Passing context as second argument to onReceive callback

[matigda]

Hi there!
First of all I want to say that this is awesome tool! I'm working with it for a few months now and it really helped me solve some issues.

There is one design thing though that I don't really understand and it's making my life harder.

I have service that looks like that:

itemsService: (context: CheckoutContextSchema<ShippingMethodsType>, event: CheckoutEventSchema) => (cb: (event: object) => void, onReceive: any) => {
           onReceive(async (event: CheckoutEventSchema) => {

               if (event.type === EventId.ADD_PRODUCT_ON_BACKEND) {
                   let cartId: string;
                   if (!context.cartId) {
                       cartId = await createCart();
                       cb({type: EventId.ASSIGN_CART_ID, payload: {cartId}})
                   } else {
                       cartId = context.cartId
                   }

                   await addProductToCart(event.payload.product, event.payload.quantity, cartId);
                   cb({type: EventId.PRODUCT_ADDED});
               }
           })
       },

The issue here is that context is being used in a closure, so it never changes. So even though this line cb({type: EventId.ASSIGN_CART_ID, payload: {cartId}}) sets the cart id in context, this condition: if (!context.cartId) { always returns true. Can you tell me why context is not passed to onReceive function?

[davidkpiano]

The issue here is that context is being used in a closure, so it never changes.

Yes, that's the point. When you create the invoked callback (with the context at the time of its creation), the only way you can communicate between the parent/child is with events.

So, in order for this actor to receive some updated data, it needs to receive that data in an event (via onReceive).