猫鼬填充嵌套数组 [英] Mongoose populate nested array

问题描述

假设以下3个模型:

var CarSchema = new Schema({
  name: {type: String},
  partIds: [{type: Schema.Types.ObjectId, ref: 'Part'}],
});

var PartSchema = new Schema({
  name: {type: String},
  otherIds: [{type: Schema.Types.ObjectId, ref: 'Other'}],
});

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

查询汽车时，我可以填充零件:

When I query for Cars I can populate the parts:

Car.find().populate('partIds').exec(function(err, cars) {
  // list of cars with partIds populated
});

猫鼬是否有办法在所有汽车的嵌套零件对象中填充otherIds.

Is there a way in mongoose to populate the otherIds in the nested parts objects for all the cars.

Car.find().populate('partIds').exec(function(err, cars) {
  // list of cars with partIds populated
  // Try an populate nested
  Part.populate(cars, {path: 'partIds.otherIds'}, function(err, cars) {
    // This does not populate all the otherIds within each part for each car
  });
});

我可能可以遍历每辆车并尝试填充:

I can probably iterate over each car and try to populate:

Car.find().populate('partIds').exec(function(err, cars) {
  // list of cars with partIds populated

  // Iterate all cars
  cars.forEach(function(car) {
     Part.populate(car, {path: 'partIds.otherIds'}, function(err, cars) {
       // This does not populate all the otherIds within each part for each car
     });
  });
});

问题是我必须使用async之类的库来对每个对象进行填充调用，然后等到所有操作完成后再返回.

Problem there is that I have to use a lib like async to make the populate call for each and wait until all are done and then return.

有可能不循环所有汽车吗?

Possible to do without looping over all cars?

推荐答案

更新:请参阅 Trinh Hoang Nhu的答案是Mongoose 4中添加的更紧凑的版本.总结如下:

Update: Please see Trinh Hoang Nhu's answer for a more compact version that was added in Mongoose 4. Summarized below:

Car
  .find()
  .populate({
    path: 'partIds',
    model: 'Part',
    populate: {
      path: 'otherIds',
      model: 'Other'
    }
  })

---

猫鼬3及以下:

Car
  .find()
  .populate('partIds')
  .exec(function(err, docs) {
    if(err) return callback(err);
    Car.populate(docs, {
      path: 'partIds.otherIds',
      model: 'Other'
    },
    function(err, cars) {
      if(err) return callback(err);
      console.log(cars); // This object should now be populated accordingly.
    });
  });

对于这样的嵌套种群，您必须告诉猫鼬您想从中填充的模式.

For nested populations like this, you have to tell mongoose the Schema you want to populate from.

这篇关于猫鼬填充嵌套数组的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！