How to computed properties

[matzeeable]

Hey !

React Query looks so promising. I just read the complete documentation and tried to cover all cases within your existing application with MobX.

I found one thing I could not find a solution: mobx.computed: https://mobx.js.org/computeds.html

How could this be covered by RQ?

[TkDodo]

select is probably the closest thing you are looking for: https://tkdodo.eu/blog/react-query-data-transformations#3-using-the-select-option

[matzeeable]

Thanks for your fast answer. As I can see from the documentation, the result is not memorized. Imagine, you have a complex and "long-running" compution, this is done for every component you are using the query, nor?

[TkDodo]

the result is memoized and structurally shared per observer, if you provide a stable function. If it has no dependencies, you can just extract it to a stable reference. If it has dependencies, useCallback.

if you need to store the result for multiple observers, you can combine it with something like reselect to memoize per input.

[matzeeable]

Awesome! Thanks!