import express from "express";
import { expressDataProvider } from "ra-data-server";

const handlers = {
    getList: ...,
    ...
};

const dataProviderMiddleware = expressDataProvider(handlers);

const app = express();
app.use(express.json());
app.use("/admin", dataProviderMiddleware);
app.listen("3000");

// in src/App.js
import * as React from "react";
import { Admin, Resource } from "react-admin";
import { serverSideDataProvider } from "ra-data-server";

import { PostList } from "./posts";

const App = () => (
    <Admin dataProvider={serverSideDataProvider("http://localhost:3000/admin")}>
        <Resource name="posts" list={PostList} />
    </Admin>
);

export default App;

{
    body: // json containing the traditional result of a dataProvider if all is good, an error object otherwise
    status: // the status code 200 if all is good
}

 const dataProvider = {
    async getList(
        resource,
        {
            pagination: { page, perPage },
            sort: { field, order },
            filter,
        }
    ) {
        // handle the logic to get the list for the resource using the params

        return {
            status: 200,
            body: {
                data: [/* The returned records */],
                total: // the total number of record matching the given filter,
                validUntil: // optional validity date
            },
        };
    }
    async getOne(
        resource,
        { id }
    ) {
        // handle the logic to get the record
        return {
            status: 200,
            body: {
                data: // the fetched record,
                validUntil: // optional validity date
            },
        };
    }
    async getMany(
        resource,
        { ids }
    ) {
        // handle the logic to get the records
        return {
            status: 200,
            body: {
                data: [/* the fetched record */],
                validUntil: // optional validity date
            },
        };
    }
    async getManyReference(
        resource,
        {
            target,
            id,
            pagination: { page, perPage },
            sort: { field, order },
            filter
        }
    ) {
        // handle the logic to get the records
        return {
            status: 200,
            body: {
                data: [/* the returned records */],
                total: // the total number of record matching the given filter,
                validUntil: // optional validity date
            },
        };
    }
    async update(
        resource,
        { id, data, previousData }
    ) {
        // handle the update logic
        return {
            status: 200,
            body: {
                data: /* the updated record */,
                validUntil: // optional validity date
            },
        };
    }
    async updateMany(
        resource,
        { ids, data }
    ) {
        // handle the updateMany logic
        return {
            status: 200,
            body: {
                data: [/* the updated records ids */],
                validUntil: // optional validity date
            },
        };
    }
    async create(
        resource,
        { data }
    ) {
        // handle the create logic
        return {
            status: 200,
            body: {
                data: /* the created record */,
                validUntil: // optional validity date
            },
        };
    }
    async delete(
        resource,
        { id, previousData }
    ) {
        // handle the delete logic
        return {
            status: 200,
            body: {
                data: /* the deleted record */,
            },
        };
    }
    async deleteMany(
        resource,
        { ids }
    ) {
        // handle the deleteMany logic
        return {
            status: 200,
            body: {
                ids: /* the ids of the deleted record */,
            },
        };
    }
};