In Google Sheets set dynamic dropdown with Apps Script - google-apps-script

Question

I'm trying to set a dynamic dropdown in Google Sheet using Apps Script. I managed to get most parts working except setting the data validation in the cells necessary:
function sheetByName(ssId, sheetName) {
var ss = SpreadsheetApp.openById(ssId);
var sheet = ss.getSheetByName(sheetName);
return sheet;
};
function columnByName(sheet, columnName) {
var data = sheet.getDataRange().getValues();
var column = data[0].indexOf(columnName);
return column;
};
function columnValues(sheet, index) {
var data = sheet.getDataRange().getValues();
var values = [];
for(n=1; n<data.length; ++n) {
values.push(data[n][index]);
}
return values;
}
function columnSetDataValidation(sheet, index, options) {
var data = sheet.getDataRange().getValues();
var rule = SpreadsheetApp.newDataValidation()
.requireValueInList(options)
.setAllowInvalid(true)
.build();
for(n=1; n<data.length; ++n) {
var cell = data[n][index];
};
};
function dropDownBedrijven() {
var sheetCollegas = sheetByName("<<ID HERE>>", "Collegas");
var sheetBedrijven = sheetByName("<<ID HERE>>", "Bedrijven");
var getColumnIndexInBedijven = columnByName(sheetBedrijven, "Bedrijf");
var getColumnIndexInCollegas = columnByName(sheetCollegas, "Bedrijf");
var bedrijven = columnValues(sheetBedrijven, getColumnIndexInBedijven).filter(item => item);
columnSetDataValidation(sheetCollegas, getColumnIndexInCollegas, bedrijven);
};
I can't manage to get the function columnSetDataValidation to set data validation in the required cells.
Do you have any idea how to go about it?

Answer 1

You need to use range.setDataValidation(rule) with a range.
In your function columnSetDataValidation you are correctly building the rule, but are failing to assign the rule to a range. You are looping over the values of the range and then changing the value of var cell until the loop ends. Nowhere did you call range.setDataValidation(rule).
Try the following solution:
function columnSetDataValidation(sheet, index, options) {
var range = sheet.getDataRange();
var rule = SpreadsheetApp.newDataValidation()
.requireValueInList(options)
.setAllowInvalid(true)
.build();
for(n = 1; n < range.getLastRow(); ++n) {
var cell = range.getCell(n,index);
cell.setDataValidation(rule);
};
};
References:
Range.getCell(row, column)
Range.setDataValidation(rule)

Answer 2

Try this:
function columnSetDataValidation() {
const ss=SpreadsheetApp.getActive();
const sheet=ss.getSheetByName('Sheet1');
const range = sheet.getRange(2,4,sheet.getLastRow()-1);//putting validation in column 4
const options=[1,2,3,4,5];
const rule = SpreadsheetApp.newDataValidation()
.requireValueInList(options)
.setAllowInvalid(true)
.build();
range.setDataValidation(rule);
}