Google App Script for Google Form: get displayName from Google+ ID

Google+ DB.js

/**
 * Set a trigger:
 *   onFormSubmit -> getDisplayName
 *
 * Form: Google+ ID (must be the first column in the form)
 *       or you need to change `id = e.values[1];` line
 *       in getDisplayName function to the correct column number
 *
 * Author: Balazs Nadasdi
 *         <[email protected]>
 *         https://plus.google.com/u/0/104695723888883478740/about
 */

var API_KEY = "API_KEY";
var API_PRE = "https://www.googleapis.com/plus/v1/";

// API Tools
function generateAPIUrl(path, parameters) {
  if (typeof path == "undefined") { return false; }
  if (typeof path != "object" || !(path instanceof Array)) { path = [ path ]; }
  if (typeof parameters == "undefined") { parameters = {}; }
  
  parameters.key = API_KEY;
  
  var query,
      parameters_array = [];

  for(var key in parameters) {
    parameters_array.push("" + key + "=" + parameters[key]);
  }
  
  query = API_PRE + path.join("/") + "?" + parameters_array.join("&");
  
  return query;
}

// Spreadsheet Tools
function getColIndexByName(colName) {
  var sheet = SpreadsheetApp.getActiveSheet();
  var numColumns = sheet.getLastColumn();
  var row = sheet.getRange(1, 1, 1, numColumns).getValues();
  for (i in row[0]) {
    var name = row[0][i];
    if (name == colName) {
      return parseInt(i) + 1;
    }
  }
  return -1;
}

// Event Handlers
function getDisplayName(e) {
  var id, response, user, sheet, lastRow;
  
  id = e.values[1];
  try {
    response = UrlFetchApp.fetch(
      generateAPIUrl(
        [ "people", id ],
        { "fields": "displayName" }
      )
    );
    user = JSON.parse(response.getContentText());
  } catch(err) {
    return false;
  }
  
  if (!user.hasOwnProperty('displayName')) {
    return false;
  }

  sheet = SpreadsheetApp.getActiveSheet();
  lastRow = sheet.getLastRow();
  return sheet.getRange(lastRow, getColIndexByName("DisplayName")).setValue(user.displayName);
}