Why another state management framework for Angular?
I didn’t set out to make my own state management system just for fun. I actually spent a lot of time trying to avoid creating my own. I created a library called ngrx-actions wraps NgRX to try to solve some of my pain points but in the end this just felt like a hack and I was always going to be making decisions on this new library based on the architecture of NgRX. In the end, I created a new state management system called NGXS which took many of the concepts of Redux but reimagined them for Angular.
So what were the gaps that I found and wanted to approach differently with this library?
Redux was designed for React
Redux was built for React. All the concepts around it, such as pure function reducers, are centered around the ergonomics of how React works, preferring functions over classes, etc. Since it was designed for React, it lacked the necessary plumbing to make it work well with Angular, thus NgRX was born. To me, NgRX still feels like a port of Redux rather than re-imagining of how the principles of CQRS would look like in the Angular world.
Its more Angular-like code style
Angular uses classes and decorators extensively. If we were not implementing a Redux pattern in our code base it is very unlikely we would actually have a pure function with a switch statement at all. I wanted to take the Angular code style to state management by using classes to describe state containers and decorators to describe actions to take on the state.
Angular is completely built around dependency injection. We use it EVERYWHERE! It gives us so many useful tools for development, but with pure functions we can’t access these functions. In React land, we don’t have DI so if we need to access a service like layer in our reducer we simply use the out-of-the-box service locator pattern and just import and use it. With Angular we want to use our DI and we can’t with Redux patterns.
In a typical NgRX setup we have: Actions, Effects, Reducers, Selects. That’s four files for what could easily be contained in one file. But wait, what about separation of concerns? Doesn’t this help us achieve that? Maybe, but all these items are dealing with the same state container, whether that is mutating the state or reaching out to a service and mutating the state from that service. NGXS does its best to reduce all this by creating simple state containers and actions associated to those.
Effects can be painful
NgRX Effects are a awesome approach to observable event streams but they can be painful to construct, read, maintain and teach to other devs. It feels like we need to be an RxJS expert to write them effectively and its really easy to cause unwanted side effects.
Listening to Dispatched Actions
It’s extremely common for us to dispatch a action that will reach out to a service and save something and then, after that happens, we need to show something in our component related to the result of that. There is not an easy way to know when that action chain has been completed, often times we end up creating pseudo models in our state and listening for those in our view. To be honest, that feels like something that shouldn’t even be in the state to begin with. It’d be nice to have an easy way to just listen to when something we dispatch is completed, and subscribe to dispatches with NGXS.
Observables are great but they aren’t a silver bullet. Sometimes we just want to deal with promises. NGXS allows us to use either.
Check it out!
If you too have these same frustrations, I encourage you to checkout NGXS. Its my solution to these frustrations and while its not perfect, nothing rarely is.