Getting Error: Rendered Fewer Hooks Than Expected. When Using Usestate

I am using react-admin framework. I wrote my custom component that displays images in a materialUI GridList. I had to implement useState function to determine what elements to disp

Solution 1:

This article by Kent C Dodds might be related.

Can't be sure that this is your answer, without more details about how you are using the custom component outside - but looks like a violation of the following rules of hooks (quoted from the article)

you need to make sure that the hooks are always called the same number of times for a given component.

Paraphrasing the article, if you use a component as a function call, say something like this:

return arr.map(CustomComponent)

... since it's being called and not "rendered", the component's hooks are being interpreted in scope of the parent component - and it would it would translate to something like this...

constParentComponent() {
  return arr.map((item) => {
     // no. of hooks in ParentComponent depends on number of itemsconst [mouseOver, setMouseOver] = useState(false);
     .. rest of your component
   }
}   

...which violates the above rules of hooks mentioned.

Replacing that with this:

arr.map((item) =><CustomComponentitem={item}/>)

makes React interpret the hooks as part of the custom component scope, and it doesn't them throw this error.

Hope this helps!

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Update

Adding the update here for posterity

The component in question did indeed have a function call like below:

{ids.map(id => GridTile({ id, record: data[id], basePath, classes, rowClick, getTileProps, resource }))}

Switching to rendering it fixed the issue:

{ids.map(id =><GridTileid={id}record={data[id] } basePath={basePath}classes={classes}rowClick={rowClick}getTileProps={getTileProps}resource={resource} /> )}