Bdtjtk

I'm having issues trying to work with api "pagination", I need to merge multiple objects into one. However, I can't seem to figure out how to do this with promises and I'm not sure how to work with async/await to get the best results.

I have a class called selly, which works with the Selly API.

getAllProducts(page = 1) {

    return this.makeRequest('products', { page: page });

}

makeRequest(endpoint, params = {}) {

    return axios

        .get(`https://selly.gg/api/v2/${endpoint}`, {

            headers: {

                Authorization: `Basic ${this.genApiToken(this.apiKey, this.apiEmail)}`,

                'User-Agent': `username - localhost`,

            },

            params: params,

        })

        .catch((err) => {

            console.log(err);

        });

}

Which worked great, until I realized I need to fetch multiple pages and combine all of the results into a single object. Here's my attempt:

app.get('/api/products', (req, res) => {

    res.setHeader('Content-Type', 'application/json');

    selly.getAllProducts().then((request) => {

        const pages = request.headers['x-total-pages'];

        let products = request.data;

        if (pages > 1) {

            let i = 2;

            while (pages >= i) {

                selly.getAllProducts(i).then((nextPageRequest) => {

                    nextPageRequest.data.forEach((item) => {

                        products.push(item);

                    });

                });

                i++;

            }

        }

        res.send(JSON.stringify(products));

    });

});

I can't seem to push nextPageRequest to products object. Obviously because res.send runs before the promise selly.getAllProducts(i) is finished.

I understand that the best optimization for this is using async and await, however I just can't get the basic concept of it, or well, at-least how would I refactor my code into using async and await.

How can I get this working?

You can make the whole app.get handler async, then await the inital request to figure out how many pages there are, then use a for loop and await additional calls of selly.getAllProducts, pushing the result to the products array. Make sure to try/catch so you can handle errors:

app.get('/api/products', async (req, res) => {

  res.setHeader('Content-Type', 'application/json');

  try {

    const request = await selly.getAllProducts();

    const pages = request.headers['x-total-pages'];

    const products = request.data;

    for (let i = 2; i <= pages; i++) {

      const { data } = await selly.getAllProducts(i);

      products.push(...data);

    }

    res.send(JSON.stringify(products));

  } catch(e) {

    // handle errors

  }

});