Check to see if a name is present in the URL using Angular2

Question

Check to see if a name is present in the URL using Angular2

I'm still in the process of learning angular and typescript, so please forgive me for this question that may seem silly...

Currently, I have a list containing actors. When one of these actors is clicked on, it redirects to a detailed page with a URL structure like this:

localhost:4200/actors

After clicking on an actor, the URL changes to something like:

localhost:4200/actors/Jonas

Now, my goal is to verify if the chosen actor actually exists. If a user manually enters a random name in the URL, I want to redirect them back to the /actors page instead of displaying a blank page.

This is a snippet of how my component looks:

actor: Actor;
constructor(
    private actorService: ActorService,
    private route: ActivatedRoute,
    private location: Location
) {}
ngOnInit(): void {
    this.route.params.subscribe(() => {
        if (/* code to check if actor.name exists in the url */) {
            this.route.paramMap.switchMap((params: ParamMap) =>
                this.actorService.getActor(params.get('name')!))
                .subscribe(actor => this.actor = actor);
        } else {
            this.location.go('/actors');
        }
    });
}

Does anyone have any insights on how I can accomplish this?

angular typescript angular-cli

Answer 1

Answer №1

It's not recommended to nest the subscribe call. A more efficient approach would be using mergeMap or switchMap for handling nested asynchronous operations.

One way to retrieve the name parameter from the route path is shown below:

constructor(private router: Router,
           private actorService: ActorService,
           private route: ActivatedRoute,
           private location: Location)
{}
ngOnInit(): void {
    this.route.params
    .mergeMap(
       (params: Params) => {
          if(params['name']) {
             return this.actorService.getActor(param['name']);
          } 
          return Observable.of(false);
       }
    )
      .subscribe((actor: any) => {
        if (actor ) {
             this.actor = actor;
        }else {
            this.router.navigate(['/actors']);
        }
    });
}

Answer 2

It's not recommended to nest the subscribe call. A more efficient approach would be using mergeMap or switchMap for handling nested asynchronous operations.

One way to retrieve the name parameter from the route path is shown below:

constructor(private router: Router,
           private actorService: ActorService,
           private route: ActivatedRoute,
           private location: Location)
{}
ngOnInit(): void {
    this.route.params
    .mergeMap(
       (params: Params) => {
          if(params['name']) {
             return this.actorService.getActor(param['name']);
          } 
          return Observable.of(false);
       }
    )
      .subscribe((actor: any) => {
        if (actor ) {
             this.actor = actor;
        }else {
            this.router.navigate(['/actors']);
        }
    });
}

Answer 3

Answer №2

When using Angular, you can leverage a feature called Resolver to fetch data before navigating to a specific route. A Resolver is essentially a service that implements the Resolve interface from @angular/router.

For instance, you can create a Resolver like this for handling actors:

@Injectable()
export class ActorResolver implements Resolve<Actor> {
  constructor(private actorService: ActorService, private router: Router) {}

  resolve(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): Observable<Actor> {
    let name = route.paramMap.get('name');
    return this.actorService.getActor(name).pipe(take(1)).map(actor => {
      if(actor) { // check if actor exists else redirect
        return actor;
      } else {
        this.router.navigate(['/actors']);
        return null;
      }
    });
  }
}

To use the Resolver, make sure to add it to the providers list in the module file and specify it in the route configuration:

{ 
  path: ':name',
  component: ActorDetailsComponent,
  resolve: {
    actor: ActorResolver
  }}
}

In your component, you can access the resolved data like this:

constructor(private route: ActivatedRouteSnapshot) {
  this.actor = this.route.data.actor;
}

For more information on route resolvers, refer to the official documentation.

Answer 4

When using Angular, you can leverage a feature called Resolver to fetch data before navigating to a specific route. A Resolver is essentially a service that implements the Resolve interface from @angular/router.

For instance, you can create a Resolver like this for handling actors:

@Injectable()
export class ActorResolver implements Resolve<Actor> {
  constructor(private actorService: ActorService, private router: Router) {}

  resolve(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): Observable<Actor> {
    let name = route.paramMap.get('name');
    return this.actorService.getActor(name).pipe(take(1)).map(actor => {
      if(actor) { // check if actor exists else redirect
        return actor;
      } else {
        this.router.navigate(['/actors']);
        return null;
      }
    });
  }
}

To use the Resolver, make sure to add it to the providers list in the module file and specify it in the route configuration:

{ 
  path: ':name',
  component: ActorDetailsComponent,
  resolve: {
    actor: ActorResolver
  }}
}

In your component, you can access the resolved data like this:

constructor(private route: ActivatedRouteSnapshot) {
  this.actor = this.route.data.actor;
}

For more information on route resolvers, refer to the official documentation.

Answer 5

Answer №3

Give this a shot

this.route.params.subscribe( param => {
            //verify if there is a value in the name parameter
        if (param['name') {
            // retrieve the data
              this.actorService.getActor(param['name'])
              .then( actor =>{
                    //if the data does not exist, redirect to /actors
                   if(!actor)
                     this.location.go('/actors');
               })
        }else {
            this.location.go('/actors');
        }
    });

Answer 6

Give this a shot

this.route.params.subscribe( param => {
            //verify if there is a value in the name parameter
        if (param['name') {
            // retrieve the data
              this.actorService.getActor(param['name'])
              .then( actor =>{
                    //if the data does not exist, redirect to /actors
                   if(!actor)
                     this.location.go('/actors');
               })
        }else {
            this.location.go('/actors');
        }
    });

Answer 7

Answer №4

//below is the script

this.route.params.subscribe( params => {
        if (params['name']) {
           //place your code here
        }else {
            this.location.go('/actors');
        }
    });

Answer 8

//below is the script

this.route.params.subscribe( params => {
        if (params['name']) {
           //place your code here
        }else {
            this.location.go('/actors');
        }
    });

Answer 9

Answer №5

character: Character;
constructor(
    private characterService: CharacterService,
    private route: ActivatedRoute,
    private location: Location
) {}
ngOnInit(): void {
    this.route.params.subscribe((params) => {
        if (params['name']) {
            this.characterService.getCharacter(params.get('name')!))
                .subscribe(character => this.character = character);
        }else {
            this.location.go('/characters');
        }
    });
}

Answer 10

character: Character;
constructor(
    private characterService: CharacterService,
    private route: ActivatedRoute,
    private location: Location
) {}
ngOnInit(): void {
    this.route.params.subscribe((params) => {
        if (params['name']) {
            this.characterService.getCharacter(params.get('name')!))
                .subscribe(character => this.character = character);
        }else {
            this.location.go('/characters');
        }
    });
}

Check to see if a name is present in the URL using Angular2

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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