stackoverflow 上似乎有很多关于此主题的 Q/A,但我似乎无法在任何地方找到确切的答案。
我有什么:
我有公司和个人模型:
var mongoose = require('mongoose');
var PersonSchema = new mongoose.Schema{
name: String,
lastname: String};
// company has a reference to Person
var CompanySchema = new mongoose.Schema{
name: String,
founder: {type:Schema.ObjectId, ref:Person}};
我需要什么:
查找姓氏为“Robertson”的人创建的所有公司
我尝试了什么:
Company.find({'founder.id': 'Robertson'}, function(err, companies){
console.log(companies); // getting an empty array
});
然后我发现 Person 不是嵌入的而是引用的,所以我使用 populate 来填充创始人-Person,然后尝试使用带有 'Robertson' lastname 的 find
// 1. retrieve all companies
// 2. populate their founders
// 3. find 'Robertson' lastname in populated Companies
Company.find({}).populate('founder')
.find({'founder.lastname': 'Robertson'})
.exec(function(err, companies) {
console.log(companies); // getting an empty array again
});
我仍然可以用 Person 的 id 作为字符串来查询公司。但这并不是我想要的,正如你所理解的那样
Company.find({'founder': '525cf76f919dc8010f00000d'}, function(err, companies){
console.log(companies); // this works
});
最佳答案
您不能在单个查询中执行此操作,因为 MongoDB 不支持连接。相反,您必须将其分解为几个步骤:
// Get the _ids of people with the last name of Robertson.
Person.find({lastname: 'Robertson'}, {_id: 1}, function(err, docs) {
// Map the docs into an array of just the _ids
var ids = docs.map(function(doc) { return doc._id; });
// Get the companies whose founders are in that set.
Company.find({founder: {$in: ids}}, function(err, docs) {
// docs contains your answer
});
});
关于node.js - Mongoose 通过其引用模型的字段对模型进行嵌套查询,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/19380738/