如何将 Angular2 Http 服务注入 es6/7 Class？

Question

如果我使用 es6/7（babel - 第 1 阶段）而不是 TypeScript，如何注入服务，特别是 Http？

这是我的组件 JS：

import {Component, Inject, View, CORE_DIRECTIVES, ViewEncapsulation} from 'angular2/angular2';
import {Http} from 'angular2/http';

@Component({
  selector: 'login'
})
@View({
  templateUrl: './components/login/login.html',
  styleUrls: ['components/login/login.css'],
  directives: [CORE_DIRECTIVES],
  encapsulation: ViewEncapsulation.Emulated
})
export class Login {
  constructor(@Inject(Http) http) {
    console.log('http', http);
  }

  authenticate(username, password) {
    // this.http.get('/login');
  }
}

我试过：

export class Login {
  constructor(@Inject(Http) http) {
    console.log('http', http);
  }
}
/********************/
@Inject(Http)
export class Login {
  constructor(http) {
    console.log('http', http);
  }
}
/********************/
export class Login {
  constructor(Http: http) {
    console.log('http', http);
  }
}
/********************/
export class Login {
  constructor(http = Http) {
    console.log('http', http);
  }
}
/********************/
export class Login {
  constructor(Http) {
    this.http = new Http()
    console.log('http', this.http);
  }
}
/********************/
export class Login {
  constructor(http = new Http()) {
    console.log('http', http);
  }
}

除第一个之外的所有编译。其他人允许我访问 Http class 或 http 实例。但是 none 有效。

我试图关注 Eric Martinez 在他的评论中引用的讨论。 Login.js 现在：

import {Component, Inject, View, CORE_DIRECTIVES, ViewEncapsulation} from 'angular2/angular2';
import {HTTP_BINDINGS, Http, BaseRequestOptions, RequestOptions, RequestMethods} from 'angular2/http';

@Component({
  selector: 'login'
})
@View({
  templateUrl: './components/login/login.html',
  styleUrls: ['components/login/login.css'],
  directives: [CORE_DIRECTIVES],
  encapsulation: ViewEncapsulation.Emulated,
  bindings: [Http]
})
export class Login {

  constructor(http) {
    this.http = http;
    console.log('http', http);
  }

  authenticate(usernameEl, passwordEl) {
    var username = usernameEl.value;
    var password = passwordEl.value;
    console.log('username', username, password);

    // this.http.get('/login');
  }
}

Login.parameters = [Http];

它现在编译但产生以下错误：

Uncaught (in promise) NoBindingError {message: "No provider for Http! (Login -> Http)", stack: "Error: DI Exception↵ at NoBindingError.BaseExce…or._new (http://localhost:3000/bundle.js:7319:22)", keys: Array[2], injectors: Array[2]}constructResolvingMessage: (keys)arguments: (...)caller: (...)length: 1name: ""prototype: Object__proto__: ()context: (...)injectors: Array[2]0: Injector1: Injectorlength: 2__proto__: Array[0]keys: Array[2]message: "No provider for Http! (Login -> Http)"stack: "Error: DI Exception↵ at NoBindingError.BaseException [as constructor] (http://localhost:3000/bundle.js:8400:24)↵ at NoBindingError.AbstractBindingError [as constructor] (http://localhost:3000/bundle.js:9066:17)↵ at new NoBindingError (http://localhost:3000/bundle.js:9102:17)↵ at Injector._throwOrNull (http://localhost:3000/bundle.js:7469:20)↵ at Injector._getByKeyDefault (http://localhost:3000/bundle.js:7516:22)↵
at Injector._getByKey (http://localhost:3000/bundle.js:7461:26)↵ at Injector._getByDependency (http://localhost:3000/bundle.js:7447:26)↵
at Injector._instantiate (http://localhost:3000/bundle.js:7339:37)↵
at Injector._instantiateBinding (http://localhost:3000/bundle.js:7330:26)↵ at Injector._new (http://localhost:3000/bundle.js:7319:22)"proto: __

Answer 1

我已经回答了，如果你用ES7写代码，使用static getter for parameters 属性指定注入constructor 你的组件。例如：

import { Http } from 'angular2/http';
// other imports ...

// component decorators ...
export class Login {

  static get parameters() {
    return [[Http]];
  }

  constructor(http) {
    this.http = http;
    console.log('http', http);
  }

  // other methods
}

我认为这是目前最简洁的方法。

请记住，目前还没有在 ES7 中支持参数装饰器的提案（例如 see this issue for Babel）。

Answer 2

官方API Review的方法对我有用：

import {Http, HTTP_PROVIDERS} from 'angular2/http';
@Component({
  selector: 'http-app',
  viewProviders: [HTTP_PROVIDERS],
  templateUrl: 'people.html'
})
class PeopleComponent {
  constructor(http: Http) {
    http.get('people.json')
      .map(res => res.json())
      .subscribe(people => this.people = people);
  }
}

Answer 3

因为您在 Babel 中启用了 @Decorators

...我将 fine-tune 这个答案与您的特定设置一起使用。

1.你错过了 HTTP_PROVIDERS

HTTP_PROVIDERS 常量包括处理 HTTP requests/responses 所需的许多函数。

import {Http, HTTP_PROVIDERS} from 'angular2/http';    

@Component({
  selector: 'login',
  providers: [ HTTP_PROVIDERS ]
})

2。您需要对 DI（依赖注入）语法进行脱糖

如所述。

删除静态类型

constructor(http) {

@Inject 隐式处理 DI 但仅在 Angular2+Typescript 中受支持。由于您使用的是 Angular2+ES6，因此您需要将静态 getter 参数附加到您的 class 以提供特定于 ES6 的等价物。

static get parameters() {
    return [[Http]];
}

3。您需要将 Http 实例绑定到构造函数中的 class

通过这样做，它将可以在您的 authenticate() 方法中访问。

constructor(http) {
    this.http = http;
    console.log('http', this.http);
}

...以及完整的实现：

import {Component, Inject, View, CORE_DIRECTIVES, ViewEncapsulation} from 'angular2/angular2';
import {Http, HTTP_PROVIDERS} from 'angular2/http';

@Component({
  selector: 'login',
  // required for Http
  providers: [ HTTP_PROVIDERS ]
})
@View({
  templateUrl: './components/login/login.html',
  styleUrls: ['components/login/login.css'],
  directives: [CORE_DIRECTIVES],
  encapsulation: ViewEncapsulation.Emulated
})
export class Login {
  constructor(http) {
    // bind http to your class during construction
    //   so it's available to authenticate()
    this.http = http;
  }

  // Angular2 DI desugar'd
  static get parameters() {
    return [[Http]];
  }

  authenticate(username, password) {
    this.http.get('/login');
  }
}

旁白：我知道这是有效的，因为我将它用于 EvanPlaice.com.

上的 <ng2-markdown> 组件

Answer 4

使用 babel-plugin-angular2-annotations，您可以像 TypeScript 一样使用构造函数参数类型注释注入服务。

安装 babel 插件：

npm install -D babel-plugin-angular2-annotations babel-plugin-transform-decorators-legacy babel-plugin-transform-class-properties babel-plugin-transform-flow-strip-types babel-preset-es2015

.babelrc:

{
  "plugins": [
    "angular2-annotations",
    "transform-decorators-legacy",
    "transform-class-properties",
    "transform-flow-strip-types"
  ],
  "presets": [
    "es2015"
  ]
}

瞧！

import {Component, View, CORE_DIRECTIVES, ViewEncapsulation} from 'angular2/angular2';
import {Http} from 'angular2/http';

@Component({
  selector: 'login'
})
@View({
  templateUrl: './components/login/login.html',
  styleUrls: ['components/login/login.css'],
  directives: [CORE_DIRECTIVES],
  encapsulation: ViewEncapsulation.Emulated
})
export class Login {
  constructor(http: Http) {
    console.log('http', http);
    this.http = http;
  }

  authenticate(username, password) {
    this.http.get('/login');
  }
}

请注意，类型签名仅用于依赖注入的提示，不用于类型检查。

如何将 Angular2 Http 服务注入 es6/7 Class？

How to Inject Angular2 Http service into es6/7 Class?

javascript

babeljs

angular