Dependent Data Validation in Google Apps Script - google-apps-script

Question

I need to add Data Validation to a range of cells based on the State chosen in the previous cell.
I've run this code which works ok for a limited amount of data but is not working on the actual spreadsheet.
function onEdit(e) { // Runs automatically when the user edits the sheet
var value = e.value; // Get the new value entered into the edited cell
var col = e.range.getColumn(); // Get the column number of the edited cell
var row = e.range.getRow(); // Get the row number of the edited cell
if (col == 6 && row >= 10 && row <= 854) { // Make sure that the edited cell is part of the table
var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName('Hoja 1');
var sheet2 = SpreadsheetApp.getActiveSpreadsheet().getSheetByName('Localidades'); // Get the sheet that has the table with the list of cities
var dropdownData = sheet2.getRange("A1:X594").getValues(); // Get the table with the list of cities.
var listOfCountries = dropdownData[0]; // The top row is the list of countries
var countryColumn = listOfCountries.indexOf(value); // Find the column in which the country name appears
if (countryColumn != -1) { // If the new country name is in the list
var cityList = [];
for (var dataRow = 1; dataRow < dropdownData.length; dataRow++) {
cityList.push(dropdownData[dataRow][countryColumn]);
}
var cityCell = sheet.getRange(row, col + 1);
cityCell
.clearDataValidations() // Remove any existing data validation in the target cell
.clearContent(); // Clear the cell
var rule = SpreadsheetApp.newDataValidation().requireValueInList(cityList, true).build();
cityCell.setDataValidation(rule);
}
}
}
I've debugged and it gets the CityList all right so don't know what's the problem really. Any help??

Answer 1

There is a limited amount of allowed dropdown options
Through testing you can easily verify that it is 500 options.
So, if you hardcode "A1:X594" you are above the limit.
However, for most of the provinces in your data the amount of options is less than 594 and your array contains many empty values.
You can remove all duplicates inlcuding emoty values by filtering, e.g.
cityList = cityList.filter(function (value, index, self) {
return self.indexOf(value) === index;
})
As for the provinces where you have many entries (e.g. Buenos Aires), maybe you can try to subdivide it into smaller regions so you have less than 500 dropdown options per dropdown?