The specified type 'Observable<string | null>' cannot be assigned to type 'string'

Question

The specified type 'Observable<string | null>' cannot be assigned to type 'string'

I am struggling with the following code:

id$!: Observable<string | null>;
 characterDetail$!: Observable<CharacterData | undefined>;   //??????

 constructor(
   private router: ActivatedRoute,
   private store$: Store
 ) {} 

 ngOnInit(): void {
   this.id$ = of(this.router.snapshot.paramMap.get('id'));
   this.getCharacterDetail();
   this.characterDetail$ = this.store$.select(charDetailsSelector);
 }

 getCharacterDetail() { 
   if (!this.id$) {
     return;
   }
   this.store$.dispatch(getCharDetailsData({id: this.id$ }));

 }

I encountered an issue in this section: https://i.sstatic.net/tWxgv.png

angular typescript rxjs

Answer 1

Answer №1

The mysterious function known as getCharDetailsData is in need of a string input for id, but instead receives an Observable called this.id$. It appears that what you really need is a BehaviorSubject. Consider using the following code snippet:

getCharacterDetail() { 
   if (!this.id$.value) {
     return;
   }
   this.store$.dispatch(getCharDetailsData({id: this.id$.value }));
 }

Answer 2

The mysterious function known as getCharDetailsData is in need of a string input for id, but instead receives an Observable called this.id$. It appears that what you really need is a BehaviorSubject. Consider using the following code snippet:

getCharacterDetail() { 
   if (!this.id$.value) {
     return;
   }
   this.store$.dispatch(getCharDetailsData({id: this.id$.value }));
 }

Answer 3

Answer №2

Issue One:

Instead of converting id from the router snapshot to an observable in onInit using the 'of' operator, this method only emits one value because the source is a single from the snapshot and is not reactive to changes in the actual route.

Second Issue:

Instead of creating an observable, consider removing it from onInit and implementing something like the following in the getCharacterDetail function:

getCharacterDetail() {
   const id = this.router.snapshot.paramMap.get('id');
   if (!id) {
     return;
   }
   this.store$.dispatch(getCharDetailsData({id: id}));
}

Answer 4

Issue One:

Instead of converting id from the router snapshot to an observable in onInit using the 'of' operator, this method only emits one value because the source is a single from the snapshot and is not reactive to changes in the actual route.

Second Issue:

Instead of creating an observable, consider removing it from onInit and implementing something like the following in the getCharacterDetail function:

getCharacterDetail() {
   const id = this.router.snapshot.paramMap.get('id');
   if (!id) {
     return;
   }
   this.store$.dispatch(getCharDetailsData({id: id}));
}

The specified type 'Observable<string | null>' cannot be assigned to type 'string'

Answer №1

Answer №2

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