react admin console Error: Unknown dataProvider function: toJSON

Question

I'm facing an issue in react-admins ra-data-json-server.

import jsonServerProvider from 'ra-data-json-server';

const dataProvider = jsonServerProvider('https://jsonplaceholder.typicode.com');

export default function App() {
    return (
        <Admin dataProvider={dataProvider}>
            <Resource
                name="posts"
                list={ListGuesser}
                show={ShowGuesser}
                edit={EditGuesser}
            />
        </Admin>
    );
}

getting the console error:

Error: Unknown dataProvider function: toJSON
    at Proxy.eval (useDataProvider.ts:96:31)
    at JSON.stringify (<anonymous>)
    at Object.parseData (<anonymous>:8:116)
    at <anonymous>:10:2186
    at Array.reduce (<anonymous>)
    at <anonymous>:10:2114
    at i (<anonymous>:10:2706)
    at <anonymous>:10:2993
    at _ (<anonymous>:10:3119)
    at <anonymous>:10:3363

The application is running, the data that is fetched looks correct, but i can not get rid of the console error of the react_devtools_backend.

I created a minimal react-admin app using the jsonplaceholder api on stackblitz.io. Even there the console error is showing up every time.

Url to the minimal app where you can see the console error if you have react-dev-tools installed: https://react-ts-rj6rfi.stackblitz.io/#/posts

Used packages:

• react-admin: 4.5.2
• ra-data-json-server: 4.5.2
• react: 18.2.0
• react-dom: 18.2.0

Answer 1

If you're using the JSONPlaceholder API, why don't you use ra-data-json-server instead of ra-data-simple-rest ? The former is designed for that API language.

As for your error, the latest react-admin codebase doesn't have a single toSJON call. So the error must come from another package in your installation. And your error message doesn't help because the trace only shows <anonympus> ...