创建后如何在mongoose中填充子文档？

Question

我正在为item.comments列表添加评论.我需要在我在响应中输出之前获取comment.created_by用户数据.我该怎么做？

    Item.findById(req.param('itemid'), function(err, item){
        var comment = item.comments.create({
            body: req.body.body
            , created_by: logged_in_user
        });

        item.comments.push(comment);

        item.save(function(err, item){
            res.json({
                status: 'success',
                message: "You have commented on this item",

//how do i populate comment.created_by here???

                comment: item.comments.id(comment._id)
            });
        }); //end item.save
    }); //end item.find

我需要在res.json输出中填充comment.created_by字段:

                comment: item.comments.id(comment._id)

comment.created_by是我的mongoose CommentSchema中的用户引用.它目前只给我一个用户ID,我需要填充所有用户数据,密码和盐字段除外.

以下是人们提出的架构:

var CommentSchema = new Schema({
    body          : { type: String, required: true }
  , created_by    : { type: Schema.ObjectId, ref: 'User', index: true }
  , created_at    : { type: Date }
  , updated_at    : { type: Date }
});

var ItemSchema = new Schema({
    name    : { type: String, required: true, trim: true }
  , created_by  : { type: Schema.ObjectId, ref: 'User', index: true }
  , comments  : [CommentSchema]
});

Answer 1

为了填充引用的子文档,您需要显式定义ID引用的文档集合(例如created_by: { type: Schema.Types.ObjectId, ref: 'User' }).

鉴于此引用已定义且您的架构也已明确定义,您现在可以populate像往常一样调用(例如populate('comments.created_by'))

概念证明代码:

// Schema
var mongoose = require('mongoose');
var Schema = mongoose.Schema;

var UserSchema = new Schema({
  name: String
});

var CommentSchema = new Schema({
  text: String,
  created_by: { type: Schema.Types.ObjectId, ref: 'User' }
});

var ItemSchema = new Schema({
   comments: [CommentSchema]
});

// Connect to DB and instantiate models    
var db = mongoose.connect('enter your database here');
var User = db.model('User', UserSchema);
var Comment = db.model('Comment', CommentSchema);
var Item = db.model('Item', ItemSchema);

// Find and populate
Item.find({}).populate('comments.created_by').exec(function(err, items) {
    console.log(items[0].comments[0].created_by.name);
});

最后请注意,这populate仅适用于查询,因此您需要先将项目传递给查询,然后调用它:

item.save(function(err, item) {
    Item.findOne(item).populate('comments.created_by').exec(function (err, item) {
        res.json({
            status: 'success',
            message: "You have commented on this item",
            comment: item.comments.id(comment._id)
        });
    });
});

Answer 2

自编写原始答案以来,这可能已经改变,但看起来您现在可以使用Models populate函数来执行此操作,而无需执行额外的findOne.请参阅:http://mongoosejs.com/docs/api.html#model_Model.populate.您可以像在findOne中一样在保存处理程序中使用它.

Answer 3

@ user1417684和@ chris-foster是对的!

从工作代码中摘录(没有错误处理):

var SubItemModel = mongoose.model('subitems', SubItemSchema);
var ItemModel    = mongoose.model('items', ItemSchema);

var new_sub_item_model = new SubItemModel(new_sub_item_plain);
new_sub_item_model.save(function (error, new_sub_item) {

  var new_item = new ItemModel(new_item);
  new_item.subitem = new_sub_item._id;
  new_item.save(function (error, new_item) {
    // so this is a valid way to populate via the Model
    // as documented in comments above (here @stack overflow):
    ItemModel.populate(new_item, { path: 'subitem', model: 'subitems' }, function(error, new_item) {
      callback(new_item.toObject());
    });
    // or populate directly on the result object
    new_item.populate('subitem', function(error, new_item) {
      callback(new_item.toObject());
    });
  });

});