Cursor based pagination graphql

Question

I am retrieving data from graphql over a koa-server. For that, I wrote a function requestData(token, queryName, cursor) to call the graphql.

I would like to repeat the request until the cursor is null or undefined.

I always need to use the last cursor:

lastCursor = edges[edges.length - 1].cursor;

In the terminal I am getting following outputs:

null
eyJsYXN0X2lkIjo2MTQzNTk3ODcxMjc0LCJsYXN0X3ZhbHVlIjoiNjE0MzU5Nzg3MTI3NCJ9

I am getting this output even though I have more data. Can someone help me figure out what is wrong with my code?

server.js part

  router.post('/getAllProducts', bodyParser(), async (ctx, next) => {
    let data;
    let edges;
    let lastCursor = null;
    const { accessToken } = ctx.session;
    ctx.response.status = 200;

    requestData(accessToken, GET_ALL_PRODUCTS, lastCursor).then((res) => {
      data = res.data.data;
      edges = data.products.edges;
      lastCursor = edges[edges.length - 1].cursor;
      setTimeout(() => {
        requestData(accessToken, GET_ALL_PRODUCTS, lastCursor);
      }, 1000);
    });
  });

  function requestData(token, queryName, cursor) {
    const variables = { after: cursor };
    console.log(cursor);
    const res = axios({
      headers: {
        'X-Shopify-Access-Token': token,
      },
      method: 'post',
      data: {
        query: queryName,
        variables: variables,
      },
      url: url,
    });

    return res;
  }

Answer 1

It seems that you need to implement some recursion to your code - like this:

  router.post('/getAllProducts', bodyParser(), async (ctx, next) => {
    let allProducts;
    const { accessToken } = ctx.session;
    ctx.response.status = 200;

    function loadData(cursor) {
      requestData(accessToken, GET_ALL_PRODUCTS, cursor).then((res) => {
        const data = res.data.data;
        // process data here, eg: allProducts = [...allProducts, ...data];
        const edges = data.products.edges;
        const nextCursor = edges.length ? edges[edges.length - 1].cursor : null;
        if (nextCursor) {
          setTimeout(() => {
            loadData(nextCursor);
          }, 1000);
        } else {
          // now we have all data
          sendToClient(allProducts);
        }
      });
    }
    loadData(null);
  });

  function requestData(token, queryName, cursor) {
    const variables = { after: cursor };
    console.log(cursor);
    const res = axios({
      headers: {
        'X-Shopify-Access-Token': token,
      },
      method: 'post',
      data: {
        query: queryName,
        variables: variables,
      },
      url: url,
    });

    return res;
  }