Angular - Lazy loading a module inside module with a child route

Question

I have an angular application where my main routing module lazy loads modules correctly. I do however now have an additional requirement of displaying another component / module inside one of the lazy loaded modules.

When I now navigate to users/id (this part works correctly) I want a tab view in the HTML where I can load additional modules based on what tab is clicked on. For example, I might have 3 buttons: User Albums, User Favourites and User Stats. When I click on one of those, I want a component to display on the same page as a child using the <router-outlet></router-outlet>

App Routing Module

import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';

const routes: Routes = [
  { path: 'login',                 loadChildren: '../app/login/login.module#LoginModule' },
  { path: 'users',                 loadChildren: '../app/users/users.module#UsersModule' },
  { path: 'users/:id',             loadChildren: '../app/user-detail/user-detail.module#UserDetailModule' },
  { path: '',                      loadChildren: '../app/login/login.module#LoginModule', pathMatch: 'full' },
  { path: '**',                    loadChildren: '../app/login/login.module#LoginModule', pathMatch: 'full' },
];

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

user-detail.module

import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { UserDetailComponent } from './user-detail.component';
import { Routes, RouterModule } from '@angular/router';

const routes: Routes = [
  {
    path: '',
    component: UserDetailComponent,
    children: [
      {
        path: 'useralbums',
        loadChildren: '../user-albums/user-albums.module#UserAlbumsModule'
      },
    ]
  },
]


@NgModule({
  imports: [
    CommonModule,
    RouterModule.forChild(routes),
  ],
  declarations: [UserDetailComponent]
})
export class UserDetailModule { }

user-detail.html

<h1>User Detail</h1>
<a [routerLink]="['/users', user_id, 'useralbums']">User albums</a>
<a>Link Two</a>
<a>Link Three</a>
<router-outlet></router-outlet>

Answer 1

Since you want a new component to be loaded in case of a child route change and load it as a part of a lazy-loaded module, you can add a <router-outlet></router-outlet> to the template of the user-detail.component.html.

Something like this:

<h1>User Detail</h1>
<ul class="nav">
  <li class="nav-item">
    <a [routerLink]="['/users', user_id, 'user-albums']">User Albums</a>
  </li>
  <li class="nav-item">
    <a [routerLink]="['/users', user_id, 'user-favourites']">User Favourites</a>
  </li>
  <li class="nav-item">
    <a [routerLink]="['/users', user_id, 'user-stats']">User Stats</a>
  </li>
</ul>
<router-outlet></router-outlet>

Now, in the module of this file, define a route configuration to load the respective modules lazily:

import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { Routes, RouterModule } from '@angular/router';

import { UserDetailComponent } from './user-detail.component';

const routes: Routes = [
  { 
    path: '', 
    component: UserDetailComponent,
    children: [
      {
        path: 'user-albums',
        loadChildren: './user-albums/user-albums.module#UserAlbumsModule'
      },
      {
        path: 'user-favourites',
        loadChildren: './user-favourites/user-favourites.module#UserFavouritesModule'
      },
      {
        path: 'user-stats',
        loadChildren: './user-stats/user-stats.module#UserStatsModule'
      },
    ]
  }
];

@NgModule({
  imports: [
    CommonModule,
    RouterModule.forChild(routes)
  ],
  declarations: [UserDetailComponent]
})
export class UserDetailModule { }

And then define the lazy modules with their configuration like this:

import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { Routes, RouterModule } from '@angular/router';

import { UserAlbumsComponent } from './user-albums.component';

const routes: Routes = [
  { path: '**', component: UserAlbumsComponent }
];

@NgModule({
  imports: [
    CommonModule,
    RouterModule.forChild(routes)
  ],
  declarations: [UserAlbumsComponent]
})
export class UserAlbumsModule { }

PS: Since there are a lot of components, I'd suggest that you have a look at the solution stackblitz carefully in order to understand how the routing is wired in.

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Here's a Working Sample StackBlitz for your ref.