Remove support for warnWhenUnsavedChange when react-router doesn't allow it

[fzaninotto]

Problem

React-router 6.4.0 removed support for navigator.block, which is necessary for the warnWhenUnsavedChanges feature (see remix-run/react-router#9262).

This breaks existing applications using react-router >= 6.4 and a custom router.

Solution

The warnWithUnsavedChanges feature fails silently when using with react-router >= 6.4

Closes #8163

[crates]

Is it possible to preempt the user's own onSubmit method (or alternatively, fired subsequent to the user's one) with one created by React Admin, so that when the warning prop is in use, it's that interstitial method that triggers first, thereby calling the warning up instead of submitting the form? That would not require any use of navigator.block, but would result in a similar outcome.

[fzaninotto]

@crates I'm not sure I understand. Are you suggesting that warnWhenUnsavedChange auto-submits the form when the user leaves the page without submitting? That would be very unexpected for most users.

[crates]

No, you are totally right. That suggestion made no sense.

How about a custom router component provided by React Admin? Something like what they are discussing on this thread?

https://stackoverflow.com/questions/69953377/react-router-v6-how-to-use-navigate-redirection-in-axios-interceptor

[TrejGun]

that actually still works with
remix-run/react-router#8139 (comment)

and custom history

import { FC } from "react";
import { unstable_HistoryRouter as HistoryRouter } from "react-router-dom";
import { history } from "history";


const App: FC = () => {
  return (
    <HistoryRouter history={history}>
      <YOUR CODE HERE>
    </HistoryRouter>
  );
};

export default App;

[crates]

@TrejGun - Agreed; that's what we're using on our project also, with React Router 6.4

[fzaninotto]

How about a custom router component provided by React Admin? Something like what they are discussing on this thread?

https://stackoverflow.com/questions/69953377/react-router-v6-how-to-use-navigate-redirection-in-axios-interceptor

@crates reimplementing a custom router is outside of the scope of react-admin. We have enough work without it ;)

that actually still works with
remix-run/react-router#8139 (comment)

and custom history

@TrejGun You're right, that's why the PR description says

This breaks existing applications using react-router >= 6.4 and a custom router.

So we have to prevent the app from breaking in that case, and that's why this PR is necessary.