Partial Relational Data Live Preview

body {
  padding: 4px;
  background: white;
}

setInitialRoutes(["/posts"]);

// visible-block-start
import React from "react";
import {
  useTable,
  // highlight-next-line
  useMany,
  HttpError,
} from "@refinedev/core";

// highlight-start
interface ICategory {
  id: number;
  title: string;
}
// highlight-end

interface IPost {
  id: number;
  title: string;
  content: string;
  status: "published" | "draft" | "rejected";
  createdAt: string;
  // highlight-start
  category: {
    id: number;
  };
  // highlight-end
}

const PostList: React.FC = () => {
  const { tableQuery } = useTable<IPost, HttpError>();
  const posts = tableQuery?.data?.data ?? [];

  // highlight-start
  // Fetches the category of each post. It uses the useMany hook to fetch the category data from the API.
  const { data: categoryData, isLoading: categoryIsLoading } = useMany<
    ICategory,
    HttpError
  >({
    resource: "categories",
    // Creates the array of ids. This will filter and fetch the category data for the relevant posts.
    ids: posts.map((item) => item?.category?.id),
    queryOptions: {
      // Set to true only if the posts array is not empty.
      enabled: !!posts.length,
    },
  });
  // highlight-end

  if (tableQuery?.isLoading) {
    return <div>Loading...</div>;
  }

  return (
    <div>
      <h1>Posts</h1>
      <table>
        <thead>
          <tr>
            <th>ID</th>
            <th>Title</th>
            <th>Status</th>
            <th>Created At</th>
            <th>Category</th>
          </tr>
        </thead>
        <tbody>
          {posts.map((post) => (
            <tr key={post.id}>
              <td>{post.id}</td>
              <td>{post.title}</td>
              <td>{post.status}</td>
              <td>{new Date(post.createdAt).toDateString()}</td>
              <td>
                {categoryIsLoading
                  ? "loading..."
                  : // Gets the title of the category from the categoryData object, which is the result of    the useMany hook.
                    categoryData?.data.find(
                      (item) => item.id === post.category.id,
                    )?.title || "-"}
              </td>
            </tr>
          ))}
        </tbody>
      </table>
    </div>
  );
};
// visible-block-end

setRefineProps({
  resources: [
    {
      name: "posts",
      list: PostList,
    },
  ],
});

render(
  <ReactRouter.BrowserRouter>
    <RefineHeadlessDemo>
      <ReactRouter.Routes>
        <ReactRouter.Route path="/posts" element={<PostList />} />
      </ReactRouter.Routes>
    </RefineHeadlessDemo>
  </ReactRouter.BrowserRouter>,
);