Is there a way to prevent form state being reset after server 400 error on an Edit form in react-admin? - react-admin

Question

I have an Edit component that contains a TabbedForm that has been set to pessimistic mode. I am also using a custom data provider based on react-admin's simple rest provider.
<Edit
title="Edit entity"
mutationMode="pessimistic"
{...props}
>
<TabbedForm>
<FormTab label="Details">
<TextInput source="name" />
</FormTab>
</TabbedForm>
</Edit>
There is a validation rule in the API that ensures that another entity with the same name does not exist.
When this validation fails, the server returns a 400 error with a message. I've set this up to display this error in a toast and this is working fine.
The problem I am having is that the entire form state gets reset when there is a 400 error response, so all progress that the user has made on the form has been lost. For example, if the original value of the name field was "Entity A", and I change this to "Entity B" and submit the form, the API discovers that there is already an entity with that name, returns back the error and then resets the name field back to "Entity A". If there were other fields on this form, they are all reset back to the original state as well.
It appears that there is another HTTP request that is sent to the API to get the entity by ID again after the 400 response comes back (i.e. the getOne method on the data provider is being called again).
Is there a way to prevent the form state being reset after a 400 response from the server?
I'm thinking an alternative solution is to prevent 400 errors coming back at all by using client-side validation - perhaps by adding a custom validator that performs an API request to check if there's an entity with that name.

Answer 1

I figured out a way to prevent the form being refreshed after a failure on submit by overriding the onFailure behaviour.
const onFailure = (error: any) => {
notify(
typeof error === "string"
? error
: error.message || "ra.notification.http_error",
{ type: "warning" }
);
};
I have only emitted the logic to refresh() the page as described in the react-admin documentation.
Reference: https://marmelab.com/react-admin/CreateEdit.html#onfailure