CODEWITHSUNDEEP
angulartypescriptserviceangular5observable
Ignacio Mariano Chiodo
Ignacio Mariano Chiodo

Reputation: 23

How to return boolean value from a function that subscribes to an observable of another function?

I'm having this problem, I have a ProductService that has a boolean function validateProductsBeforeChanges.

Inside validateProductsBeforeChanges I call a function from another service called OrderService which returns an observable.

Some example code:

validateProductsBeforeChanges(idProduct): Boolean {
     this._orderService.getAll()
         .subscribe(orders => {
               this.orders = orders;
               this.ordersWithCurrentMenu = this.orders.filter(x => 
                                                               x.products.find(y => y.code == idProduct));

               if(this.ordersWithCurrentMenu.length > 0) {
                   return false;
               }
               else {
                   return true;
               }
         });
}

The problem is that vs code throws a syntax error:

A function whose declared type is neither 'void' nor 'any' must return a value

So I tried doing something like this:

validateProductsBeforeChanges(idProduct): Boolean {
     this._orderService.getAll()
         .subscribe(orders => {
              this.orders = orders;
              this.ordersWithCurrentMenu = this.orders.filter(x => x.products.find(y => y.code == idProduct));

              if (this.ordersWithCurrentMenu.length > 0) {
                  return false;
              }
              else {
                  return true;
              }
         });

    return false;
}

But in that case, the last return gets executed before the .subcribe ends and the function always returns false.

Any ideas on how to solve this?

Thank you very much!

Upvotes: 1

Views: 3546

Answers (1)

Michael Kang
Michael Kang

Reputation: 52837

Something like this:

validateProductsBeforeChanges(idProduct): Observable<Boolean>{
  return this._orderService.getAll()
  .pipe(
      map(orders => 
       orders.filter(x => x.products.find(y => y.code == idProduct))
             .map(filtered => filtered <= 0)
      )          
   );
}

Use like this: 

validateProductsBeforeChanges(id).subscribe(t=> {
     if (t) {
        ...
     }
     else {
       ...
     }
})

Upvotes: 1

Related Questions