CODEWITHSUNDEEP
reactjsreduxredux-saga
dsollen
dsollen

Reputation: 6459

Is it bad practice to do calculations and data tweaking in the saga in react?

I have a saga which runs once every 10 seconds on a POLL action to updated the current state on my GUI.

when a POLL happens I need to make a few calls to walk down the rest interface to get to find the components I care about. There will be a total of 1-5 components, for each of these I need to make a separate rest call for Foo and Bar elements of the components.

Then at some point I need to do some summations, combining the Foo and Bar data together to have the structure expected by my table for listing components, calculating some totals across all components in my dashboard etc. None of the work is cpu intensive, but it adds up to a decent bit of code since I have so many things that need tweaked.

Currently I'm doing all of this in the Saga, but I'm not sure if this is considered bad practice? I feel like reducers are the general 'go to' place for data tweaking, but it feels odd throwing an action with such a large payload, all the responses from every call in a saga, since much of the rest response is data I don't care about. I also like doing all the processing in the saga so I can decide at the end of everything rather to pass an error action to show an error to the user or pass a success action which clears any previous errors, some of the decision for rather I want to clear the action requires more processing of the data.

My only concern is that the generator is getting rather large, with lots of helper methods that feel a little out of place in a saga class to do the processing (their need to be moved to a utils class no matter what I think). The processing isn't too expensive and I am using generators so I don't think the processing will have a noticeable affect on saga's 'threading'. Still, If there is a recommended best practice I want to stick to that. Am I breaking from standard practices doing all of my tweaking of the data in my saga and sending to the reducer a per-formatted object for it to store into the state without any other processing?

Upvotes: 4

Views: 533

Answers (1)

markerikson
markerikson

Reputation: 67539

This is really a specific case of a common question that is addressed by the Redux FAQ on "where should my business logic live?". Quoting that answer:

Now, the problem is what to put in the action creator and what in the reducer, the choice between fat and thin action objects. If you put all the logic in the action creator, you end up with fat action objects that basically declare the updates to the state. Reducers become pure, dumb, add-this, remove that, update these functions. They will be easy to compose. But not much of your business logic will be there. If you put more logic in the reducer, you end up with nice, thin action objects, most of your data logic in one place, but your reducers are harder to compose since you might need info from other branches. You end up with large reducers or reducers that take additional arguments from higher up in the state.

There's nothing wrong with having logic on the "action creation" side (whether it be in components, thunks, sagas, or middleware) that does a lot of work to prepare and format data, and having the reducer simply store what was included in the action. On the flip side, having more logic on the reducer side can mean that time-travel debugging will re-run more of your actual code, giving you more chances to edit and retry behavior.

Overall, it sounds like what you're doing is perfectly reasonable.

Upvotes: 3

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