unit Unit2;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, FireDAC.Stan.Intf, FireDAC.Stan.Option, FireDAC.Stan.Param,
  FireDAC.Stan.Error, FireDAC.DatS, FireDAC.Phys.Intf, FireDAC.DApt.Intf, Data.DB,
  FireDAC.Comp.DataSet, FireDAC.Comp.Client;

type

  TExFDMemTable = class(TFDMemTable)
  private
    FOnBeforeCreateFields: TProc<TDataSet>;
  protected
    procedure CreateFields; override;
  public
    property OnBeforeCreateFields: TProc<TDataSet> read FOnBeforeCreateFields write
        FOnBeforeCreateFields;
  end;

  TFDMemTable = class(TExFDMemTable)
  end;

  TForm2 = class(TForm)
    FDMemTable1: TFDMemTable;
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form2: TForm2;

implementation

{$R *.dfm}

procedure TForm2.FormCreate(Sender: TObject);
var
  SomeDataSet: TFDMemTable;
begin
  SomeDataSet := TFDMemTable.Create(Self);
  with SomeDataSet do
    begin
      with FieldDefs do
        begin
          Clear;
          Add('ID', ftInteger);
          Add('Name', ftString);
          Add('CurrDate', ftDateTime);
        end;
      Active := True;
      AppendRecord([0, 'DDD', '18.01.2016']);
      AppendRecord([1, 'SSS', '17.01.2016']);
      AppendRecord([2, 'AAA', '19.01.2016']);
      AppendRecord([3, 'VVV', '20.01.2016']);
    end;

  FDMemTable1.OnBeforeCreateFields := procedure(ADataSet: TDataSet)
    begin
      if ADataSet.FieldDefs.IndexOf('Edited') = -1 then
        ADataSet.FieldDefs.Add('Edited', ftBoolean);
    end;
  FDMemTable1.CopyDataSet(SomeDataSet, [coStructure, coRestart, coAppend]);

  FDMemTable1.First;
  while not FDMemTable1.Eof do
    begin
      FDMemTable1.Edit;
      FDMemTable1.FieldByName('Edited').AsBoolean := False;
      FDMemTable1.Post;
      FDMemTable1.Next;
    end;

  SomeDataSet.Free;
end;

procedure TExFDMemTable.CreateFields;
begin
  if Assigned(FOnBeforeCreateFields) then
    FOnBeforeCreateFields(Self);
  inherited CreateFields;
end;


end.