Variable of known type becomes “undefined” when passed from server side (.gs) to client-side(html) in Google Apps Script

Question

In google apps script, i've got an html file with an onsuccess callback function that calls a server side function, which grabs some data from the spreadsheet in question, then should return the data, stored in a variable, back to the html script function onsuccess.

i've already done this before successfully. this is why i am so perplexed at why, for some reason, the variable that i am returning from server side becomes 'undefined' once it is back to client side function.

i assumed it is some kind of Type Error, so i've played around with converting the variable (which is a very small array with three elements at most) and/or elements of the array to known types (string, int) and then pushing those into new variables and making a new array that contains the new known-type elements. also checked the original array elements using "typeof", and they are strings, as expected, so i became even more confused, because it doesn't seem like a TypeError.

html call-back function: (edited down to show essentials)

google.script.run.withSuccessHandler(

          function (flavors) 
           {            
            console.log(flavors);  // undefined
           }
        ).getBatchFlavs();

code.gs: (edited down to show essentials)

function getBatchFlavs() {

  var ss = SpreadsheetApp.getActive();
  var sheet = ss.getSheetByName("Flavoring");
  var data = sheet.getDataRange().getValues();
  var flavCell = sheet.getRange(1,3);

  data.forEach(function(row,i) {

    var rule = flavCell.getDataValidation();

      if (rule != null) 
        {
          var flavs = rule.getCriteriaValues(); 
          var flavors = flavs[0]; 

          Logger.log(flavors);  // shows exactly what i'm expecting
          Logger.log(typeof flavors);                 

          return flavors;  
        }
  })
}

console.log prints "undefined".

I included the part of the .gs code where i am getting the data for the variable i want to pass to client-side from a cell with datavalidation options which are strings. i thought perhaps this may be creating some weird variable type or something unknown, but as i said, i already checked the type with "typeof" and the items in the flavors array are indeed strings.

Answer 1

There are some restrictions in what can be passed. Please read this Parameters & Return Values

I did this example and this works:

function showmydialog() {
  var html='<html><head><script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script><link rel="stylesheet" href="//code.jquery.com/ui/1.12.1/themes/base/jquery-ui.css"><script src="https://code.jquery.com/ui/1.12.1/jquery-ui.js"></script></head><body>';
  html+='<div id="tst"></div>';
  html+='<script>$(function(){google.script.run.withSuccessHandler(function(vA){$("#tst").html(vA.join());}).getMyFlavors();});</script>';
  var ui=HtmlService.createHtmlOutput(html);
  SpreadsheetApp.getUi().showModelessDialog(ui, "Flavors");
}

function getMyFlavors() {
  var ss=SpreadsheetApp.getActive();
  var sh=ss.getSheetByName('Sheet2');
  var rg=sh.getRange('A1');//this has the data validation from the flavors named range
  var rule = rg.getDataValidation();
  if (rule != null) 
  {
    var flavs = rule.getCriteriaValues();      
    //return flavs[0].getValues();  
    return rule.getCriteriaValues()[0].getValues().map(function(r){return r[0];}); //This should flatten out the array.
  }
}

I created a named range called flavors.

This is what my spreadsheet looks like:

This is what my dialog looks like:

The data gets loaded onto the page via the dom ready function.

Answer 2

Issue:

There's no return value from the server side function getBatchFlavs() . The return flavors; only returns the value to anonymous callback function passed to the Array#forEach .

Solution:

return something from the function called from google.script.run - getBatchFlavs()

Snippet:

function getBatchFlavs() {//<================
  data.forEach(function(row, i) {//<==      |
    if (rule != null) {//            |      |
      var flavors = flavs[0];//      |      |
      Logger.log(flavors); //        |      |
      return flavors;//==============       |
    }//                                     |
  });//                                     |
  return flavors;//=========================
}

Variable of known type becomes “undefined” when passed from server side (.gs) to client-side(html) in Google Apps Script

Question

2 answers

solution1
0 2019-07-02 16:37:33

solution2
0 ACCPTED 2019-07-02 18:13:18

Issue:

Solution:

Snippet:

Variable of known type becomes “undefined” when passed from server side (.gs) to client-side(html) in Google Apps Script

Question

2 answers

solution1 0 2019-07-02 16:37:33

solution2 0 ACCPTED 2019-07-02 18:13:18

Issue:

Solution:

Snippet:

solution1
0 2019-07-02 16:37:33

solution2
0 ACCPTED 2019-07-02 18:13:18