Adding Asynchronous Events to Contexts

Adding Action Cable back

Now we can add the Action Cable subscription back to the system. There are two problems to solve, one of which is kind of logistical and the other of which is more philosophical.

The logistical problem is that if you look at what data our subscription used in the past version and look at what data is now in our VenueContext, we have a problem. The subscription uses the concert_id, which is data in the state.

However, it will also use the dispatch function because the subscription receives data about what tickets have been held from the Action Cable channel and uses dispatch to update global state based on that data. We use that data to redraw the screen, which means the subscription needs to know how to update the context state, which means the subscription needs to know the dispatch function and the reducer.

Creating a new context

There are a few different ways of managing this problem. The one I’ve chosen is to create a new context: