Lucas' Refuge

What to put on the Redux state

May 20, 2020 - 3 min read


Following up the react/redux community these past years, I've seen many inquiring whether redux, or any equivalent state management solution, was even needed for achieving X or Z in a SPA. Alternatives such as using the context API, as a simpler redux clone, or even ignoring it altogether and going for component state were also common place.

Being not one to favour dichotomies, I won't try to convince you that redux is the way to go, given I myself had repented over using redux for some use cases. In hindsight one of those bad decisions involved adopting redux form for handling form state. If you asked me, a couple years ago, had you any need to have form data in redux specifically? I certainly couldn't raise one valid point for that. Of course redux form API was nice and facilitated form handling, but it also created its own share of problems.

Unfortunately react final form, formik and others weren't available at the time. So redux form just seemed right. That said I've had my own share of issues, especially when dealing with big forms. More specifically it dispatches a redux action per field registration, during initial render, which made forms with many fields feel sluggish. Still an issue present on it, which libraries relying on component state such as react final form and formik don't have. In fact even redux form's creator recommends the use of react final form nowadays, if you have no need to have form data in redux. It's worth mentioning that both were created by the same person.

With that I intend to exemplify that being adamant about a technical or methodological choice might cause you trouble anyway. Oh, I won't have such problems because I opted on using the context API instead of redux, you might say. But relying on the context API has its drawbacks. Most noticeably the fact that any change on the value of a given context provider will trigger a re-render of its underlying component tree, even if it changes something that your component isn't even using. Of course you can have your React.memo, PureComponent or shouldComponentUpdate life-cycle method in place, but that wouldn't be an issue with react redux. On react redux, assuming default behaviour, a re-render will only happen when the shallow comparison of the returned object's fields of the mapStateToProps is true or when the strict equality of the returned value of the useSelector hook is true. So as you see redux is better optimized when it comes to avoiding re-renders, which is paramount when you are connecting components at many levels of the component tree, as you should.

For those reasons, I'd recommend the following:

  • Use redux for interactions with the backend, which are tied to pages, not shareable components. Most GETs, PUTs, PATCHes and DELETEs should apply.
  • Use the context API for global level configuration, such as styles, internationalization, authentication info, user preferences and what not.
  • Use the component state for the kind of components that are shared across distinct pages (e.g. form handling, dialogs), even when those require backend interactions (e.g. autocomplete selects). Usually if you can't justify why you need redux, that's what you need.

What's your take on it? Do you agree? Do you have your own set of guidelines? Please follow up on the comments below.

Written by Lucas Lira Gomes who is fond of doing things that last and all that jazz. You should follow him on Twitter, GitHub, and LinkedIn.

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