Angular 5开发遇StaticInjectorError：Vtos无提供者求助

Hey, let's sort out this dependency injection error you're running into! That NullInjectorError means Angular can't find a registered provider for your Vtos service when it tries to inject it into VtoReportComponent. Let's walk through the fixes step by step.

Step 1: Fix Your Service's Decorator #

Looking at your vto.service.ts snippet, you imported Component instead of the required Injectable decorator—this is a critical mix-up. Services need the @Injectable() decorator to tell Angular they're meant to be injected into other components/services. Here's the corrected start of your service file:

import { Injectable } from '@angular/core';
import { Http, HttpModule } from '@angular/http';
import { Observable } from 'rxjs/Observable';

@Injectable()
export class Vtos {
  constructor(private http: Http) {}
  
  // Your service methods and logic go here
}

Step 2: Register the Service in AppModule #

Since you're using Angular 5 (which doesn't support the providedIn: 'root' syntax added in Angular 6), you need to explicitly add your Vtos service to the providers array in your AppModule to make it available across your app:

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { HttpModule } from '@angular/http';
import { Vtos } from './path/to/vto.service'; // Update this to your actual service file path
import { VtoReportComponent } from './path/to/vto-report.component'; // Your component path

@NgModule({
  declarations: [
    VtoReportComponent
    // Add other components/directives/pipes here
  ],
  imports: [
    BrowserModule,
    HttpModule
    // Add other imported modules here
  ],
  providers: [
    Vtos // Register your service here
  ],
  bootstrap: [/* Your root component (e.g., AppComponent) */]
})
export class AppModule { }

Step 3: Double-Check Component Injection #

Make sure you're correctly injecting the Vtos service in VtoReportComponent's constructor, with the right import path:

import { Component, OnInit } from '@angular/core';
import { Vtos } from './path/to/vto.service'; // Confirm this path matches your service location

@Component({
  selector: 'app-vto-report',
  templateUrl: './vto-report.component.html'
})
export class VtoReportComponent implements OnInit {
  constructor(private vtosService: Vtos) { } // Correct injection syntax

  ngOnInit() {
    // Use your service here, e.g. this.vtosService.yourMethod()
  }
}

Quick Notes for Your Environment #

• Since you're working with .NET Core 2.0 in Visual Studio 2017 15.6.7, double-check that all import paths in your Angular code match the actual file structure (no typos or wrong folder references).
• For RxJS 5.5.10, if you use operators like map or subscribe in your service, make sure you import them correctly (e.g., import 'rxjs/add/operator/map';).

内容的提问来源于stack exchange，提问作者SilverFish