Query Helpers in TypeScriptTypeScript中的查询帮助程序

Query helpers查询帮助程序 let you define custom helper methods on Mongoose queries. Query helpers make queries more semantic using chaining syntax.让您可以在Mongoose查询上定义自定义助手方法。查询助手使用链接语法使查询更具语义。

The following is an example of how query helpers work in JavaScript.以下是查询助手如何在JavaScript中工作的示例。

ProjectSchema.query.byName = function(name) {
  return this.find({ name: name });
};
const Project = mongoose.model('Project', ProjectSchema);

// Works. Any Project query, whether it be `find()`, `findOne()`,
// `findOneAndUpdate()`, `delete()`, etc. now has a `byName()` helper
Project.find().where('stars').gt(1000).byName('mongoose');

Manually Typed Query Helpers手动键入的查询帮助程序

In TypeScript, you can define query helpers using a separate query helpers interface. 在TypeScript中，可以使用单独的查询助手接口定义查询助手。Mongoose's Model takes 3 generic parameters:Mongoose的Model采用3个通用参数：

1. The DocType
2. a TQueryHelpers type
3. a TMethods type

The 2nd generic parameter, TQueryHelpers, should be an interface that contains a function signature for each of your query helpers. 第二个通用参数TQueryHelpers应该是一个包含每个查询助手的函数签名的接口。Below is an example of creating a ProjectModel with a byName query helper.以下是使用byName查询帮助程序创建ProjectModel的示例。

import { HydratedDocument, Model, Query, Schema, model } from 'mongoose';

interface Project {
  name?: string;
  stars?: number;
}

interface ProjectQueryHelpers {
  byName(name: string): QueryWithHelpers<
    HydratedDocument<Project>[],
    HydratedDocument<Project>,
    ProjectQueryHelpers
  >
}

type ProjectModelType = Model<Project, ProjectQueryHelpers>;

const ProjectSchema = new Schema<
  Project,
  Model<Project, ProjectQueryHelpers>,
  {},
  ProjectQueryHelpers
>({
  name: String,
  stars: Number
});

ProjectSchema.query.byName = function byName(
  this: QueryWithHelpers<any, HydratedDocument<Project>, ProjectQueryHelpers>,
  name: string
) {
  return this.find({ name: name });
};

// 2nd param to `model()` is the Model class to return.
const ProjectModel = model<Project, ProjectModelType>('Project', schema);

run().catch(err => console.log(err));

async function run(): Promise<void> {
  await connect('mongodb://127.0.0.1:27017/test');

  // Equivalent to `ProjectModel.find({ stars: { $gt: 1000 }, name: 'mongoose' })`
  await ProjectModel.find().where('stars').gt(1000).byName('mongoose');
}

Auto Typed Query Helpers自动键入的查询帮助程序

Mongoose does support auto typed Query Helpers that it are supplied in schema options. Mongoose确实支持模式选项中提供的自动类型查询帮助程序。Query Helpers functions can be defined as following:查询帮助程序功能可以定义如下：

import { Schema, model } from 'mongoose';

const ProjectSchema = new Schema({
  name: String,
  stars: Number
}, {
  query: {
    byName(name: string) {
      return this.find({ name });
    }
  }
});

const ProjectModel = model('Project', ProjectSchema);

// Equivalent to `ProjectModel.find({ stars: { $gt: 1000 }, name: 'mongoose' })`
await ProjectModel.find().where('stars').gt(1000).byName('mongoose');