[NodeJS] Mongoose ref关联删除数据

环境

• Node: v7.0.0
• Bluebird: v3.4.6
• Mongoose: v4.6.8

参考文档

ECMAScript 6 入门 —— Promise对象, 阮一峰
Mongoose 之 Population 使用, aikin
Mongoose API v4.7.2

语句

Model.update(conditions, {$pull: {field: value}}, [options], [callback])

若想要同时更新多个匹配的User，则要在 [option] 处添加参数，{multi: true}。

Model.update 的具体使用方法详见Mongoose 帮助文档。

样例

Model

存放在了 model.js 中。

var mongoose = require('mongoose');
mongoose.Promise = require('bluebird');

var Schema = mongoose.Schema;
var userSchema = new Schema({
  name: String,
  age: Number,
  posts: [{type: Schema.Types.ObjectId, ref: 'post'}],
  comments: [{type: Schema.Types.ObjectId, ref: 'comment'}]
});
var User = mongoose.model('user', userSchema);

var postSchema = new Schema({
  title: String,
  content: String,
  author: {type: Schema.Types.ObjectId, ref: 'user'},
  comments: [{type: Schema.Types.ObjectId, ref: 'comment'}]
});
var Post = mongoose.model('post', postSchema);

var commentSchema = new Schema({
  content: String,
  author: {type: Schema.Types.ObjectId, ref: 'user'}
})
var Comment = mongoose.model('comment', commentSchema);

exports.User = User;
exports.Post = Post;
exports.Comment = Comment;

上面的 Model 实现了，User->Post，User->Comment；Post->User，Post->Comment；Comment->User的关联。

存储测试数据

var User = require('./model').User;
var Post = require('./model').Post;
var Comment = require('./model').Comment;
var Promise = require('bluebird');

var user_tom = new User({name: 'Tom', age: 19});
var user_jerry = new User({name: 'Jerry', age: 22});
var user_david = new User({name: 'David', age: 15});
var post_test = new Post({title: 'test', content: 'wakaka'});
var comment_walala = new Comment({content: 'walala'});

Promise.all([user_tom.save(), user_jerry.save(), user_david.save()])
.spread(function(utom, ujerry, udavid) {
  post_test.author = utom;
  comment_walala.author = utom;
  return Promise.all([post_test.save(), comment_walala.save(), utom, udavid]);
}).spread(function(post, comment, utom, udavid) {
  utom.posts.push(post);
  utom.comments.push(comment);
  udavid.comments.push(comment);
  post.comments.push(comment);
  return Promise.all([utom.save(), post.save(), udavid.save()]);
}).spread(function() {
  console.log('success');
}).catch(function(reason) {
  console.log(reason);
});

这里创建了 3 个 User，1 个 Post， 1 个 Comment。user_Tom 和 user_david 的 comments 关联到 comment_walala；comment_walala 和 post_test 的 author 关联到 user_Tom； post_test 的 comments 关联到 comment_walala。

用 mongo 连接到 mongodb 查看一下。

> db.users.find().pretty()
{
    "_id" : ObjectId("584baa387378d64d6e8a9fd6"),
    "name" : "Tom",
    "age" : 19,
    "comments" : [
        ObjectId("584baa387378d64d6e8a9fda")
    ],
    "posts" : [
        ObjectId("584baa387378d64d6e8a9fd9")
    ],
    "__v" : 1
}
{
    "_id" : ObjectId("584baa387378d64d6e8a9fd7"),
    "name" : "Jerry",
    "age" : 22,
    "comments" : [ ],
    "posts" : [ ],
    "__v" : 0
}
{
    "_id" : ObjectId("584baa387378d64d6e8a9fd8"),
    "name" : "David",
    "age" : 15,
    "comments" : [
        ObjectId("584baa387378d64d6e8a9fda")
    ],
    "posts" : [ ],
    "__v" : 1
}
> db.posts.find().pretty()
{
    "_id" : ObjectId("584baa387378d64d6e8a9fd9"),
    "author" : ObjectId("584baa387378d64d6e8a9fd6"),
    "title" : "test",
    "content" : "wakaka",
    "comments" : [
        ObjectId("584baa387378d64d6e8a9fda")
    ],
    "__v" : 1
}
> db.comments.find().pretty()
{
    "_id" : ObjectId("584baa387378d64d6e8a9fda"),
    "author" : ObjectId("584baa387378d64d6e8a9fd6"),
    "content" : "walala",
    "__v" : 0
}

图示

删除和查询结果

代码

var User = require('./model').User;
var Post = require('./model').Post;
var Comment = require('./model').Comment;
var Promise = require('bluebird');

Comment.findOne({content: 'walala'}).then(function(comment) {
  return User.update({comments: {$in: [comment._id]}}, {$pull: {'comments': comment._id}}, {multi: true}).exec();
}).then(function(res) {
  console.log(res);
});

因为加了 {multi: true}，所以会同时更新所有匹配到的User。

返回值

{ ok: 1, nModified: 2, n: 2 }

表示成功，修改了 2 个。

在查询一下数据库。

> db.users.find().pretty()
{
    "_id" : ObjectId("584baa387378d64d6e8a9fd6"),
    "name" : "Tom",
    "age" : 19,
    "comments" : [ ],
    "posts" : [
        ObjectId("584baa387378d64d6e8a9fd9")
    ],
    "__v" : 1
}
{
    "_id" : ObjectId("584baa387378d64d6e8a9fd7"),
    "name" : "Jerry",
    "age" : 22,
    "comments" : [ ],
    "posts" : [ ],
    "__v" : 0
}
{
    "_id" : ObjectId("584baa387378d64d6e8a9fd8"),
    "name" : "David",
    "age" : 15,
    "comments" : [ ],
    "posts" : [ ],
    "__v" : 1
}

Tom 和 David 的comments内容已经没了。

以上所有，如有错误，麻烦指出，我会及时更改的。