Typescript complaining existing object doesn't exist

Question

From CartComponent I am calling the removeItem() function in CartService.

CartComponent#removeItem():

public removeItem(itemId:string) {
    this.cartService.removeItem(itemId).subscribe(cart => {
      console.log('CartComponent#removeItem', )
      this.cartItems = cart.cartItem;
    });
  }

Typescript is giving the following error for cart.cartItem:

[ts] Property 'cartItem' does not exist on type 'void'.
any

I have done precisely this in another application and it works just fine.

CartService#removeItem()

public removeItem(itemId:string) {
   console.log('CartService#removeItem', itemId)
   return this.httpClient.delete<Cart>(`${this.cartItemUrl}${itemId}`)
   .pipe(
     tap(cart => console.log('cart@removeItem', cart)),
     // map(cart => this.cart = cart, this.setItemCount()),
     map(cart => {
       this.cart = cart;
       this.setItemCount();
     }),
     catchError(this.handleError.bind(this))
   )
 }

user184994 · Accepted Answer · 2018-08-12 14:25:34Z

2

The map function is used to transform the emitted value of the Observable. Whatever is returned from map will be the emitted value.

If your case, nothing is returned from your map function, so the subscribe in CartComponent has no way of accessing the value.

answered Aug 12, 2018 at 14:25

user184994

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3 Comments

koque Over a year ago

I do have a return statement in CartService#removeItem and this worked in other codes.

user184994 Over a year ago

No, you need another one inside the map function, underneath this.setItemCount() you probably want return this.cart as well. If map doesn't return anything your observable will emit undefined

dAxx_ Over a year ago

just a side note, use map when you are trying to map the response, in example, transform it to something else. what you did inside the map has nothing to do with the response transformation, hence, do it inside the tap. so the response won't change, but you may want to do other stuff related to the response inside the service itself (like your console.log)

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