使用Mongoose查询嵌套嵌套文档 [英] Querying nested embedded documents with Mongoose

问题描述

我想在嵌套的嵌入文档中查询。我尝试填充结果，但是失败。

I'm trying to query inside an embedded document that is nested. I've attempted to 'populate' the results but that fails.

如何获取查找调用中的所有图书详细信息？我想在用户货架上的所有图书对象，我可以从中获取数据？

How do I get back all of the book details inside the find call? I want all of the book objects on a users shelf that I can get data from?

###

Trying to query nested embedded documents using Mongoose.

Database Outline for example

An Owner has multiple bookshelves which each have an array of books.
A book is not unique, and the same book could be on many different shelves.

###

mongoose = require("mongoose")
Schema = mongoose.Schema
mongoose.connect "localhost", "d1"

bookSchema = new Schema(title: String)
Book = mongoose.model("Book", bookSchema)

shelfBookSchema = new Schema(
  book:
    type: Schema.ObjectId
    ref: "Book"
  )

shelfSchema = new Schema(
  name: String
  books: [ shelfBookSchema ]
  )

Shelf = mongoose.model("Shelf", shelfSchema)

ownerSchema = new Schema(
  firstName: String
  shelves: [ shelfSchema ]
  )

Owner = mongoose.model("Owner", ownerSchema)

mongoose.connection.on "open", ->
  book1 = new Book(title:"How to make stuff")
  book1.save (err) ->
    throw err if err

    owner = new Owner(firstName:"John")
    shelf = new Shelf(name:"DIY Shelf")
    shelf.books.push
      _id: book1._id
      book: book1._id
    owner.shelves.push shelf
    owner.save (err) ->
      throw err if err

      #Let's find one owner and get all of his bookshelves and the books they containa
      Owner.findOne().populate("shelves.books.book").exec (err, owner) ->
        console.error owner.shelves[0].books

        ### Log shows:

        { book: 4fe3047401fc23e79c000003,
        _id: 4fe3047401fc23e79c000003 }]

        Great but how do I get the values of book like the title etc??

        ###

        mongoose.connection.db.dropDatabase ->
          mongoose.connection.close()

推荐答案

在蒙古人3.6中增加了深度种群。 https://github.com/LearnBoost/mongoose/issues/1377#issuecomment-15911192

Deep population was added in Mongoose 3.6. https://github.com/LearnBoost/mongoose/issues/1377#issuecomment-15911192

对于你的例子，它会是这样：

For your example, it would be something like:

Owner.find().populate('shelves').exec(PopulateBooks);

function PopulateBooks(err, owners) {
      if(err) throw err;
      // Deep population is here
      Book.populate(owners, { path: 'shelves.books' }).exec(callback);
}

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