How to debug Google Apps Script (aka where does Logger.log log to?)

Question

In Google Sheets, you can add some scripting functionality. I\'m adding something for the onEdit event, but I can\'t tell if it\'s working. As far as I can tell

Answer 1

A little hacky, but I created an array called "console", and anytime I wanted to output to console I pushed to the array. Then whenever I wanted to see the actual output, I just returned console instead of whatever I was returning before.

    //return 'console' //uncomment to output console
    return "actual output";
}

Answer 2

just debug your spreadsheet code like this:

...
throw whatAmI;
...

shows like this:

Answer 3

Currently you are confined to the container bound nature of using scripts within docs. If you create a new script inside outside of docs then you will be able to export information to a google spreadsheet and use it like a logging tool.

For example in your first code block

function setCheckboxes() {

    // Add your spreadsheet data
    var errorSheet = SpreadsheetApp.openById('EnterSpreadSheetIDHere').getSheetByName('EnterSheetNameHere');
    var cell = errorSheet.getRange('A1').offset(errorSheet.getLastRow(),0);

    // existing code
    var checklist = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("checklist");
    var checklist_data_range = checklist.getDataRange();
    var checklist_num_rows = checklist_data_range.getNumRows();

    // existing logger
    Logger.log("checklist num rows: " + checklist_num_rows);

   //We can pass the information to the sheet using cell.setValue()
    cell.setValue(new Date() + "Checklist num rows: " + checklist_num_rows);

When I'm working with GAS I have two monitors ( you can use two windows ) set up with one containing the GAS environment and the other containing the SS so I can write information to and log.

Answer 4

The dev console will log errors thrown by the app script, so you can just throw an error to get it logged as a normal console.log. It will stop execution, but it might still be useful for step by step debugging.

throw Error('hello world!');

will show up in the console similarly to console.log('hello world')

Answer 5

UPDATE:

As written in this answer,

• Stackdriver Logging is the preferred method of logging now.

• Use console.log() to log to Stackdriver.

---

Logger.log will either send you an email (eventually) of errors that have happened in your scripts, or, if you are running things from the Script Editor, you can view the log from the last run function by going to View->Logs (still in script editor). Again, that will only show you anything that was logged from the last function you ran from inside Script Editor.

The script I was trying to get working had to do with spreadsheets - I made a spreadsheet todo-checklist type thing that sorted items by priorities and such.

The only triggers I installed for that script were the onOpen and onEdit triggers. Debugging the onEdit trigger was the hardest one to figure out, because I kept thinking that if I set a breakpoint in my onEdit function, opened the spreadsheet, edited a cell, that my breakpoint would be triggered. This is not the case.

To simulate having edited a cell, I did end up having to do something in the actual spreadsheet though. All I did was make sure the cell that I wanted it to treat as "edited" was selected, then in Script Editor, I would go to Run->onEdit. Then my breakpoint would be hit.

However, I did have to stop using the event argument that gets passed into the onEdit function - you can't simulate that by doing Run->onEdit. Any info I needed from the spreadsheet, like which cell was selected, etc, I had to figure out manually.

Anyways, long answer, but I figured it out eventually.

---

EDIT:

If you want to see the todo checklist I made, you can check it out here

(yes, I know anybody can edit it - that's the point of sharing it!)

I was hoping it'd let you see the script as well. Since you can't see it there, here it is:

function onOpen() {
  setCheckboxes();
};

function setCheckboxes() {
  var checklist = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("checklist");
  var checklist_data_range = checklist.getDataRange();
  var checklist_num_rows = checklist_data_range.getNumRows();
  Logger.log("checklist num rows: " + checklist_num_rows);

  var coredata = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("core_data");
  var coredata_data_range = coredata.getDataRange();

  for(var i = 0 ; i < checklist_num_rows-1; i++) {
    var split = checklist_data_range.getCell(i+2, 3).getValue().split(" || ");
    var item_id = split[split.length - 1];
    if(item_id != "") {
      item_id = parseInt(item_id);
      Logger.log("setting value at ("+(i+2)+",2) to " + coredata_data_range.getCell(item_id+1, 3).getValue());
      checklist_data_range.getCell(i+2,2).setValue(coredata_data_range.getCell(item_id+1, 3).getValue());
    }
  }
}

function onEdit() {
  Logger.log("TESTING TESTING ON EDIT");
  var active_sheet = SpreadsheetApp.getActiveSheet();
  if(active_sheet.getName() == "checklist") {
    var active_range = SpreadsheetApp.getActiveSheet().getActiveRange();
    Logger.log("active_range: " + active_range);
    Logger.log("active range col: " + active_range.getColumn() + "active range row: " + active_range.getRow());
    Logger.log("active_range.value: " + active_range.getCell(1, 1).getValue());
    Logger.log("active_range. colidx: " + active_range.getColumnIndex());
    if(active_range.getCell(1,1).getValue() == "?" || active_range.getCell(1,1).getValue() == "?") {
      Logger.log("made it!");
      var next_cell = active_sheet.getRange(active_range.getRow(), active_range.getColumn()+1, 1, 1).getCell(1,1);
      var val = next_cell.getValue();
      Logger.log("val: " + val);
      var splits = val.split(" || ");
      var item_id = splits[splits.length-1];
      Logger.log("item_id: " + item_id);

      var core_data = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("core_data");
      var sheet_data_range = core_data.getDataRange();
      var num_rows = sheet_data_range.getNumRows();
      var sheet_values = sheet_data_range.getValues();
      Logger.log("num_rows: " + num_rows);

      for(var i = 0; i < num_rows; i++) {
        Logger.log("sheet_values[" + (i) + "][" + (8) + "] = " + sheet_values[i][8]);
        if(sheet_values[i][8] == item_id) {
          Logger.log("found it! tyring to set it...");
          sheet_data_range.getCell(i+1, 2+1).setValue(active_range.getCell(1,1).getValue());
        }
      }

    }
  }

  setCheckboxes();
};

Answer 6

Just as a notice. I made a test function for my spreadsheet. I use the variable google throws in the onEdit(e) function (I called it e). Then I made a test function like this:

function test(){
var testRange = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(GetItemInfoSheetName).getRange(2,7)
var testObject = {
    range:testRange,
    value:"someValue"
}
onEdit(testObject)
SpreadsheetApp.getActiveSpreadsheet().getSheetByName(GetItemInfoSheetName).getRange(2,6).setValue(Logger.getLog())
}

Calling this test function makes all the code run as you had an event in the spreadsheet. I just put in the possision of the cell i edited whitch gave me an unexpected result, setting value as the value i put into the cell. OBS! for more variables googles gives to the function go here: https://developers.google.com/apps-script/guides/triggers/events#google_sheets_events