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mongoose-population
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var ObjectId = mongoose.Types.ObjectId;
console.log('Running mongoose version %s', mongoose.version);
var UserSchema = new Schema({
name : String,
posts : [{
type : Schema.Types.ObjectId,
ref : 'Post'
}]
});
var User = mongoose.model('User', UserSchema);
var PostSchema = new Schema({
poster: {
type : Schema.Types.ObjectId,
ref : 'User'
},
comments: [{
type : Schema.Types.ObjectId,
ref : 'Comment'
}],
title: String
});
var Post = mongoose.model('Post', PostSchema);
var CommentSchema = new Schema({
post: {
type : Schema.Types.ObjectId,
ref : "Post"
},
commenter: {
type : Schema.Types.ObjectId,
ref : 'User'
},
content: String
});
var Comment = mongoose.model('Comment', CommentSchema);
mongoose.connect('mongodb://localhost/population-test', function (err) {
// if we failed to connect, abort
if (err) throw err;
// we connected ok
createData();
});
function createData() {
var userIds = [new ObjectId, new ObjectId, new ObjectId];
var postIds = [new ObjectId, new ObjectId, new ObjectId];
var commentIds = [new ObjectId, new ObjectId, new ObjectId];
var users = [];
var posts = [];
var comments = [];
users.push({
_id : userIds[0],
name : 'aikin',
posts : [postIds[0]]
});
users.push({
_id : userIds[1],
name : 'luna',
posts : [postIds[1]]
});
users.push({
_id : userIds[2],
name : 'luajin',
posts : [postIds[2]]
});
posts.push({
_id : postIds[0],
title : 'post-by-aikin',
poster : userIds[0],
comments : [commentIds[0]]
});
posts.push({
_id : postIds[1],
title : 'post-by-luna',
poster : userIds[1],
comments : [commentIds[1]]
});
posts.push({
_id : postIds[2],
title : 'post-by-luajin',
poster : userIds[2],
comments : [commentIds[2]]
});
comments.push({
_id : commentIds[0],
content : 'comment-by-luna',
commenter : userIds[1],
post : postIds[0]
});
comments.push({
_id : commentIds[1],
content : 'comment-by-luajin',
commenter : userIds[2],
post : postIds[1]
});
comments.push({
_id : commentIds[2],
content : 'comment-by-aikin',
commenter : userIds[1],
post : postIds[2]
});
User.create(users, function(err, docs) {
Post.create(posts, function(err, docs) {
Comment.create(comments, function(err, docs) {
// run example on here
});
});
});
}
// Query#populate examples
function example1(done) {
User.find()
.populate('posts', 'title', null, {sort: { title: -1 }})
.exec(function(err, docs) {
console.log(docs[0].posts[0].title); // post-by-aikin
});
User.findOne({name: 'luajin'})
.populate({path: 'posts', select: { title: 1 }, options: {sort: { title: -1 }}})
.exec(function(err, doc) {
console.log(doc.posts[0].title); // post-by-luajin
});
}
function example2(done) {
Post.findOne({title: 'post-by-aikin'})
.populate('poster comments', '-_id')
.exec(function(err, doc) {
console.log(doc.poster.name); // aikin
console.log(doc.poster._id); // undefined
console.log(doc.comments[0].content); // comment-by-luna
console.log(doc.comments[0]._id); // undefined
});
Post.findOne({title: 'post-by-aikin'})
.populate({path: 'poster comments', select: '-_id'})
.exec(function(err, doc) {
console.log(doc.poster.name); // aikin
console.log(doc.poster._id); // undefined
console.log(doc.comments[0].content); // comment-by-luna
console.log(doc.comments[0]._id); // undefined
});
Post.findOne({title: 'post-by-aikin'})
.populate(['poster', 'comments'])
.exec(function(err, doc) {
console.log(doc.poster.name); // aikin
console.log(doc.comments[0].content); // comment-by-luna
});
Post.findOne({title: 'post-by-aikin'})
.populate([
{path:'poster', select: '-_id'},
{path:'comments', select: '-content'}
])
.exec(function(err, doc) {
console.log(doc.poster.name); // aikin
console.log(doc.poster._id); // undefined
console.log(doc.comments[0]._id); // 会打印出对应的 comment id
console.log(doc.comments[0].content); // undefined
});
}
// Model#populate example
function example3(done) {
Post.find({title: 'post-by-aikin'})
.populate('poster comments')
.exec(function(err, docs) {
var opts = [{
path : 'comments.commenter',
select : 'name',
model : 'User'
}];
Post.populate(docs, opts, function(err, populatedDocs) {
console.log(populatedDocs[0].poster.name); // aikin
console.log(populatedDocs[0].comments[0].commenter.name); // luna
done();
});
});
}
// Document#populate example
function example4(done) {
User.findOne({name: 'aikin'})
.exec(function(err, doc) {
var opts = [{
path : 'posts',
select : 'title'
}];
doc.populate(opts, function(err, populatedDoc) {
console.log(populatedDoc.posts[0].title); // post-by-aikin
done();
});
});
}
function done(){
mongoose.connection.db.dropDatabase(function() {
mongoose.connection.close();
});
}
@simuty
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simuty commented May 23, 2017

非常感谢博主提供的实例代码。
发现一个问题,模拟填充数据时,用户名与ID不匹配。

    comments.push({
        _id       : commentIds[2],
        content   : 'comment-by-aikin',
//aikin的userIds是0
        commenter : userIds[1],
        post      : postIds[2]
    });

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