App script not depending on column position - google-apps-script

Question

I want to be able to insert columns in my data or rearrange column positions without affecting the appscript functions.
Instead of referring to column positions by number, I thought of referring to them by header values (I will not change the names).
I made a small function which will make it easy for writing the code.
The output of the function will be stored in the sheet and then I will copy paste it to my app script function.
Is my approach all right or is there a better way to do it?
function get_headers(){
var ss=SpreadsheetApp.getActiveSpreadsheet();
var sheets=ss.getSheets();
var fin=[];
var tsheet=ss.getSheetByName("Product");
var shtname=tsheet.getName();
var [hd_Product, ...data_Product] = tsheet.getDataRange().getDisplayValues();
for (j=0;j<hd_Product.length;j++) { fin.push("const "+shtname+"_"+hd_Product[j]+"=hd_product.indexOf('"+hd_Product[j]+ "');") };
Browser.msgBox(fin);
//tsheet.getRange(tsheet.getLastRow(), 1, fin.length, fin[0].length).setValues(fin);
The below code - for running it for all the shets is not woeking.
for (i=0;i<sheets.length;i++){
var shtname=sheets[i].getName();
var tsheet=ss.getSheetByName(shtname);
var [header, ...data] = tsheet.getDataRange().getDisplayValues();
for (j=0;j<header.length;j++) {
fin.push("const "+shtname+"_"+header[j]+"=header.indexOf('"+header[j]+ "');") ;
}//for j
Browser.msgBox(fin);
}//for i
//Browser.msgBox(fin);
}
//
//
function process(){
const Product_Code=hd_product.indexOf('Code');
const Product_Item=hd_product.indexOf('Item');
const Product_UOM=hd_product.indexOf('UOM');
const Product_CAT=hd_product.indexOf('CAT');
const Product_Price=hd_product.indexOf('Price');
const Product_Min_Stock=hd_product.indexOf('Min_Stock');
const Product_Lot=hd_product.indexOf('Lot');
const Product_Now_Stock=hd_product.indexOf('Now_Stock');
const Product_Upd_Date=hd_product.indexOf('Upd_Date');
const Product_Vendor1=hd_product.indexOf('Vendor1');
const Product_Vendor2=hd_product.indexOf('Vendor2');
const Product_Vendor3=hd_product.indexOf('Vendor3');
}

Answer 1

A better way is to associate DeveloperMetaData with that column:
const setup = () => {
const sh = SpreadsheetApp.getActive().getSheets()[0];
const setupHeaders = new Map([
['Code', 'A:A'],// associate 'Code' with range A:A/Col 1
['Item', 'B:B'],
]);
setupHeaders.forEach((range, header) =>
sh.getRange(range).addDeveloperMetadata('secretTag', header)
);
};
Once setup, the column can be moved anywhere and the associated metadata will also move. You can then retrieve the current column position using DeveloperMetaDataFinder, even if you change the headers name in the sheet:
const getDevMeta_ = () =>
new Map(
SpreadsheetApp.getActive()
.createDeveloperMetadataFinder()
.withKey('secretTag')
.withLocationType(SpreadsheetApp.DeveloperMetadataLocationType.COLUMN)
.find()
.map(md => [md.getValue(), md.getLocation().getColumn()])
);
const getColumnsForHeaders = (headers = ['Item', 'Code']) => {
const map = getDevMeta_();
return headers.map(header => map.get(header));
};
const test1 = () => console.log(getColumnsForHeaders(['Code', 'Item'])); //returns current location of code and item
References:
Developer metadata guide

Answer 2

function myFunction() {
const ss=SpreadsheetApp.getActive();
const sh=ss.getActiveSheet();
const rg=sh.getDataRange();
const vA=rg.getValues()
//Just learn how to use the next 3 or 4 lines and it's pretty easy you can integrate them into any code
const hA=vA[0];//this is the header row with a [0] index at the end to flatten it out to a single dimension array.
const col={};//returns column from header name
const idx={};//returns index from header name
hA.forEach(function(e,i){col[e]=i+1;idx[e]=i;});//this is the loop to fill in the objects above depending upon whether you want indexes or columns
//Example of how to use them
vA.forEach(function(r,i){}) {
r[idx[headername]];//referring to an index with column header
sh.getRange(i+1,col[headername]).setValue();//reffering to a column with header name
}

Answer 3

How to get a column number by header value
An easy way to return the column number would be the following
function myFunction() {
var searchedHeader = "Hello World";
var column = returnColumn(searchedHeader);
}
function returnColumn(header) {
var ss=SpreadsheetApp.getActiveSpreadsheet();
var tsheet=ss.getSheetByName("Product");
var headers = tsheet.getRange(1, 1, 1, tsheet.getLastColumn()).getValues();
var column = (headers[0].indexOf(header) + 1);
if (column != 0) {
return column;
}
}
You can use the dynamic variable column storing the column number to perform all kind of requests, e.g.
var range = tsheet.getRange(5, column);