Angular 6 - 无法解析AppComponent的所有参数

Question

我正在尝试使用Angular 6构建一个应用程序,我仍在设置所有内容.但似乎我的应用程序中的依赖注入有问题.

它无法解析任何构造函数参数.他们都导致了Uncaught Error: Can't resolve all parameters for AppComponent: (?)..即使是自定义服务也会导致相同的错误.

版本 (省略了对此不会产生任何影响的依赖项)

 "dependencies": {
    "@angular/common": "6.0.5",
    "@angular/compiler": "6.0.5",
    "@angular/core": "6.0.5",
    "@angular/forms": "6.0.5",
    "@angular/http": "6.0.5",
    "@angular/platform-browser": "6.0.5",
    "@angular/platform-browser-dynamic": "6.0.5",
    "@angular/router": "6.0.5",
    "core-js": "2.5.7",
    "reflect-metadata": "0.1.12",
    "rxjs": "6.2.1",
    "zone.js": "0.8.26"
  },
  "devDependencies": {
    "@angular/compiler-cli": "6.0.5",
    "@ngtools/webpack": "6.0.8",
    "angular2-template-loader": "0.6.2",
    "awesome-typescript-loader": "5.1.0",
    "typescript": "2.7.2",
    "webpack": "4.12.0",
    "webpack-cli": "3.0.8",
    "webpack-dev-server": "3.1.4",
  }

---

app.module.ts

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule {
}

---

TestService.ts

import {Injectable} from "@angular/core";

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

  constructor() {
    console.warn("It works!");
  }

  public sayHello(): string {
    return "hello world!";
  }
}

---

App.component.ts

import {Component} from '@angular/core';
import {TestService} from "./TestService";

@Component({
  selector: 'sh-home',
  styleUrls: ['./home.scss'],
  templateUrl: './home.html'
})
export class HomeComponent {

  constructor(testService: TestService) {
    testService.sayHello();
  }
}

TestService在这种情况下,注入会产生错误

---

Main.ts

import {enableProdMode} from '@angular/core';
import {platformBrowserDynamic} from '@angular/platform-browser-dynamic';

import {AppModule} from './app/app.module';
import './assets/scss/styles.global.scss'; // Import the global scss files

// Polyfills
import './Polyfills';

if (process.env.NODE_ENV === 'production') {
    enableProdMode();
}

platformBrowserDynamic().bootstrapModule(AppModule);

---

Polyfills.ts

/** IE9, IE10 and IE11 requires all of the following polyfills. **/
import 'core-js/es6/symbol';
import 'core-js/es6/object';
import 'core-js/es6/function';
import 'core-js/es6/parse-int';
import 'core-js/es6/parse-float';
import 'core-js/es6/number';
import 'core-js/es6/math';
import 'core-js/es6/string';
import 'core-js/es6/date';
import 'core-js/es6/array';
import 'core-js/es6/regexp';
import 'core-js/es6/map';
import 'core-js/es6/weak-map';
import 'core-js/es6/set';

/** IE10 and IE11 requires the following for NgClass support on SVG elements */
import 'classlist.js';  // Run `npm install --save classlist.js`.

/** IE10 and IE11 requires the following for the Reflect API. */
import 'core-js/es6/reflect';


/** Evergreen browsers require these. **/
// Used for reflect-metadata in JIT. If you use AOT (and only Angular decorators), you can remove.
import 'core-js/es7/reflect';

/***************************************************************************************************
 * Zone JS is required by default for Angular itself.
 */
import 'zone.js/dist/zone';  // Included with Angular CLI.

我没有使用CLI,而是使用自定义启动器.我包括所有与Angular-CLI相同的polyfill,所以我没有错过任何.

有谁看到我做错了什么？

---

更新

我简化了测试用例并注意到它不是翻译模块.即使我创建一个简单的服务,我也不能使用依赖注入.将服务添加到providers列表也不起作用(也不应该是必需的,因为我使用的是Angular 6' provideIn: root').

Answer 1

确保你在polyfills
导入'core-js/es7/reflect'中有以下导入 ;

Answer 2

我也遇到了这个问题，但是在 tsconfig 中设置emitDecoratorMetadata": true可以解决这个问题。记得重启服务器。

tsconfig.spec.json

   "compilerOptions": {
    "emitDecoratorMetadata": true,
     "outDir": "./out-tsc/spec",
   }

Answer 3

我通过重新启动应用程序解决了这个错误。再次构建并运行它，它对我来说很好用。请检查并告诉我。

谢谢 ：）