Google Apps Script for POSTING JSON data to a Google Sheet. via http://mashe.hawksey.info/2014/07/google-sheets-as-a-database-insert-with-apps-script-using-postget-methods-with-ajax-example/

Code.gs

// Create or open an existing Sheet and click Tools > Script editor and enter the code below
// 1. Enter sheet name where data is to be written below
var SHEET_NAME = "Sheet1";
// 2. Run > setup
// 3. Publish > Deploy as web app
//    - enter Project Version name and click 'Save New Version'
//    - set security level and enable service (most likely execute as 'me' and access 'anyone, even anonymously)
// 4. Copy the 'Current web app URL' and post this in your form/script action
// 5. Insert column names on your destination sheet matching the parameter names of the data you are passing in (exactly matching case)

var SCRIPT_PROP = PropertiesService.getScriptProperties(); // new property service

// If you don't want to expose either GET or POST methods you can comment out the appropriate function
function doGet(e){
  return handleResponse(e);
}

function doPost(e){
  return handleResponse(e);
}

function handleResponse(e) {
  // shortly after my original solution Google announced the LockService[1]
  // this prevents concurrent access overwritting data
  // [1] http://googleappsdeveloper.blogspot.co.uk/2011/10/concurrency-and-google-apps-script.html
  // we want a public lock, one that locks for all invocations
  var lock = LockService.getPublicLock();
  lock.waitLock(30000); // wait 30 seconds before conceding defeat.
  
  try {
    // next set where we write the data - you could write to multiple/alternate destinations
    var doc = SpreadsheetApp.openById(SCRIPT_PROP.getProperty("key"));
    var sheet = doc.getSheetByName(SHEET_NAME); 
    // we'll assume header is in row 1 but you can override with header_row in GET/POST data
    var headRow = e.parameter.header_row || 1;
    var headers = sheet.getRange(1, 1, 1, sheet.getLastColumn()).getValues()[0];
    var nextRow = sheet.getLastRow()+1; // get next row
    var row = [];
    // loop through the header columns
    for (i in headers) {
      if (headers[i] == "Timestamp"){ // special case if you include a 'Timestamp' column
        row.push(new Date());
      } else { // else use header name to get data
        row.push(e.parameter[headers[i]]);
      }
    }
    // more efficient to set values as [][] array than individually
    sheet.getRange(nextRow, 1, 1, row.length).setValues([row]);
    // return json success results
    return ContentService
          .createTextOutput(JSON.stringify({"result":"success", "row": nextRow}))
          .setMimeType(ContentService.MimeType.JSON);
  } catch(e) {
    // if error return this
    return ContentService
          .createTextOutput(JSON.stringify({"result":"error", "error": e}))
          .setMimeType(ContentService.MimeType.JSON);
  } finally { //release lock
    lock.releaseLock();
  }
}

function setup() {
  var doc = SpreadsheetApp.getActiveSpreadsheet();
  SCRIPT_PROP.setProperty("key", doc.getId());
}

Hi, I'm using the modified version of the above code.gs from here.
`// 2017 by Daniel Eichhorn, https://blog.squix.org
// Inspired by https://gist.github.com/bmcbride/7069aebd643944c9ee8b
// Create or open an existing Sheet and click Tools > Script editor and enter the code below
// 1. Enter sheet name where data is to be written below
var SHEET_NAME = "Sheet1";
// 2. Publish > Deploy as web app
// - enter Project Version name and click 'Save New Version'
// - set security level and enable service (most likely execute as 'me' and access 'anyone, even anonymously)
// 3. Copy the 'Current web app URL' and post this in your form/script action

var SCRIPT_PROP = PropertiesService.getScriptProperties(); // new property service

// If you don't want to expose either GET or POST methods you can comment out the appropriate function
function doGet(e){
return handleResponse(e);
}

function doPost(e){
return handleResponse(e);
}

function handleResponse(e) {
Logger.log("arrived in handleResponse");
if(typeof e !== 'undefined')
var jsonData = JSON.parse(e.postData.contents);

try {
// next set where we write the data - you could write to multiple/alternate destinations
var doc = SpreadsheetApp.openById(SCRIPT_PROP.getProperty("key"));
var sheet = doc.getSheetByName(SHEET_NAME);

var nextRow = sheet.getLastRow()+1; // get next row
var row = [];
var headerRow = [];

row.push(jsonData.rssi);
row.push(jsonData.seqno);
row.push(jsonData.data);
var humidityHex = jsonData.data.substring(0, 2);
row.push(parseInt(humidityHex, 16));
var tempHex = jsonData.data.substring(2, 4);
row.push(parseInt(tempHex, 16) - 100);
var latHex = jsonData.data.substring(4, 10);
var lonHex = jsonData.data.substring(10, 16);
var latEncoded = parseInt(latHex, 16);
var lonEncoded = parseInt(lonHex, 16);
row.push((latEncoded / 8388606) * 90);
row.push((lonEncoded / 8388606) * 180);

row.push(jsonData.freq);
row.push(jsonData.ack);
row.push(jsonData.fcnt);
row.push(jsonData.dr);
row.push(jsonData.bat);
row.push(jsonData.port);
row.push(jsonData.snr);
row.push(jsonData.EUI);
row.push(jsonData.cmd);
row.push(jsonData.ts);

// more efficient to set values as [][] array than individually
sheet.getRange(nextRow, 1, 1, row.length).setValues([row]);
// return json success results
return ContentService
      .createTextOutput(JSON.stringify({"result":"success", "row": nextRow}))
      .setMimeType(ContentService.MimeType.JSON);

} catch(e) {
// if error return this
return ContentService
.createTextOutput(JSON.stringify({"result":"error", "error": e}))
.setMimeType(ContentService.MimeType.JSON);
}
}`

I get "TypeError: Cannot read property "contents" from undefined. (line 25, file "Code")" when put the URL of the deployed web app. It suggests that the jsonData maybe empty.

Actually, I'm doing a LoRa communication project where I get the GPS data from the Loriot server and post to the Google sheet which is same as the link that I get the modified Code.gs from.

In my application log in the Loriot server shows:
Error POSTing message | "err":"POSTing message to "https://script.google.com/macros/s/AKfycbyUaIl4t8PZxoXswCW2kc0I-ZfUl5DVucsD0CwtW3Rn4YAP2qpo/exec\" failed with 302 status code","appid":3195667320,"url":"https://script.google.com/macros/s/AKfycbyUaIl4t8PZxoXswCW2kc0I-ZfUl5DVucsD0CwtW3Rn4YAP2qpo/exec","seqno":641,"deveui":"47A9B2690026003A","data":{"statusCode":302},"message":"POSTing message to "https://script.google.com/macros/s/AKfycbyUaIl4t8PZxoXswCW2kc0I-ZfUl5DVucsD0CwtW3Rn4YAP2qpo/exec\" failed with 302 status code","targetUrl":"https://script.google.com/macros/s/AKfycbyUaIl4t8PZxoXswCW2kc0I-ZfUl5DVucsD0CwtW3Rn4YAP2qpo/exec","statusCode":302,"reqBody":null,"errName":"Error","instance":"nwk-1"

I hope to get some comment from Sir, as I stuck for many months on the issue of failed with 302 status and TypeError: Cannot read property "contents" from undefined. (line 25, file "Code"). Thanks a lot