填充多个级别不起作用

First = new mongoose.Schema({ name: String, second: {type: Schema.Types.ObjectId, ref: 'Second'}, }); Second = new mongoose.Schema({ name: String, third: {type: Schema.Types.ObjectId, ref: 'Third'}, }); Third = new mongoose.Schema({ name: String }); First.find({}).populate({ path: 'Second', populate: { path: 'Third'} }).exec(function(err, result) { console.log(result) }) 

首先填充是好的，但第三总是null 。 意思是我有这样的一些东西：

 { name: 1, second: { name: 2, third: null }} 

Answer 1

 var mongoose = require('mongoose'); var Schema = mongoose.Schema; mongoose.connect('mongodb://localhost/test'); var FirstSchema = new mongoose.Schema({ name: String, second: {type: Schema.Types.ObjectId, ref: 'Second'}, }); var SecondSchema = new mongoose.Schema({ name: String, third: {type: Schema.Types.ObjectId, ref: 'Third'}, }); var ThirdSchema = new mongoose.Schema({ name: String }); var First = mongoose.model('First', FirstSchema); var Second = mongoose.model('Second', SecondSchema); var Third = mongoose.model('Third', ThirdSchema); First.remove({}).exec(); Second.remove({}).exec(); Third.remove({}).exec(); var _3 = new Third({name: 'third'}); _3.save(function(err1) { if (err1) { throw err1; } var _2 = new Second({name: 'second', third: _3.id}); _2.save(function(err2) { if (err2) { throw err2; } var _1 = new First({name: 'first', second: _2.id}); _1.save(function() { First.find({}).populate({ path: 'second', populate: { path: 'third'} }).exec(function(err, result) { console.log(result[0]); }); }); }); }); 

有没有你的path分配了一个错误的值或什么的？

它应该是一个字段名称，而不是一个对象名称