CODEWITHSUNDEEP
reactjs
dagda1
dagda1

Reputation: 28890

setState called in render prop is causing a react warning

I have the following component that takes a render prop that it passes values to a child component. Here is a codesandbox that shows the problem. Press submit and look at the console.

Here is the component:

export const FormContainer = function FormContainer<V>({
  initialValues,
  validate,
  render,
  ...rest
}: FormContainerProps<V>) {
  const [hasValidationError, setHasValidationError] = useState(false);
  const dispatch = useDispatch();

  useEffect(() => {
    if (!hasValidationError) {
      return;
    }

    scrollToValidationError();

    () => setHasValidationError(false);
  }, [hasValidationError]);

  return (
    <>
      <Formik
      >
        {({
          isSubmitting,
          submitCount,
          isValid,
          errors,
          values,
        }: FormikProps<V>) => {
          const invalid = !isValid;
          const submitted = submitCount > 0;

          if (submitCount > 0 && invalid) {
            setHasValidationError(true);
          }

          return (
            <>
              <Form>
                  <div className={styles.form}>
                    {render({
                      values,
                      errors,
                      isSubmitting,
                      invalid,
                      submitCount,
                    })}
                  </div>
              </Form>
            </>
          );
        }}
      </Formik>
    </>
  );
};

If there is a validation error then setHasValidationError is called which causes this error from react

Warning: Cannot update a component (`FormContainer`) while rendering a different component (`Formik`). To locate the bad setState() call inside `Formik`, follow the stack trace as described in 
    in Formik (created by FormContainer)
    in FormContainer (created by Home)
    in Home (created by Context.Consumer)
    in Route (created by App)
    in Switch (created by App)
    in Router (created by App)
    in App

I'm not saying this warning is wrong. Calling setHasValidationError does not seem ideal here but the call to scrollToValidationError(); that will get called in the initial useEffect hook is async and it needs to go outside the render function.

What can I do?

Upvotes: 8

Views: 4545

Answers (2)

hackape
hackape

Reputation: 19987

I think Ali's answer using setTimeout is legit. I'd like to add that useEffect is IMO better solution. For it further prevent the unlikely but still possible error case when setHasValidationError is called after the component got unmounted.

(eslint naively complains useEffect is unsafe to use here but I checked with source code it's totally fine.)

// here I rename useEffect to mute eslint error
const nextTick = useEffect;

<Formik>
  {({
    isSubmitting,
    submitCount,
    isValid,
    errors,
    values
  }: FormikProps<V>) => {
    const invalid = !isValid;

    nextTick(() => {
      if (submitCount > 0 && invalid) {
        setHasValidationError(true);
      }
    }, [submitCount, invalid]);

    // ...
  }
</Formik>

Upvotes: 2

Ali Nasserzadeh
Ali Nasserzadeh

Reputation: 1449

In order to avoid this issue with Formik, you can wrap your state calls in setTimeouts, this should do the deal:

        setTimeout(() => setHasValidationError(true), 0);

This is also what Formik does in their official documentation. It's a problem they have had for a while, the trick is to make the state update run on the next cycle tick.

Also see: https://github.com/jaredpalmer/formik/issues/1218

Upvotes: 11

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