I am creating a MERN app that adds meta tags to React pages without SSR. So, I need to read the query inside the main file of the server and pass the appropriate metadata content to each page. I am using this in the server.js file:

const indexPath  = path.resolve(__dirname, 'build', 'index.html');

// static resources should just be served as they are
app.use(express.static(
    path.resolve(__dirname, 'build'),
    { maxAge: '30d' },
));
// here we serve the index.html page
app.get('/*', (req, res, next) => {
    fs.readFile(indexPath, 'utf8', (err, htmlData) => {
        if (err) {
            console.error('Error during file reading', err);
            return res.status(404).end()
        }
        // get post info
        const postId = req.query.id;
        const post = getPostById(postId);
        if(!post) return res.status(404).send("Post not found");

        // inject meta tags
        htmlData = htmlData.replace(
            "<title>React App</title>",
            `<title>${post.title}</title>`
        )
        .replace('__META_OG_TITLE__', post.title)
        .replace('__META_OG_DESCRIPTION__', post.description)
        .replace('__META_DESCRIPTION__', post.description)
        .replace('__META_OG_IMAGE__', post.thumbnail)
        return res.send(htmlData);
    });
});

Here the getPostById is statically defined in a file. But I want to fetch it from my db. My file structure is:

server.js
controllers

 - posts.js
routes
 - posts.js

I've separated the logic from route. So my routes/posts.js file looks like:

import { getPost, createPost } from '../controllers/posts.js';


const router = express.Router();

router.get('/', getPost);
router.post('/', createPost);


export default router;

So, in order to dynamically pass the meta content, I need to read the API endpoint for each request and pass the appropriate data. For this, I need to call the endpoints directly inside my node project. How to do that?

I'd appreciate any help. Thank you.