Angular Router: Defining Child Routes

It’s easy to create any kind of routing hierarchy in your Angular apps by using child routes in your router configurations.

All you need to define child routes is to add an array of additional route configuration objects as part of a children key in your parent configuration. Here’s an example configuration:

const routes: Routes = [
  { path: '', component: ParentComponent, children: [
    { path: 'red', component: ChildComponent },
    { path: 'blue', component: AnotherChildComponent }
  ] }
];

And don’t forget to add a router-outlet directive in the template of any parent component:

<router-outlet></router-outlet>

We such configuration, the available routes will be /, /red and /blue (e.g: http://localhost:4200/red)

Child routes can in turn also have child routes of their own:

const routes: Routes = [
  { path: '', component: ParentComponent, children: [
    { path: 'red', component: ChildComponent, children: [
      { path: 'knock-knock', component: SubChildComponent, children: [
        { path: 'neo', component: SubSubChildComponent }
      ] },
    ] },
    { path: 'blue', component: AnotherChildComponent }
  ] }
];

And now you’ll be able to go to the end of the rabbit hole by navigating to /red/knock-knock/neo 🐇

Routes Without Paths

You don’t have to necessarily have paths to all your routes. Let’s take this variation on the previous configuration for example:

const routes: Routes = [
  { path: '', component: ParentComponent, children: [
    { path: '', component: ChildComponent, children: [
      { path: 'knock-knock', component: SubChildComponent, children: [
        { path: 'neo', component: SubSubChildComponent }
      ] },
    ] },
    { path: 'blue', component: AnotherChildComponent }
  ] }
];

Notice how the route with the ChildComponent component doesn’t have a path. This means that the user will navigate directly to /knock-knock/neo, but ChildComponent will still be instantiated and its children will still be inserted into its router outlet.

Componentless Routes

It’s also possible to have a parent route that has no component:

const routes: Routes = [
  { path: '', component: ParentComponent, children: [
    { path: 'red', children: [
      { path: 'knock-knock', component: SubChildComponent, children: [
        { path: 'neo', component: SubSubChildComponent }
      ] },
    ] },
    { path: 'blue', component: AnotherChildComponent }
  ] }
];

With this configuration, the user can still navigate to /red/knock-knock/neo, but the SubChildComponent will be inserted in the ParentComponent’s router outlet instead.

This can be useful if our path provides us with data or params that we want available in in the rest of the chain of components or in sibling components. Let’s illustrate with an example:

const routes: Routes = [
  { path: '', component: ParentComponent, children: [
    { path: ':choice', children: [
      { path: 'neo', component: ChildComponent },
      { path: 'trinity', component: AnotherChildComponent }
    ] }
  ] }
];

With this configuration, both ChildComponent and AnotherChildComponent will have access to the choice param, and we didn’t have to involve another dummy component just to wrap both siblings.