CommentsSchema = new Schema({
    username: {type: String},
    display_name: {type: String},
    facebook_username: {type: String},
    text_content: {type: String},
    photo_content_url: {type: String},
    hashtags: {type: [String]},
    device_id: {type: String},
    comment_date: {type: Date, default: Date.now},
    friends_only: {type: Boolean, default: false}
}

每个评论-除了存储其详细信息之外-还包含有关作者的详细信息，例如从中添加注释的username，facebook_username，device_id和display_name.还有一个bool标志friends_only，根据该标志，我决定是只对用户的Facebook朋友还是所有人都可见该评论.

Each comment - besides storing its details - had also details about the author, e.g. username, facebook_username, device_id from which the comment was added and display_name. There was also a bool flag friends_only based on which I was deciding whether that comment should be visible only to user's facebook friends or to everyone.

用于提取所有注释的node.js/mongoose查询的构造如下:

Construction of the node.js/mongoose query for fetching all comments looked like this:

commentsRoutes.post('/friends', function (req, res) {
    var friends = req.body.friends;
    var publicComments = req.body.publicComments;

    var hashtagsInput = req.body.hashtags;

    var startDate = req.body.startDate;
    var endDate = req.body.endDate;

    var query= {};
    query.$and = [];

    // and condition on start date
    if(startDate != undefined) {
        var startDate = new Date(req.param('startDate'));
        var endDate = new Date(req.param('endDate'));
        query.$and.push({"comment_date":{$gte: startDate}});
        query.$and.push({"comment_date":{$lte: endDate}});
    }

    // and condition on hastags
    if (hashtagsInput != undefined) {
        var hashtags = hashtagsInput.split(",");
        query.$and.push({"hashtags":{$in: hashtags}});
    }

    // creating a OR condition for facebook friends and public flag
    var friend_query = {};
    friend_query.$or = [];

    if (friends != undefined) {
        var friendsSplit = friends.split(",");
        friend_query.$or.push({"facebook_username":{$in: friendsSplit}});
    }

    if (publicComments != undefined && publicComments === "true") {
        friend_query.$or.push({friends_only: false});
    }

    //Merging facebook friend condition with other condition with AND operator.
    query.$and.push(friend_query);

    var finalQuery = Comment.find(query)

使用上面的代码，用户可以获取其朋友发布的内容(设置为公开或私有)以及所有其他公开内容(来自其他所有人).

With the code above user could fetch content posted by his friends (that was set either to public or private) and all other public content (from everyone else).

我已决定更改所有内容，并将数据分为两个模型.更改后，我有:

I've decided to change all of that and split the data into two models. After changing it I have:

var CommentsSchema = new Schema({
    user_id: {type: String, required: true, ref: 'users' },
    text_content: {type: String},
    photo_content_url: {type: String},
    hashtags: {type: [String]},
    comment_date: {type: Date, default: Date.now},
    friends_only: {type: Boolean, default: false},
    device_id: {type: String}
}

和

var UsersSchema = new Schema({
    username: {type: String},
    facebook_username: {type: String},
    display_name: {type: String}
}

现在，当我想保留旧功能时，需要修改负责创建查询的代码. 我可以将两个查询与async合并，或者另一种方法是使用mongoose .populate选项.我决定采用第二种选择，因此现在我需要将负责创建or查询的代码移到populate函数的match部分:

Now, when I want to keep the old functionality, I need to modify the code responsible for creating the query. I could merge two queries with async, or the other way is to use mongoose .populate option. I decided to go with the second choice, so now I need to move the code responsible for creating or query to the match part of populate function:

...
var finalQuery = Comment.find(query)

finalQuery.populate({path: 'user_id', 
    select: 'facebook_username display_name username',
    match: {

}});

我不知道该怎么做.你能帮我吗?

I don't know how to do it. Can you help me with that?

推荐答案

首先，我建议您使用填充查询，如果您认为填充不会提供所需的数据，则可以运行两个查询并合并这些结果.

First, i suggest you that go with a populate query, if you feel that populate won't give you a data that you need that you can run two queries and merge those results.

对于填充，我从猫鼬的官方文档中找到了解决方案.你可以这样

for populate, i found the solution from the official doc of mongoose. you can do like this.

var mongoose = require('mongoose')
  , Schema = mongoose.Schema

var personSchema = Schema({
  _id     : Number,
  name    : String,
  age     : Number,
  stories : [{ type: Schema.Types.ObjectId, ref: 'Story' }]
});

var storySchema = Schema({
  _creator : { type: Number, ref: 'Person' },
  title    : String,
  fans     : [{ type: Number, ref: 'Person' }]
});

var Story  = mongoose.model('Story', storySchema);
var Person = mongoose.model('Person', personSchema);

Story
.findOne({ title: 'Once upon a timex.' })
.populate('_creator')
.exec(function (err, story) {
  if (err) return handleError(err);
  console.log('The creator is %s', story._creator.name);
  // prints "The creator is Aaron"
});

这是文档链接: http://mongoosejs.com/docs/populate.html

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