[andrecrp77]

Hola.

Sigue la solución que encontré para continuar utilizando los eventos Before / Afterfieldchange en Delphi Tokyo.
Estamos en el camino correcto, algún ajuste?

Código Delphi [-]
unit utilclientdataset;

Interface

uses

  DB, DBClient;

type

  TFieldAfterChangeEvent = procedure (Field :TField; PrevValue :Variant) Of Object;
  TFieldBeforeChangeEvent = procedure (Field :TField; NewValue :Variant) Of Object;

  TSysClientDataSet = Class (TClientDataSet)
  private
    FAfterFieldChange :TFieldAfterChangeEvent;
    FBeforeFieldChange :TFieldBeforeChangeEvent;
  protected
    TempFieldData:TValueBuffer;
    procedure NativeValue(Const Field :TField; ABuffer :TValueBuffer; var ANewValue:Variant; var ANewValueBuffer :TValueBuffer);
    procedure SetFieldData(Field :TField; Buffer :TValueBuffer);override;
  public
    function GetFieldData(Field: TField; var Buffer: TValueBuffer): Boolean;override;
  published
    property AfterFieldChange :TFieldAfterChangeEvent Read FAfterFieldChange Write FAfterFieldChange;
    property BeforeFieldChange :TFieldBeforeChangeEvent Read FBeforeFieldChange Write FBeforeFieldChange;
  end;

implementation

type
  TFieldAccess = Class (TField);

function TSysClientDataSet.GetFieldData(Field: TField; var Buffer: TValueBuffer): Boolean;
begin
  if TempFieldData=nil then
    Result:=Inherited GetFieldData(Field,Buffer)
  else
  begin
    Result:=TempFieldData <> Nil;
    if Result and (Buffer <> Nil) then
      TPlatformValueBuffer.Copy(TempFieldData,0,Buffer,Field.DataSize);
  end;
end;

procedure TSysClientDataSet.NativeValue(Const Field :TField; ABuffer :TValueBuffer; var ANewValue:Variant; var ANewValueBuffer :TValueBuffer);
begin
  TempFieldData := TPlatformValueBuffer.CreateValueBuffer(Field.DataSize);
  try
    TPlatformValueBuffer.Copy(ABuffer,0,TempFieldData,Field.DataSize);
    TPlatformValueBuffer.Copy(ABuffer,0,ANewValueBuffer,Field.DataSize);
    ANewValue:=Field.Value;
  finally
    TempFieldData:=Nil;
  end;
end;

procedure TSysClientDataSet.SetFieldData(Field :TField; Buffer :TValueBuffer);
var
  NewValue, PrevValue:Variant;
  NewValueBuffer:TValueBuffer;
begin
  if State in [dsEdit, dsInsert] then
  begin
    NewValueBuffer:= TPlatformValueBuffer.CreateValueBuffer(Field.DataSize);
    try
      NativeValue (Field, Buffer, NewValue, NewValueBuffer);
      if NewValue <> Field.Value then
      begin
        if Assigned (BeforeFieldChange) Then
          BeforeFieldChange (Field, NewValue);
        PrevValue := Field.Value;
        inherited SetFieldData (Field, NewValueBuffer);
        if Assigned (AfterFieldChange) then
          AfterFieldChange (Field, PrevValue);
        Exit;
      end;
    finally
      NewValueBuffer:=nil;
    end;
  end;
  inherited SetFieldData (Field, Buffer);
end;

end.