Perform Vlookup from sheet 1 to sheet 2 and pass a matching value found in sheet 2 to external API - api

Question

I have Sheet 1 which contains a bunch of data including names of users. Sheet 2 contains users' names with their ID. I want to do some kind of mapping and I am not sure how to go about it.
Ideally, I would like to read a range of rows, say AA: AE and match the names in sheet 1 with the ones in sheet 2 with ID, and then POST the ID in sheet 2 to an external API.
Here is the code:
function getData(startRow, endRow) {
var ss = SpreadsheetApp.getActive();
//Temporary calc sheet
var calcSheet = ss.getSheetByName("CALC_SHEET");
//Clear data range from previous calculations
calcSheet.getDataRange().clear();
//Clear data range from previous calculations
calcSheet.getDataRange().clear();
//formula template
var formulaTemplate = '{ArrayFormula(IFERROR(VLOOKUP(Form Responses 1!AF1{{startRow}}:AL{{endRow}},{UserID mapping!B1:B132,user_ids!C1:C132},2,false),"")),QUERY(UserID mapping!A{{startRow}}:C{{endRow}}, "select *")}';
//insert startRow and endRow into the formula
var formula = formulaTemplate.split("{{startRow}}").join(startRow).split("{{endRow}}").join(endRow);
//insert formula into the helper sheet
calcSheet.getRange(1, 1).setFormula(formula);
//write changes to the spreadsheet
SpreadsheetApp.flush();
var values = calcSheet.getDataRange().getValues();
//overwrite formula with values
calcSheet.getDataRange().setValues(values);
return values;
}

Answer 1

Here's a quick example to get you up and running. Below is my sheet with mock user data (not sorted):
The 2nd sheet contains user names mapped to their respective ids:
Step 1
The task is basically to match unique user id from the 'user_ids' sheet to each row in 'user_data' table.
=ArrayFormula(IFERROR(VLOOKUP(user_data!A1:A10,{user_ids!B1:B10,user_ids!A1:A10},2,false),""))
Note that because VLOOKUP uses the first column as the index column, I had to reverse the order of columns in the user_ids sheet so that column B (name column) comes first. This function returns user ids for every single row in 'user_data' (in correct order).
The last step is to display other columns from user data. Final formula
={ArrayFormula(IFERROR(VLOOKUP(user_data!A1:A10,{user_ids!B1:B10,user_ids!A1:A10},2,false),"")),QUERY(user_data!A1:C10, "select *")}
Result:
What if you want to do the same thing programmatically? You can use the same formulas! The downside is that you may need to create a temporary sheet for calculations - think of it as your cache or database. Of course, you can hide the helper sheet or delete it when it's not in use.
Below is the function that utilizes the above approach to return specified rows matched with their ids. Of course, you can still make it better by passing column indexes and handling errors
function getData(startRow, endRow) {
var ss = SpreadsheetApp.getActive();
//Temporary calc sheet
var calcSheet = ss.getSheetByName("calc_sheet");
//Clear data range from previous calculations
calcSheet.getDataRange().clear();
//formula template
var formulaTemplate = '{ArrayFormula(IFERROR(VLOOKUP(user_data!A{{startRow}}:A{{endRow}},{user_ids!B1:B10,user_ids!A1:A10},2,false),"")),QUERY(user_data!A{{startRow}}:C{{endRow}}, "select *")}';
//insert startRow and endRow into the formula
var formula = formulaTemplate.split("{{startRow}}").join(startRow).split("{{endRow}}").join(endRow);
//insert formula into the helper sheet
calcSheet.getRange(1, 1).setFormula(formula);
//write changes to the spreadsheet
SpreadsheetApp.flush();
var values = calcSheet.getDataRange().getValues();
//overwrite formula with values
calcSheet.getDataRange().setValues(values);
return values;
}