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4. Building a Booking System with Google Apps ( Code )

Note: This is the 4th of 3 previous posts about hacking Google Apps to attempt to create a usable Booking System.

First run this code from the Script Editor. It will make you a "Calendar Sheet" with X number of items as columns and Y dates as rows.

function create_a_blank_calendar_sheet(){
  // Run this from the Script Editor to create a Calendar Sheet.
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.insertSheet("Calendar"); //this'll fail if there is one already...
  var result = Browser.inputBox("How many x items", "e.g 10 or 25 etc", Browser.Buttons.OK_CANCEL );
  if (result == "cancel"){
    //Browser.msgBox("CANCEL: " + result)
     sheet.insertColumnsAfter(1 ,result);
     for(i = 2; i < result; i++){
       ss.setColumnWidth(i, 18);
     var days_result = Browser.inputBox("How many days", "e.g 365", Browser.Buttons.OK_CANCEL );
     // dates down the sides
     var n = 1;
     for(i = 2; i < days_result; i++){
        var now = new Date();
        now.setDate(now.getDate() + n);

        day = now.getDay();
       sheet.getRange(i,1).setValue(now); // You can format the column without times yourself :-)
       //colour the weekend's background
       if (day ==6 | day == 0){
        sheet.getRange(i, 1, 1, result).setBackground("#d6d6d6");
Now some code to add an "Administration" menu that people can use to click on a cell and book a "something or other".

function onOpen() {

  var ss = SpreadsheetApp.getActiveSpreadsheet();
  //var sheet = ss.getSheets()[0];
  //{name: "Create A Calendar Sheet", functionName: "create_a_blank_calendar_sheet"}, // This is just for setting up.
  var menuEntries = [
                    {name: "Book this perch...", functionName: "book_perch"}, ]
  ss.addMenu("Administration", menuEntries);        

This is a bit of code where you name your column names. You might want to do this by hand, with "Apples, Oranges, Pears, Kumquats" etc.

function setup_headers(){
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.getSheetByName("Calendar")    ;  //Yours might be something else
  /*setup column names. Probably wise to stick to single words? I'm using p17, p18 etc.

  var number_of_columns = 70
  for(i = 2; i < 
number_of_columns; i++){


Now these two functions do the work of creating an Event in an actual calendar and marking the spreadsheet to say it has been booked.

function add_to_calendar(perch, str_date){
    var user = Session.getUser();
    var email = user.getEmail();
    var cal = CalendarApp.getCalendarById('**************');
    Logger.log (cal.getName() );// Just check you got the right one
    date = new Date( str_date );
    //weirdo hack date help! help! All day events always end up a day behind?
    date.setDate(date.getDate() + 1);
    var event = cal.createAllDayEvent( email, date );
    Utilities.sleep(6000); // This is so that Google Calendar can "catch up". Seriously.
    var msg = "Perch " + perch + " booked on " + date + " for " + email + "." ; // So is this...
    Utilities.sleep(6000); //And this...
      event.addEmailReminder(60) ;
      event.addGuest( email ) ; // This adds it to their calendar as a request.

  return 0 // All is OK
function book_perch(){
    // This is called from the Menu
   var user = Session.getUser();
   var email = user.getEmail();
  var ss = SpreadsheetApp.getActiveSheet();
  // work out which cell is selected. Probably need to work out IF it a "live cell"
  // or if it is booked already, if it's one of their bookings.
  var cell = ss.getActiveCell();
  var cellname = cell.getA1Notation();                    
  var range = ss.getActiveRange();
  var row = range.getRow();                    
  var colindex = range.getColumnIndex();
  // get the header name, e.g "p34"                  
  var perch_name = ss.getSheetValues(1, colindex, 1, 1)
  // get the row date value                  
  var date = ss.getSheetValues(row, 1, 1, 1)
  var error = add_to_calendar(perch_name, date);  
  if (error == 1){
     Logging.log("Something went wrong");
      // Only fill in the cell if the Calendar hasn't failed.              
      cell.setValue(email) ;
      cell.setFontColor( "#ffffff" );
      cell.setBackground( "#990000" );

And there it is. It'd be true to say, there's more that it doesn't do than it does. For example, if I delete an item created in the calendar ( for real ) the spreadsheet doesn't automatically make the slot available again, but this is doable with a Triggered check on each item.

It's an encouraging start though. My only nagging doubts about how to deal best with the delay between creating an event and being able to then manipulate it, because the code continues executing but the documentation says it can be minutes before your event appears in the Calendar. At the moment I'm just lobbing in a few delays() ... but that's not right is it?


  1. Sir, I am trying to collect ideas to build a simple booking system for 3 courts in my city, a user can open the app choose which court and choose the sport he want to book for..i want to implement google products in it so i can make it simple :/ hope so, can you provide me with suggestion since your app is close to it.


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