ReactiveX 学习笔记（25）使用 RxJS + Vue.js 调用 REST API

JSON : Placeholder

JSON : Placeholder (https://jsonplaceholder.typicode.com/) 是一个用于测试的 REST API 网站。
以下使用 RxJS6 + Angular 6 调用该网站的 REST API，获取字符串以及 JSON 数据。

• GET /posts/1
• GET /posts
• POST /posts
• PUT /posts/1
• DELETE /posts/1

所有 GET API 都返回JSON数据，格式（JSON-Schema）如下：

{
  "type":"object",
  "properties": {
    "userId": {"type" : "integer"},
    "id": {"type" : "integer"},
    "title": {"type" : "string"},
    "body": {"type" : "string"}
  }
}

创建工程

# 安装 Vue CLI
$ npm install --global @vue/cli
# 创建新的应用程序 RxExample
$ vue create rx-example
# 选择 Manually select features
# 选择 Babel 和 TypeScript Linter/Formatter
$ cd rx-example
$ npm run serve

打开 Intellij IDEA, File / New / Project From Existing Sources...，然后选中工程所在文件夹
在向导的第1页选择 Create project from existing sources
完成向导后在点击 Finish 创建工程。

点击 Add Configurations, 点击 +npm
Name: Vue CLI Server
Scripts: serve
点击 OK 完成配置。
点击 Vue CLI Server 启动程序。
http://localhost:8080/ 可打开网页。

Post

在 src 文件夹下添加 post.ts，内容如下

export class Post {
  userId!: number;
  id!: number;
  title!: string;
  body!: string;
  toString(): string {
    return `Post {userId = ${this.userId}, id = ${this.id}, title = "${this.title}", body = "${this.body.replace(/\n/g, '\\n')}"}`;
  }
}

安装 vue-typescript-inject

vue-typescript-inject 是一个在 Vue.js 中实现 DI（依赖注入） 的包。
需要安装 vue-typescript-inject 和 reflect-metadata

$ npm i vue-typescript-inject reflect-metadata

打开 tsconfig.json 在 compilerOptions 中
添加关于 emitDecoratorMetadata 的设定。

    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,

打开 main.ts 在 Vue 对象生成的代码之前
添加以下三行代码。

import 'reflect-metadata';
import VueTypeScriptInject from 'vue-typescript-inject';
Vue.use(VueTypeScriptInject); // register vue-typescript-inject

添加 Rxios

访问 API 采用将 rxjs 和 axios 合为一体的 Rxios 组件，但是该组件尚未升级到 rxjs6。
这里我们只安装 rxjs 和 axios，然后直接以源码形式引入 Rxios，并将其升级到 rxjs6。

$ npm install axios rxjs

在 src 文件夹下添加 rxios.ts，内容如下

// https://github.com/davguij/rxios/blob/master/src/index.ts
// ported to rxjs6

import axios, { AxiosInstance, AxiosRequestConfig, AxiosPromise } from 'axios';
// import { Observable } from 'rxjs/Observable';
import { Observable } from 'rxjs';

export interface rxiosConfig extends AxiosRequestConfig {
  localCache?: boolean;
}

class rxios {
  private _httpClient: AxiosInstance;

  constructor(private options: rxiosConfig = {}) {
    this._httpClient = axios.create(options);
  }

  private _makeRequest<T>(method: string, url: string, queryParams?: object, body?: object) {
    let request: AxiosPromise<T>;
    switch (method) {
      case 'GET':
        request = this._httpClient.get<T>(url, {params: queryParams});
        break;
      case 'POST':
        request = this._httpClient.post<T>(url, body, {params: queryParams});
        break;
      case 'PUT':
        request = this._httpClient.put<T>(url, body, {params: queryParams});
        break;
      case 'PATCH':
        request = this._httpClient.patch<T>(url, body, {params: queryParams});
        break;
      case 'DELETE':
        request = this._httpClient.delete(url, {params: queryParams});
        break;

      default:
        throw new Error('Method not supported');
    }
    return new Observable<T>(subscriber => {
      request.then(response => {
        subscriber.next(response.data);
        subscriber.complete();
      }).catch((err: Error) => {
        subscriber.error(err);
        subscriber.complete();
      });
    });
  }

  public get<T>(url: string, queryParams?: object) {
    return this._makeRequest<T>('GET', url, queryParams);
  }

  public post<T>(url: string, body: object, queryParams?: object) {
    return this._makeRequest<T>('POST', url, queryParams, body);
  }

  public put<T>(url: string, body: object, queryParams?: object) {
    return this._makeRequest<T>('PUT', url, queryParams, body);
  }

  public patch<T>(url: string, body: object, queryParams?: object) {
    return this._makeRequest<T>('PATCH', url, queryParams, body);
  }

  public delete(url: string, queryParams?: object) {
    return this._makeRequest('DELETE', url, queryParams);
  }
}

export {rxios, rxios as Rxios};

post 服务

在 src 文件夹下添加 post.service.ts，内容如下

import { injectable } from 'vue-typescript-inject';
import {of, Observable, from} from 'rxjs';
import {map, mergeAll, take, tap} from 'rxjs/operators';
import { Post } from './post';
import { Rxios } from '@/rxios';

@injectable()
export class PostService {
  private readonly http = new Rxios();
  private readonly baseUrl = 'http://jsonplaceholder.typicode.com/';

  constructor() {
    this.getPostAsString().subscribe();
    this.getPostAsJson().subscribe();
    this.getPosts(2).subscribe();
    this.createPost().subscribe();
    this.updatePost().subscribe();
    this.deletePost().subscribe();
  }

  private getPostAsString(): Observable<string> {
    const url = `${this.baseUrl}posts/1`;
    return this.http.get(url, { responseType: 'text' })
      .pipe(
        tap((result: any) => console.log(result)),
      );
  }

  private getPostAsJson(): Observable<Post> {
    const url = `${this.baseUrl}posts/1`;
    return this.http.get<Post>(url)
      .pipe(
        map((result: any) => Object.assign(new Post(), result)),
        tap((result: any) => console.log('' + result)),
      );
  }

  private getPosts(n: number): Observable<Post> {
    const url = `${this.baseUrl}posts`;
    return from(this.http.get<Post[]>(url))
      .pipe(
        mergeAll(),
        map((result: any) => Object.assign(new Post(), result)),
        take(n),
        tap((result: any) => console.log('' + result)),
      );
  }

  private createPost(): Observable<string> {
    const url = `${this.baseUrl}posts`;
    return this.http.post(url, {
      params: {
        userId: 101,
        title: 'test title',
        body: 'test body',
      }
    })
      .pipe(
        map((result: any) => JSON.stringify(result)),
        tap((result: any) => console.log(result)),
      );
  }

  private updatePost(): Observable<string> {
    const url = `${this.baseUrl}posts/1`;
    return this.http.put(url, {
      params: {
        userId: 101,
        title: 'test title',
        body: 'test body',
      }
    })
      .pipe(
        map((result: any) => JSON.stringify(result)),
        tap((result: any) => console.log(result)),
      );
  }

  private deletePost(): Observable<string> {
    const url = `${this.baseUrl}posts/1`;
    return this.http.delete(url)
      .pipe(
        map((result: any) => JSON.stringify(result)),
        tap((result: any) => console.log(result)),
      );
  }
}

• getPostAsString 方法取出第1个Post，返回字符串
• getPostAsJson 方法取出第1个Post，返回Post对象
• getPosts 方法取出前n个Post，返回n个Post对象
• createPost 方法创建1个Post，返回字符串
• updatePost 方法更新第1个Post，返回字符串
• deletePost 方法删除第1个Post，返回字符串

app.module.ts 中添加 PostService 和 HttpClientModule 的引用。

import { PostService } from './post.service';
import { HttpClientModule } from '@angular/common/http';

@NgModule({
  imports: [
    BrowserModule,
    HttpClientModule,
  ],
  providers: [
    PostService,
  ],
})

删除 HelloWorld 组件，即 src/components/HelloWorld.vue 文件。

打开 App.vue，将其改为

<template>
</template>

<script lang="ts">
import { Component, Vue } from 'vue-property-decorator';
import { PostService } from './post.service';

@Component({
  providers: [
    PostService,
  ],
})
export default class App extends Vue {}
</script>

<style>
</style>

输出结果

{
  "userId": 1,
  "id": 1,
  "title": "sunt aut facere repellat provident occaecati excepturi optio reprehenderit",
  "body": "quia et suscipit\nsuscipit recusandae consequuntur expedita et cum\nreprehenderit molestiae ut ut quas totam\nnostrum rerum est autem sunt rem eveniet architecto"
}
Post {userId = 1, id = 1, title = "sunt aut facere repellat provident occaecati excepturi optio reprehenderit", body = "quia et suscipit\nsuscipit recusandae consequuntur expedita et cum\nreprehenderit molestiae ut ut quas totam\nnostrum rerum est autem sunt rem eveniet architecto"}
Post {userId = 1, id = 2, title = "qui est esse", body = "est rerum tempore vitae\nsequi sint nihil reprehenderit dolor beatae ea dolores neque\nfugiat blanditiis voluptate porro vel nihil molestiae ut reiciendis\nqui aperiam non debitis possimus qui neque nisi nulla"}
Post {userId = 1, id = 1, title = "sunt aut facere repellat provident occaecati excepturi optio reprehenderit", body = "quia et suscipit\nsuscipit recusandae consequuntur expedita et cum\nreprehenderit molestiae ut ut quas totam\nnostrum rerum est autem sunt rem eveniet architecto"}
{"params":{"userId":101,"title":"test title","body":"test body"},"id":1}
{"params":{"userId":101,"title":"test title","body":"test body"},"id":101}
{}