How can I access a TDBGrid column by name instead of by Index?

Question

How can I access a TDBGrid column by name instead of Index?

For example, now I use:

 grdInvoiceItems.Columns[2].Visible := False;

but it would be much better to write something like:

 grdInvoiceItems.Columns['UnitPrice'].Visible := False;

In the mean time I use a for cycle like in:

  for idx := 0 to grdInvoiceItems.Columns.Count - 1 do
    begin
    if (
         (grdInvoiceItems.Columns[idx].FieldName = 'UnitPrice') or
         (grdInvoiceItems.Columns[idx].FieldName = 'Discount') or
         (grdInvoiceItems.Columns[idx].FieldName = 'SecretCode')
       ) then
      grdInvoiceItems.Columns[idx].Visible := False;
    end;

Using colum name is IMO much better tham column index since index is subject to change more often than name.

Any idea on how to encapsulate it better?

Answer 1

You could try something like this:

function ColumnByName(Grid : TDBGrid; const AName : String) : TColumn;
var
  i : Integer;
begin
  Result := Nil;
  for i := 0 to Grid.Columns.Count - 1 do begin
  if (Grid.Columns[i].Field <> Nil) and (CompareText(Grid.Columns[i].FieldName, AName) = 0) then begin
       Result := Grid.Columns[i];
       exit;
     end;
  end;
end;

Of course, if you are using a version of Delphi which is recent enough to support Class Helpers, you could wrap this function into a Class Helper for TDBGrid, like this

type
  TGridHelper = class helper for TDBGrid
    function ColumnByName(const AName : String) : TColumn;
  end;
[...]

function TGridHelper.ColumnByName(const AName: String): TColumn;
var
  i : Integer;
begin
  Result := Nil;
  for i := 0 to Columns.Count - 1 do begin
     if (Columns[i].Field <> Nil) and (CompareText(Columns[i].FieldName, AName) = 0) then begin
       Result := Columns[i];
       exit;
     end;
  end;
end;

Then, you could do this

Col := DBGrid1.ColumnByName('SomeName');

Obviously, you could write a similar function which searches by the column's title, rather than the associated Field's FieldName.