How can you establish the default value for a form from an Observable?

Question

How can you establish the default value for a form from an Observable?

Check out my TypeScript component below

export interface Product{
    id?:string,
    name:string,
    price:string;
    quantity:string;
    tags:Tags[];
    description:string;
    files: File[];
}

product$:Observable<Product | undefined>;

ngOnInit(): void { 
  this.store.dispatch(new productActions.LoadProduct(fromProduct.getCurrentProductId.toString()));
  this.product$ = this.store.pipe(select(fromProduct.getCurrentProduct));
}

The last two statements retrieve the value of the product observable and function properly.

this.product = this.fb.group({
    name:['',[
      Validators.required,
      Validators.minLength(1),
      Validators.maxLength(128)
    ]],
    price:['',
    Validators.required],
    tags:this.fb.array(this.tags),
    quantity:['',Validators.required],
    description:['',
    Validators.required]
  });
}

My current aim is to set the default Form values from Product$ (observable)

In the above code, the default value for name is set to ''. However, I would like to set a default value from (product$ | async).name----->> This functionality works correctly in HTML, but I am unsure how to implement it in TypeScript.

Thank you for your assistance.

angular typescript observable angular-reactive-forms

Answer 1

Answer №1

To ensure your FormGroup initialization is executed only once and then unsubscribed, consider placing it within a subscribe function. Remember to include the first operator in order to achieve this.

this.product$
    .pipe(first())
    .subscribe(product => {
        this.product = this.fb.group({
            name:[product.name,[
              Validators.required,
              Validators.minLength(1),
              Validators.maxLength(128)
            ]],
            price:['',
            Validators.required],
            tags:this.fb.array(this.tags),
            quantity:['',Validators.required],
            description:['',
            Validators.required]
          });
        }
    });

Answer 2

To ensure your FormGroup initialization is executed only once and then unsubscribed, consider placing it within a subscribe function. Remember to include the first operator in order to achieve this.

this.product$
    .pipe(first())
    .subscribe(product => {
        this.product = this.fb.group({
            name:[product.name,[
              Validators.required,
              Validators.minLength(1),
              Validators.maxLength(128)
            ]],
            price:['',
            Validators.required],
            tags:this.fb.array(this.tags),
            quantity:['',Validators.required],
            description:['',
            Validators.required]
          });
        }
    });

Answer 3

Answer №2

To ensure you can access any passed values, it is important to subscribe to the observable. Here's an example of how you can achieve this:

const data$ = this.dataService.getDataObservable();
data$.subscribe(data => {
  // Do something with the received data
});

Answer 4

To ensure you can access any passed values, it is important to subscribe to the observable. Here's an example of how you can achieve this:

const data$ = this.dataService.getDataObservable();
data$.subscribe(data => {
  // Do something with the received data
});

How can you establish the default value for a form from an Observable?

Answer №1

Answer №2

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