使用带有 Refs 和 Promise 的嵌套模式保存和查找 Mongoose 文档

Question

我有一个相当简单的问题。我正在尝试保存其架构包含嵌套架构引用的文档，并且该架构引用包含另一个架构引用。但是，当我去检索该文档时，它不包括（必需的）嵌套字段，除非我在同一个查询中填充它。然而，即使我填充了查询，第二个嵌套文档也没有填充。我是否误解了关于 refs 在 mongoose 中的工作方式的一些基本内容？

JavaScript 和 LiveScript 示例代码和输出如下。

---

JavaScript：

(function(){
  var mongoose, bookSchemaObj, authorSchemaObj, agentSchemaObj, bookSchema, authorSchema, agentSchema, Book, Author, Agent, testBookObj, testAuthorObj, testAgentObj, testAgent, testAuthor, testBook;
  mongoose = require("mongoose-bird")(require("mongoose"));
  mongoose.connect("mongodb://test:test@localhost:27017/test");
  bookSchemaObj = {
    author: {
      type: mongoose.Schema.Types.ObjectId,
      ref: "Author",
      required: true
    },
    pubYear: {
      type: Number
    }
  };
  authorSchemaObj = {
    name: {
      type: String,
      required: true
    },
    agent: {
      type: mongoose.Schema.Types.ObjectId,
      ref: "Agent",
      required: true
    }
  };
  agentSchemaObj = {
    name: {
      type: String,
      required: true
    }
  };
  bookSchema = new mongoose.Schema(bookSchemaObj);
  authorSchema = new mongoose.Schema(authorSchemaObj);
  agentSchema = new mongoose.Schema(agentSchemaObj);
  Book = mongoose.model("Book", bookSchema);
  Author = mongoose.model("Author", authorSchema);
  Agent = mongoose.model("Agent", agentSchema);
  testBookObj = {
    pubYear: 2001
  };
  testAuthorObj = {
    name: "John P. Doe"
  };
  testAgentObj = {
    name: "Alfred O. Thompson"
  };
  testAgent = new Agent(testAgentObj);
  testAuthor = new Author(testAuthorObj);
  testBook = new Book(testBookObj);
  testAuthor.agent = testAgent._id;
  testBook.author = testAuthor._id;
  testAgent.saveAsync().then(function(){
    return testAuthor.saveAsync();
  }).then(function(){
    return testBook.saveAsync();
  }).then(function(){
    console.log("book after saving agent, author, and book:");
    console.log(JSON.stringify(testBook, undefined, 2));
    console.log("");
    return Author.findById(testAuthor._id).populate("agent").execAsync();
  }).then(function(queriedAuthor){
    console.log("author after finding and populating author");
    console.log(JSON.stringify(queriedAuthor, undefined, 2));
    console.log("");
    return Book.findById(testBook._id).populate("author author.agent").execAsync();
  }).then(function(queriedBook){
    console.log("book after finding and populating book: ");
    console.log(JSON.stringify(queriedBook, undefined, 2));
    console.log("");
    return Book.findByIdAsync(testBook._id);
  }).then(function(foundBooks){
    console.log("book after finding book:");
    console.log(JSON.stringify(foundBooks, undefined, 2));
    console.log("");
    return foundBooks.populateAsync("author");
  }).then(function(populatedBook){
    console.log("book after populating book: ");
    console.log(JSON.stringify(populatedBook, undefined, 2));
    process.exit();
  })['catch'](function(err){
    console.log(err);
  });
}).call(this);

---

LiveScript：

mongoose = require("mongoose-bird")(require("mongoose"))
mongoose.connect "mongodb://test:test@localhost:27017/test"

bookSchemaObj   =
  author:
    type: mongoose.Schema.Types.ObjectId
    ref: "Author"
    required: true
  pubYear:
    type: Number

authorSchemaObj =
  name:
    type: String
    required: true
  agent:
    type: mongoose.Schema.Types.ObjectId
    ref: "Agent"
    required: true

agentSchemaObj  =
  name:
    type: String
    required: true

bookSchema   = new mongoose.Schema bookSchemaObj
authorSchema = new mongoose.Schema authorSchemaObj
agentSchema  = new mongoose.Schema agentSchemaObj

Book   = mongoose.model "Book", bookSchema
Author = mongoose.model "Author", authorSchema
Agent  = mongoose.model "Agent", agentSchema

testBookObj   =
  pubYear: 2001

testAuthorObj =
  name: "John P. Doe"

testAgentObj  =
  name: "Alfred O. Thompson"

testAgent  = new Agent testAgentObj
testAuthor = new Author testAuthorObj
testBook   = new Book testBookObj

testAuthor.agent = testAgent._id
testBook.author  = testAuthor._id

testAgent.saveAsync!
  .then ->
    return testAuthor.saveAsync!

  .then ->
    return testBook.saveAsync!

  .then ->
    console.log "book after saving agent, author, and book:"
    console.log JSON.stringify testBook, undefined, 2
    console.log ""
    return Author.findById(testAuthor._id).populate("agent").execAsync!

  .then (queriedAuthor) ->
    console.log "author after finding and populating author"
    console.log JSON.stringify queriedAuthor, undefined, 2
    console.log ""
    return Book.findById(testBook._id).populate("author author.agent")
      .execAsync!

  .then (queriedBook) ->
    console.log "book after finding and populating book: "
    console.log JSON.stringify queriedBook, undefined, 2
    console.log ""
    return Book.findByIdAsync testBook._id

  .then (foundBooks) ->
    console.log "book after finding book:"
    console.log JSON.stringify foundBooks, undefined, 2
    console.log ""
    return foundBooks.populateAsync "author"

  .then (populatedBook) !->
    console.log "book after populating book: "
    console.log JSON.stringify populatedBook, undefined, 2
    process.exit!

  .catch (err) !->
    console.log err

---

输出：

book after saving agent, author, and book:
{
  "__v": 0,
  "author": "553a52d4cd8d2a4f5a5c4185",
  "pubYear": 2001,
  "_id": "553a52d4cd8d2a4f5a5c4186"
}

author after finding and populating author
{
  "_id": "553a52d4cd8d2a4f5a5c4185",
  "agent": {
    "_id": "553a52d4cd8d2a4f5a5c4184",
    "name": "Alfred O. Thompson",
    "__v": 0
  },
  "name": "John P. Doe",
  "__v": 0
}

book after finding and populating book: 
{
  "_id": "553a52d4cd8d2a4f5a5c4186",
  "author": {
    "_id": "553a52d4cd8d2a4f5a5c4185",
    "name": "John P. Doe",
    "__v": 0
  },
  "pubYear": 2001,
  "__v": 0
}

book after finding book:
{
  "_id": "553a52d4cd8d2a4f5a5c4186",
  "pubYear": 2001,
  "__v": 0
}

book after populating book: 
{
  "_id": "553a52d4cd8d2a4f5a5c4186",
  "pubYear": 2001,
  "__v": 0
}

Answer 1

可以通过调用Model.populate ad infinitum 来实现多层深度引用的递归填充，以填充跨越超过 2 个集合的结构。

在多级深度引用的情况下，多重填充 populate("author author.agent") 不起作用。您必须先填充author，然后在Agent 上填充author.agent。

如果您不知道要填充其 ID 的代理，请 findById 并填充作者，然后使用范围超出承诺的变量来存储填充的代理 ID，然后重新添加它，然后使用 Agent 填充。填充。

var agentId = null;

testAgent.saveAsync().then(function(){
    return testAuthor.saveAsync();
}).then(function(){
    return testBook.saveAsync();
}).then(function(){
    return Author.findById(testAuthor._id).populate("agent").execAsync!
}).then(function(populatedAuthor){
    console.log("book after saving agent, author, and book:");
    console.log(JSON.stringify(testBook, undefined, 2));
    console.log("");
    agentId = populatedAuthor.agent._id;
    return Book.findById(testBook._id).populate("author").execAsync();
}).then(function(partiallyPopulatedBook){
    console.log("author after finding and populating author:");
    console.log(JSON.stringify(partiallyPopulatedBook, undefined, 2));
    console.log("");
    partiallyPopulatedBook.author.agent = agentId;
    return Agent.populate(partiallyPopulatedBook, {path:"author.agent"});
}).then(function(populatedBook){
    console.log("author after finding and populating author and autho.agent:");
    console.log(JSON.stringify(populatedBook, undefined, 2));
    process.exit();
})['catch'](function(err){
    console.log(err);
});