将AuthGuard服务添加到Angular组件时出错

Question

Trying to add an identity service but it's falling over, the token is received from the API. Any help appreciated.

app.module:

import { AuthGuard } from './auth-guard.service';

@NgModule({
...  providers: [AuthGuard] })

AuthGuardService:

import { JwtHelper } from 'angular2-jwt';
import { Injectable } from '@angular/core';
import { CanActivate, Router } from '@angular/router';

@Injectable()
export class AuthGuard implements CanActivate {
  constructor(private jwtHelper: JwtHelper, private router: Router) {
  }
  canActivate() {
    const token = localStorage.getItem('jwt');

    if (token && !this.jwtHelper.isTokenExpired(token)) {
      return true;
    }
    this.router.navigate(['login']);
    return false;
  }
}

AppRouting:

{ path: 'account', component: AccountComponent, canActivate: [AuthGuard] }

Error:

ERROR Error: Uncaught (in promise): Error: StaticInjectorError(AppModule)[AuthGuard -> JwtHelper]: 
  StaticInjectorError(Platform: core)[AuthGuard -> JwtHelper]: 
    NullInjectorError: No provider for JwtHelper!
Error: StaticInjectorError(AppModule)[AuthGuard -> JwtHelper]: 
  StaticInjectorError(Platform: core)[AuthGuard -> JwtHelper]: 
    NullInjectorError: No provider for JwtHelper!

Answer 1

Please remove injecting JwtHelper in a constructor and create an object for JwtHelper inside of your canActivate like this:

export class AuthGuard implements CanActivate {
  constructor(private router: Router) {
  }
  canActivate() {
    let jwtHelper: JwtHelper = new JwtHelper();

    const token = localStorage.getItem('jwt');

    if (token && !this.jwtHelper.isTokenExpired(token)) {
      return true;
    }
    this.router.navigate(['login']);
    return false;
  }
}