Delphi save data in StringGrid to Json file

Question

Iam having a stringGrid, The fields in First row are from CSV and in Second row are ColumnNames from a table in DB.

Now after click on save btn it should create me a Json file like below

{
"GHARGA": "GHARGA",
"SELLINGPRICE1": "SELLPRICE1",
"SELLPRICE2": "SELLPRICE2",
"SELLPRICE3": "SELLPRICE3",
"PCODE": "PCODE"
}

I tried this like this:

 procedure TfrmMapping.btnsaveClick(Sender: TObject);
var
  Dat1: TStringList;
  i: Integer;
  lJsonObj: TJSONObject;
begin
  lJsonObj := TJSONObject.Create;

  Dat1 := TStringList.Create;

  if btnsave.Caption = 'Save' then
  begin
     for i := 0 to StrGrdCsv.RowCount - 1 do
     begin
     Dat1.AddStrings(StrGrdCsv.Rows[i]);
     end;

    for i := Dat1.Count - 1 Downto StrGrdCsv.ColCount do
    begin
      lJsonObj.AddPair(TJSONPair.Create(TJSONString.Create(Dat1.Strings[i]),
      TJSONString.Create(Dat1.Strings[i])));
    end;

    TFile.WriteAllText(cmbBXDBTables.Text + '.json', lJsonObj.ToString);
    btnsave.Caption := 'Load Data';
      end;
      end;

but it is creating like

 {
    "GHARGA": "GHARGA",
    "SELLPRICE1": "SELLPRICE1",
    "SELLPRICE2": "SELLPRICE2",
    "SELLPRICE3": "SELLPRICE3",
    "PCODE": "PCODE"
     }

Answer 1

Modifed the Code as per suggestions by @DavidHeffemann and @RemyLeebeau

procedure TfrmMapping.btnsaveClick(Sender: TObject);
var
  i: Integer;
  lJsonObj: TJSONObject;
begin
  lJsonObj := TJSONObject.Create;

  if btnsave.Caption = 'Save' then
  begin
    for i := 0 to StrGrdCsv.ColCount do
    begin
      lJsonObj.AddPair(StrGrdCsv.Cells[i, 0], StrGrdCsv.Cells[i, 1]);
    end;
    TFile.WriteAllText(cmbBXDBTables.Text + '.json', lJsonObj.ToString);
    btnsave.Caption := 'Load Data';
  end;
end;

Modified the For loop and made it work using Cells of String Grid.

Thank You, @DavidHeffemann and @RemyLeebeau for your suggestions.