Angular 2 Http 错误

Question

我是 Angular 2 的新手，我非常依赖 HTTP。

应用程序运行但当我尝试获取我的 InMemoryDbService 时它失败了。

错误是：

EXCEPTION: Uncaught (in promise): TypeError: Cannot read property '0' of undefined

但我没有尝试访问“0”属性。当我在 clientes.service.ts

中删除函数 get(this.url) 时错误消失

我的代码：

clientes.service.ts

import { Injectable } from '@angular/core';
import { Cliente } from './../models/clientes';
import { Http } from '@angular/http';
import 'rxjs/add/operator/toPromise';

@Injectable()
export class ClientesService{

    private headers = new Headers({'Content-Type': 'application/json'});
    private url = '/app/components/apis/clientes-data';// URL a la web api.

    constructor(private http: Http) { }

// Método Get para obtener la lista de objetos.
// 
    get(): Promise<Cliente[]> {
        console.log(this.http.get(this.url)); // THE ERROR IS HERE
        return this.http.get(this.url)        // AND HERE IN 
                   .get(this.url)
                   .toPromise()
                   .then(response => response.json().data as Cliente[])
                   .catch(this.handleError);
    }

    private handleError(error: any): Promise<any> {
        console.error('Ha habido un error con la solicitud '+this.url, error);
        return Promise.reject(error.message || error);
    }

}

客户-data.service.ts

import { InMemoryDbService } from 'angular2-in-memory-web-api';
export class ClientesData implements InMemoryDbService {
    createDb() {
        let clientes = [
           { id: '1', nombre: 'Pepe' },
           { id: '2', nombre: 'Juan' },
           { id: '3', nombre: 'Paco' },
           { id: '4', nombre: 'Chema' }
        ];
        return {clientes};
     }
}

app.module.ts

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { HttpModule } from '@angular/http';
import { InMemoryWebApiModule } from 'angular2-in-memory-web-api';

// Imports for loading & configuring the in-memory web api
import { XHRBackend } from '@angular/http';

import './rxjs-extensions';
import { AppComponent } from './app.component';
import { routing } from './app.routing';

/** DATAS SERVICE */
import { ClientesData } from './components/apis/clientes-data.service';

/** PIPES */
import { KeyArrayPipe } from './components/pipes/keyArray.pipe';

import { MainComponent } from './main.component';
import { HeaderComponent } from './header.component';
import { FooterComponent } from './footer.component';
import { NavLeftComponent } from './nav-left.component';
import { DashboardComponent } from './components/dashboard.component';
import { ListadoComponent } from './components/listado.component';

@NgModule({
  imports: [
    BrowserModule,
    FormsModule,
    routing,
    HttpModule,
InMemoryWebApiModule.forRoot(ClientesData),
  ],
  declarations: [
    AppComponent, 
    MainComponent, 
    HeaderComponent, 
    FooterComponent, 
    NavLeftComponent,
    DashboardComponent,
    ListadoComponent,
    KeyArrayPipe
  ],
  providers: [
  ],
  bootstrap: [AppComponent]
})
export class AppModule { }

package.json

{
 "name": "angular2-tour-of-heroes",
 "version": "0.1.0",
 "scripts": {
   "start": "tsc && concurrently \"npm run tsc:w\" \"npm run lite\" ",
   "lite": "lite-server",
   "postinstall": "typings install",
   "tsc": "tsc",
"tsc:w": "tsc -w",
"typings": "typings"
 },
 "dependencies": {
   "@angular/common": "2.0.0-rc.6",
   "@angular/compiler": "2.0.0-rc.6",
   "@angular/compiler-cli": "0.6.0",
   "@angular/core": "2.0.0-rc.6",
   "@angular/forms": "2.0.0-rc.6",
   "@angular/http": "2.0.0-rc.6",
   "@angular/platform-browser": "2.0.0-rc.6",
   "@angular/platform-browser-dynamic": "2.0.0-rc.6",
   "@angular/router": "3.0.0-rc.2",
   "@angular/upgrade": "2.0.0-rc.6",
   "angular2-in-memory-web-api": "0.0.18",
   "concurrently": "^2.2.0",
   "core-js": "^2.4.1",
   "reflect-metadata": "^0.1.3",
   "rxjs": "5.0.0-beta.11",
   "systemjs": "0.19.27",
   "zone.js": "^0.6.17"
 },
 "devDependencies": {
   "concurrently": "^2.2.0",
   "lite-server": "^2.2.2",
   "typescript": "^1.8.10",
   "typings": "^1.3.2"
 }
}

谢谢！！

Answer 1

您尝试获取数据的方式可能没有什么问题，错误可能是因为您没有指向正确的端点，所以没有数据。

如果您没有更改该集合的默认 API 基数（查看文档 here），则意味着您需要将 private url = '/app/components/apis/clientes-data'; 更改为 private url = 'app/clientes-data';
除了第一个更改之外，您需要非常小心集合名称。现在你正试图获取一个不存在的集合。您的集合名为 clientes 而不是 clientesData（这是服务名称）。我建议查看 John Papa 的 example，您可以在其中轻松看出差异。尝试按照这种方式进行操作以使其正常工作。

请尝试将private url = '/app/components/apis/clientes-data';改成private url = '/app/clientes';，看看是否还有错误。

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