I am trying to build an application with Angular 6 and I am still setting everything up. But it seems there is something wrong with the dependency injection in my app.
It cannot resolve any constructor parameter. They all result in Uncaught Error: Can't resolve all parameters for AppComponent: (?).
. Even a custom service results in the same error.
Versions (omitted the dependencies that can't have any influence on this)
"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();
}
}
The injection of the TestService
gives the error in this case
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.
I am not using the CLI, but a custom starter. I included all the same polyfills as Angular-CLI does, so I am not missing any.
Does anyone see what I am doing wrong?
Update
I've simplified the test case and noticed that it is not the translation module. Even if I create a simple service I cannot use dependency injection. Adding the service to the providers
list doesn't work either (and also shouldn't be necessary, since I am using the Angular 6 'provideIn: root
').
Make sure you have following import in polyfills:
import 'core-js/es7/reflect';
I also got this issue but setting emitDecoratorMetadata": true in tsconfig solve the issue. Remember to restart the server.
tsconfig.spec.json
"compilerOptions": {
"emitDecoratorMetadata": true,
"outDir": "./out-tsc/spec",
}
I resolved this error by just restarting app. build it again and run it, it's works fine for me. Please check and tell me.
Thanks :)
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