How to handle errors inside reducers?

Question

I've my loggerService and I need to catch all errors in reducer and send it via my service to the server.

How can I do it? I know that reducer should be a pure function, but still any ideas?

I need to add in reduser try catch

    case actions.GAMES_LOADED{
       ......
       try{}
       catch(err){
       this.loggerService.error(err);
    }
}

Or maybe throw something in reducer and catch it in some place...

Thanks a lot

Answer 1

Short answer: You don't.

Why? - The reducer is only responsible for updating the store, it should not perform any business-logic or validate data - any data that reaches the store should be already valid and just be stored/updated/removed from the store.

Possible solution: You should do these kind of operations either in an effect or in some service that is responsible for fetching/creating the data.

Answer 2

If you add to your application state a "loadingMessage" item, you can set that state in this reducer to empty or a message. This can then be read by a component using a store selector and if not empty, logged or a dialog produced or whatever you wish to do with this state.

Answer 3

I don't agree that reducer is only responsible for updating the store. It is rather responsible for updating application state..store as well as UI state. So in this case there is a valid responsibility for the reducer to update error state in the application. Upon redirection from effect on error by some error action reducer can update error state. However in that case same reducer should wipe out error state upon receiving any success action. But I am not suggesting that this is best practice.