Comparing DBgrid and ClientDataSet field names

Question

How to compare field names of clientdataset and dbgrid? For example check every field as visible in clientdataset if it exists in dgbrid?

Answer 1

Solution:

for i := 0 to cds.Fields.Count-1 do begin
   for j := 0 to grid.Columns.Count-1 do begin
       if cds.Fields[i].FieldName = grid.Columns[j].FieldName then begin
          ShowMessage('Field: ' + cds.Fields[i].FieldName);
          Break;
       end;
   end;
end;

Working example:

unit frmMain;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, DB, DBClient, Grids, DBGrids;

type
  TForm1 = class(TForm)
    btnCheck: TButton;
    ds: TDataSource;
    cds: TClientDataSet;
    grid: TDBGrid;
    procedure btnCheckClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.btnCheckClick(Sender: TObject);
var
   i, j: Integer;
begin
   // Controls
   if cds.Active then cds.Close;
   ds.DataSet := cds;
   grid.DataSource := ds;

   // Dataset. Create dataset with three fields.
   cds.FieldDefs.Clear;
   cds.FieldDefs.Add('FIELD1', ftString, 10, False);
   cds.FieldDefs.Add('FIELD2', ftString, 20, False);
   cds.FieldDefs.Add('FIELD3', ftString, 30, False);
   try
      cds.CreateDataSet;
      cds.Open;
   except
      on E: Exception do begin
         ShowMessage('Error: ' + E.Message);
         Exit;
      end{on};
   end{try};

   // Grid. Set grid with one column.
   grid.Columns.Clear;
   with grid.Columns.Add do begin
      FieldName := 'FIELD1';
   end{with};

   // Check every field
   for i := 0 to cds.Fields.Count-1 do begin
      for j := 0 to grid.Columns.Count-1 do begin
          if cds.Fields[i].FieldName = grid.Columns[j].FieldName then begin
             ShowMessage('Field: ' + cds.Fields[i].FieldName);
             Break;
          end{if};
      end{if};
   end{if};
end;

end.

Notes:

You can check TField.Visible and/or TColumn.Visible properties.