Writing A Data Provider

dataProvider.getList('posts', {
    pagination: { page: 1, perPage: 5 },
    sort: { field: 'title', order: 'ASC' },
    filter: { author_id: 12 },
})
.then(response => console.log(response));
// {
//     data: [
//         { id: 126, title: "allo?", author_id: 12 },
//         { id: 127, title: "bien le bonjour", author_id: 12 },
//         { id: 124, title: "good day sunshine", author_id: 12 },
//         { id: 123, title: "hello, world", author_id: 12 },
//         { id: 125, title: "howdy partner", author_id: 12 },
//     ],
//     pageInfo: {
//         hasPreviousPage: false,    
//         hasNextPage: true,
//     }
// }

import { HttpError } from 'react-admin';

export default {
    getList: (resource, params) => {
        return new Promise((resolve, reject) => {
            myApiClient(url, { ...options, headers: requestHeaders })
                .then(response =>
                    response.text().then(text => ({
                        status: response.status,
                        statusText: response.statusText,
                        headers: response.headers,
                        body: text,
                    }))
                )
                .then(({ status, statusText, headers, body }) => {
                    let json;
                    try {
                        json = JSON.parse(body);
                    } catch (e) {
                        // not json, no big deal
                    }
                    if (status < 200 || status >= 300) {
                        return reject(
                            new HttpError(
                                (json && json.message) || statusText,
                                status,
                                json
                            )
                        );
                    }
                    return resolve({ status, headers, body, json });
                });
        });
    },
    // ...
};

import { fetchUtils } from 'react-admin';
import { stringify } from 'query-string';

const apiUrl = 'https://my.api.com/';
const httpClient = fetchUtils.fetchJson;

export default {
    getList: async (resource, params) => {
        const { page, perPage } = params.pagination;
        const { field, order } = params.sort;
        const query = {
            sort: JSON.stringify([field, order]),
            range: JSON.stringify([(page - 1) * perPage, page * perPage - 1]),
            filter: JSON.stringify(params.filter),
        };
        const url = `${apiUrl}/${resource}?${stringify(query)}`;
        const { json, headers } = await httpClient(url);
        return {
            data: json,
            total: parseInt(headers.get('content-range').split('/').pop(), 10),
        };
    },

    getOne: async (resource, params) => {
        const url = `${apiUrl}/${resource}/${params.id}`
        const { json } = await httpClient(url);
        return { data: json };
    },

    getMany: async (resource, params) => {
        const query = {
            filter: JSON.stringify({ ids: params.ids }),
        };
        const url = `${apiUrl}/${resource}?${stringify(query)}`;
        const { json } = await httpClient(url);
        return { data: json };
    },

    getManyReference: async (resource, params) => {
        const { page, perPage } = params.pagination;
        const { field, order } = params.sort;
        const query = {
            sort: JSON.stringify([field, order]),
            range: JSON.stringify([(page - 1) * perPage, page * perPage - 1]),
            filter: JSON.stringify({
                ...params.filter,
                [params.target]: params.id,
            }),
        };
        const url = `${apiUrl}/${resource}?${stringify(query)}`;
        const { json, headers } = await httpClient(url);
        return {
            data: json,
            total: parseInt(headers.get('content-range').split('/').pop(), 10),
        };
    },

    create: async (resource, params) => {
        const { json } = await httpClient(`${apiUrl}/${resource}`, {
            method: 'POST',
            body: JSON.stringify(params.data),
        })
        return { data: json };
    },

    update: async (resource, params) => {
        const url = `${apiUrl}/${resource}/${params.id}`;
        const { json } = await httpClient(url, {
            method: 'PUT',
            body: JSON.stringify(params.data),
        })
        return { data: json };
    },

    updateMany: async (resource, params) => {
        const query = {
            filter: JSON.stringify({ id: params.ids}),
        };
        const url = `${apiUrl}/${resource}?${stringify(query)}`;
        const { json } = await httpClient(url, {
            method: 'PUT',
            body: JSON.stringify(params.data),
        })
        return { data: json };
    },

    delete: async (resource, params) => {
        const url = `${apiUrl}/${resource}/${params.id}`;
        const { json } = await httpClient(url, {
            method: 'DELETE',
        });
        return { data: json };
    },

    deleteMany: async (resource, params) => {
        const query = {
            filter: JSON.stringify({ id: params.ids}),
        };
        const url = `${apiUrl}/${resource}?${stringify(query)}`;
        const { json } = await httpClient(url, {
            method: 'DELETE',
            body: JSON.stringify(params.data),
        });
        return { data: json };
    },
};

import { ApolloClient, InMemoryCache, gql } from "@apollo/client";
import { omit } from "lodash";

const apiUrl = 'https://my.api.com/v1/graphql';

const client = new ApolloClient({
  uri: apiUrl,
  headers: { "x-graphql-token": "YYY" },
  cache: new InMemoryCache(),
  defaultOptions: {
    watchQuery: {
      fetchPolicy: 'no-cache',
      errorPolicy: 'ignore',
    },
    query: {
      fetchPolicy: 'no-cache',
      errorPolicy: 'all',
    },
  }
});

const fields = {
  posts: "id title body author_id created_at",
  authors: "id name"
};

export const dataProvider = {
  getList: (resource, { sort, pagination, filter }) => {
    const { field, order } = sort;
    const { page, perPage } = pagination;
    return client
      .query({
        query: gql`
            query ($limit: Int, $offset: Int, $order_by: [${resource}_order_by!], $where: ${resource}_bool_exp) {
                ${resource}(limit: $limit, offset: $offset, order_by: $order_by, where: $where) {
                    ${fields[resource]}
                }
                ${resource}_aggregate(where: $where) {
                    aggregate {
                        count
                    }
                }
            }`,
        variables: {
          limit: perPage,
          offset: (page - 1) * perPage,
          order_by: { [field]: order.toLowerCase() },
          where: Object.keys(filter).reduce(
            (prev, key) => ({
              ...prev,
              [key]: { _eq: filter[key] },
            }),
            {}
          ),
        },
      })
      .then((result) => ({
        data: result.data[resource],
        total: result.data[`${resource}_aggregate`].aggregate.count,
      }));
  },
  getOne: (resource, params) => {
    return client
      .query({
        query: gql`
            query ($id: Int!) {
                ${resource}_by_pk(id: $id) {
                    ${fields[resource]}
                }
            }`,
        variables: {
          id: params.id,
        },
      })
      .then((result) => ({ data: result.data[`${resource}_by_pk`] }));
  },
  getMany: (resource, params) => {
    return client
      .query({
        query: gql`
            query ($where: ${resource}_bool_exp) {
                ${resource}(where: $where) {
                    ${fields[resource]}
                }
            }`,
        variables: {
          where: {
            id: { _in: params.ids },
          },
        },
      })
      .then((result) => ({ data: result.data[resource] }));
  },
  getManyReference: (
    resource,
    { target, id, sort, pagination, filter }
  ) => {
    const { field, order } = sort;
    const { page, perPage } = pagination;
    return client
      .query({
        query: gql`
            query ($limit: Int, $offset: Int, $order_by: [${resource}_order_by!], $where: ${resource}_bool_exp) {
                ${resource}(limit: $limit, offset: $offset, order_by: $order_by, where: $where) {
                    ${fields[resource]}
                }
                ${resource}_aggregate(where: $where) {
                    aggregate {
                        count
                    }
                }
            }`,
        variables: {
          limit: perPage,
          offset: (page - 1) * perPage,
          order_by: { [field]: order.toLowerCase() },
          where: Object.keys(filter).reduce(
            (prev, key) => ({
              ...prev,
              [key]: { _eq: filter[key] },
            }),
            { [target]: { _eq: id } }
          ),
        },
      })
      .then((result) => ({
        data: result.data[resource],
        total: result.data[`${resource}_aggregate`].aggregate.count,
      }));
  },
  create: (resource, params) => {
    return client
      .mutate({
        mutation: gql`
            mutation ($data: ${resource}_insert_input!) {
                insert_${resource}_one(object: $data) {
                    ${fields[resource]}
                }
            }`,
        variables: {
          data: omit(params.data, ['__typename']),
        },
      })
      .then((result) => ({
        data: result.data[`insert_${resource}_one`],
      }));
  },
  update: (resource, params) => {
    return client
      .mutate({
        mutation: gql`
            mutation ($id: Int!, $data: ${resource}_set_input!) {
                update_${resource}_by_pk(pk_columns: { id: $id }, _set: $data) {
                    ${fields[resource]}
                }
            }`,
        variables: {
          id: params.id,
          data: omit(params.data, ['__typename']),
        },
      })
      .then((result) => ({
        data: result.data[`update_${resource}_by_pk`],
      }));
  },
  updateMany: (resource, params) => {
    return client
      .mutate({
        mutation: gql`
            mutation ($where: ${resource}_bool_exp!, $data: ${resource}_set_input!) {
                update_${resource}(where: $where, _set: $data) {
                    affected_rows
                }
            }`,
        variables: {
          where: {
            id: { _in: params.ids },
          },
          data: omit(params.data, ['__typename']),
        },
      })
      .then((result) => ({
        data: params.ids,
      }));
  },
  delete: (resource, params) => {
    return client
      .mutate({
        mutation: gql`
            mutation ($id: Int!) {
                delete_${resource}_by_pk(id: $id) {
                    ${fields[resource]}
                }
            }`,
        variables: {
          id: params.id,
        },
      })
      .then((result) => ({
        data: result.data[`delete_${resource}_by_pk`],
      }));
  },
  deleteMany: (resource, params) => {
    return client
      .mutate({
        mutation: gql`
            mutation ($where: ${resource}_bool_exp!) {
                delete_${resource}(where: $where) {
                    affected_rows
                }
            }`,
        variables: {
          where: {
            id: { _in: params.ids },
          },
        },
      })
      .then((result) => ({
        data: params.ids,
      }));
  },
};