在 TypeScript 中处理子文档

¥Handling Subdocuments in TypeScript

TypeScript 中的子文档很棘手。默认情况下，Mongoose 将文档接口中的对象属性视为嵌套属性而不是子文档。

¥Subdocuments are tricky in TypeScript. By default, Mongoose treats object properties in document interfaces as nested properties rather than subdocuments.

// Setup
import { Schema, Types, model, Model } from 'mongoose';

// Subdocument definition
interface Names {
  _id: Types.ObjectId;
  firstName: string;
}

// Document definition
interface User {
  names: Names;
}

// Models and schemas
type UserModelType = Model<User>;
const userSchema = new Schema<User, UserModelType>({
  names: new Schema<Names>({ firstName: String })
});
const UserModel = model<User, UserModelType>('User', userSchema);

// Create a new document:
const doc = new UserModel({ names: { _id: '0'.repeat(24), firstName: 'foo' } });

// "Property 'ownerDocument' does not exist on type 'Names'."
// Means that `doc.names` is not a subdocument!
doc.names.ownerDocument();

Mongoose 提供了一种覆盖水合文档中类型的机制。定义一个单独的 THydratedDocumentType 并将其作为第 5 个通用参数传递给 mongoose.Model<>。THydratedDocumentType 控制 Mongoose 对 "水合文档" 使用的类型，即 await UserModel.findOne()、UserModel.hydrate() 和 new UserModel() 返回的类型。

¥Mongoose provides a mechanism to override types in the hydrated document. Define a separate THydratedDocumentType and pass it as the 5th generic param to mongoose.Model<>. THydratedDocumentType controls what type Mongoose uses for "hydrated documents", that is, what await UserModel.findOne(), UserModel.hydrate(), and new UserModel() return.

// Define property overrides for hydrated documents
type THydratedUserDocument = {
  names?: mongoose.Types.Subdocument<Names>
}
type UserModelType = mongoose.Model<User, {}, {}, {}, THydratedUserDocument>;

const userSchema = new mongoose.Schema<User, UserModelType>({
  names: new mongoose.Schema<Names>({ firstName: String })
});
const UserModel = mongoose.model<User, UserModelType>('User', userSchema);

const doc = new UserModel({ names: { _id: '0'.repeat(24), firstName: 'foo' } });
doc.names!.ownerDocument(); // Works, `names` is a subdocument!

子文档数组

¥Subdocument Arrays

你还可以使用 TMethodsAndOverrides 覆盖数组以正确键入子文档数组：

¥You can also override arrays to properly type subdocument arrays using TMethodsAndOverrides:

// Subdocument definition
interface Names {
  _id: Types.ObjectId;
  firstName: string;
}
// Document definition
interface User {
  names: Names[];
}

// TMethodsAndOverrides
type THydratedUserDocument = {
  names?: Types.DocumentArray<Names>
}
type UserModelType = Model<User, {}, {}, {}, THydratedUserDocument>;

// Create model
const UserModel = model<User, UserModelType>('User', new Schema<User, UserModelType>({
  names: [new Schema<Names>({ firstName: String })]
}));

const doc = new UserModel({});
doc.names[0].ownerDocument(); // Works!