Angular - Interceptor not loading in a lazy loaded module

Question

I have created an interceptor which appends a token to the authorization header only needed for API calls made within a feature lazy loaded module.

However, I don't think the interceptor is being called as no console.logs are being displayed when within the reports module.

I have read on other questions that this may have something to do with the HTTPClientModule . This HttpClientModule is only ever once initialized in my main app.module .

How do I get an interceptor to work only for a lazy loaded feature module?

auth.interceptor.ts

import { Injectable } from '@angular/core';
import { HttpInterceptor, HttpHandler, HttpRequest, HttpEvent, HttpResponse } from '@angular/common/http';
import { Observable } from 'rxjs/observable';
import 'rxjs/add/operator/do';

import { AuthService } from './../services/auth/auth.service';

@Injectable()
export class AuthInterceptor implements HttpInterceptor {

    constructor(private auth: AuthService) {
        console.log('start interceptor');
     }

    intercept(req: HttpRequest<any>, next: HttpHandler) {

        console.log('intercepting');

        const authToken = this.auth.getProfileToken();

        console.log(authToken);

        const authReq = req.clone({
            headers: req.headers.set('Authorization', authToken)
        });

        return next.handle(authReq);

    }

}

reports.module.ts

import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { UpperCasePipe } from '@angular/common';
import { DatePipe } from '@angular/common';
import { HTTP_INTERCEPTORS } from '@angular/common/http';

import { ReportsRoutingModule } from './reports-routing.module';

...

import { SharedModule } from './../shared/shared.module';

..

import { AuthInterceptor } from './../core/interceptors/auth.interceptor';

@NgModule({
    imports: [
        CommonModule,
        SharedModule,
        ReportsRoutingModule,
    ],
    declarations: [
        ...
    ],
    entryComponents: [
        ...
    ],
    providers: [DatePipe, UpperCasePipe,
        { provide: HTTP_INTERCEPTORS, useClass: AuthInterceptor, multi: true }
    ]
})
export class ReportsModule { }

app.module.ts

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { BrowserAnimationsModule } from '@angular/platform-browser/animations';

import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';

import { SharedModule } from './shared/shared.module';
import { CoreModule } from './core/core.module';
import { HttpClientModule } from '@angular/common/http';
   
@NgModule({
    declarations: [
        AppComponent
    ],
    imports: [
        BrowserModule,
        AppRoutingModule,
        BrowserAnimationsModule,
        HttpClientModule,
        SharedModule,
        CoreModule.forRoot(),
    ],
    providers: [],
    bootstrap: [AppComponent]
})
export class AppModule { }

app-routing.module.ts

import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';
import { AuthGuard } from '../app/core/guard/auth/auth.guard';

const routes: Routes = [
    {
        path: 'reports',
        loadChildren: './reports/reports.module#ReportsModule',
        canActivate: [
            AuthGuard
        ]
    }
];

@NgModule({
    imports: [RouterModule.forRoot(routes)],
    exports: [RouterModule],
    providers: [AuthGuard]
})
export class AppRoutingModule { }

Answer 1

The HTTP_INTERCEPTORS provider token is reset when a lazy loaded module imports another module which imports the HttpClientModule by itself.

So HttpClientModule can be included in your application module, and is only necessary once.

https://angular.io/guide/http#setup-installing-the-module

Answer 2

Every time a module loads in lazy loaded module a new instance of the HttpClient service is injected in the module that has not been configured to use the interceptor configured in the AppModule . So add interceptors at module level instead of application level.

Answer 3

Import HttpClientModule into your lazy (reports.module.ts) loaded module, then the interceptor will trigger:

...
@NgModule({
    imports: [
        CommonModule,
        SharedModule,
        ReportsRoutingModule,
        HttpClientModule,
    ],
...