代码之家 › 专栏 › 技术社区 › Gonçalo Peres

StaticInjectorError-填充下拉列表

angular6 asp.net-core api angular

Gonçalo Peres · 技术社区 · 5 年前

角型V6.1.10_ASP.NET核心V2.2.102

我正试图从我的API中提取数据来填充我的Angular应用程序的下拉列表。

我在控制台上收到以下错误和警告:

警告

WebSocket连接到 'ws://localhost:5000/sockjs node/050/xwusnroj/websocket'失败: WebSocket在建立连接之前关闭。 websockettransport.close@sockjs.js:2998

误差

错误错误:未捕获(承诺中):错误: StaticInjectorError(AppModule)[端口服务->http]:
StaticInjectorError(平台:核心)[portoseService->http]: NullInjectorError:没有HTTP提供程序!

如下图所示:

在运行Karma调试器时,我得到以下规范列表:

反成分应显示标题应以计数0开头, 然后单击FishFormComponent时增量为1 应创建portoseservice

我不确定为什么会出现这些错误。感谢您的帮助!

服务

端口O.services.ts

import { Injectable } from '@angular/core';
import { Http } from '@angular/http';
import { map } from 'rxjs/operators';

@Injectable({
  providedIn: 'root'
})
export class PortoService {

  constructor(private http: Http) { }

  getPortos() {
    return this.http.get('/api/portos')
      .map(res => res.json());
  }
}

应用程序

App.M.模块

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { HttpClientModule } from '@angular/common/http';
import { RouterModule } from '@angular/router';
import { AppComponent } from './app.component';
import { NavMenuComponent } from './nav-menu/nav-menu.component';
import { HomeComponent } from './home/home.component';
import { CounterComponent } from './counter/counter.component';
import { FetchDataComponent } from './fetch-data/fetch-data.component';
import { FishFormComponent } from './fish-form/fish-form.component';
import { PortoService } from './services/porto.service';

@NgModule({
  declarations: [
    AppComponent,
    NavMenuComponent,
    HomeComponent,
    CounterComponent,
    FetchDataComponent,
    FishFormComponent
  ],
  imports: [
    BrowserModule.withServerTransition({ appId: 'ng-cli-universal' }),
    HttpClientModule,
    FormsModule,
    RouterModule.forRoot([
      { path: '', component: HomeComponent, pathMatch: 'full' },
      {path: 'fishes/new', component: FishFormComponent},
      { path: 'counter', component: CounterComponent },
      { path: 'fetch-data', component: FetchDataComponent },
    ])
  ],
  providers: [
    { provide: 'ORIGIN_URL', useValue: location.origin },
    PortoService
  ],
  bootstrap: [AppComponent]
})
export class AppModule { }

形式

鱼形构件.ts

import { PortoService } from './../services/porto.service';
import { Component, OnInit } from '@angular/core';

@Component({
  selector: 'app-fish-form',
  templateUrl: './fish-form.component.html',
  styleUrls: ['./fish-form.component.css']
})
export class FishFormComponent implements OnInit {
  portos;

  constructor(private PortoService: PortoService) { }

  ngOnInit() {
    this.PortoService.getPortos().subscribe(portos => {
      this.portos = portos;
      console.log("PORTOS", this.portos);
    });
  }

}

鱼形构件

<h1>Adiciona um Peixe Novo</h1>
<form>
  <div class="form-group">
    <label for="porto">Porto</label>
    <select id="porto" class="form-control">
      <option value=""></option>
      <option *ngFor="let p of portos" value="{{ p.id }}">{{ p.nome }}</option>
    </select>
  </div>
  <div class="form-group">
    <label for="especie">Especie</label>
    <select id="especie" class="form-control"></select>
  </div>
</form>

1 回复 | 直到 5 年前

Gonçalo Peres 5 年前

通过将porto.services.ts中的导入更新为 @ABOS 建议:

import { HttpClient } from '@angular/common/http';

变化:

constructor(private http: Http)

到

constructor(private http: HttpClient)

作为 HttpClient.get() 应用 res.json() 自动返回 Observable<HttpResponse<string>> ,我已经搬走了 .map(res => res.json()); 因为不需要使用map方法。