impCentral API Example Code: Data Pagination

pagination.js

// CONSTANTS
// Replace the 'USERNAME' and 'PASSWORD' values with your own
// Replace the 'ACCESS_TOKEN' value with one retrieved using 'products.js' at
// https://gist.github.com/ElectricImpSampleCode/f0fb7f8bd04be009beeb5ee86dbd406a
const USERNAME = '...'
const PASSWORD = '...'
const ACCESS_TOKEN = '...'
const API_URL = 'api.electricimp.com'
const API_VER = '/v5/'

// GLOBALS
var https = require('https');
var deployments = [];
var next = null;

// FUNCTIONS
function setOptions(verb, path, token) {
  // Returns an HTTPS request options object primed for API usage
  return {
    hostname: API_URL,
    path: API_VER + path,
    method: verb,
    headers: {
      'Content-Type': 'application/vnd.api+json',
      'Authorization': 'Bearer ' + token
    }
  };
}

function showError(resp) {
  console.log(`STATUS: ${resp.statusCode}`);
  console.log(`HEADERS: ${JSON.stringify(resp.headers)}`);
}

function getDeplopyments() {
  // Any previous iteration of getDeployments() will have updated the variable 'next'
  // with the URL of the next page of data, so make use of it - or default to the 
  // first page if 'next' is null
  let options;

  if (next) {
    options = setOptions('GET', 'deployments' + '?' + next.link, ACCESS_TOKEN);
  } else {
    options = setOptions('GET', 'deployments', ACCESS_TOKEN);
  }

  let req = https.request(options, (resp) => {
    // Construct the returned response body
    let body = '';
    resp.setEncoding('utf8');
    resp.on('data', (chunk) => { body += chunk; });

    // Code that's called when the body is retrieved
    resp.on('end', () => {
      if (body.length > 0) {
        try {
          // Is the returned data valid JSON?
          const data = JSON.parse(body);

          if (resp.statusCode === 200) {
            // 'data' is an array of deployment objects
            for (let item of data.data) {
              let dep = {};
              dep.id = item.id;
              dep.sha = item.attributes.sha;
              dep.deviceCode = item.attributes.device_code;
              dep.agentCode = item.attributes.agent_code;
              dep.deployed = item.created_at;
              
              // Add the deployment to the 'deployments' array
              deployments.push(dep);
           }

           // Check for paginated data
           if ('links' in data) {
             if ('next' in data.links) {
               // Split the link URL at the ?
               let narray = data.links.next.split('?');
                
               // If we have no 'next' 
               if (next === null) {
                 next = {};
                 next.count = 0;
               }
                
               // Update the next link and count of pages
               next.link = narray[1];
               next.count += 1;
               console.log(`Getting page ${next.count + 1} of deployments`);
                
               // Call the function again to get the next page
               getDeplopyments();
             } else {
               // We've received all the pages - report the fact
               next = null;
               console.log(`${deployments.length} deployments have been made to this account's Products`);
             }
           }
         } else {
           // API Error
           console.log('API ERROR: ' + data.code + ' (' + data.message + ')');
         }
      } catch (err) {
          // JSON error
          console.error(err.message);
        }
      } else {
        // HTTP Error
        showError(resp);
      }
    });
  });

  // Error callback
  req.on('error', (err) => { console.error(`REQUEST ERROR: ${err.message}`); });

  // Send the request
  req.end();
}

// RUNTIME
getDeplopyments();