Criando um DBDateTimePicker: DateTimePicker - Parte 1

Olá galera, nesta Quick Tips, irei mostrar, basicamente, como podemos modificar nossos componentes do Delphi, veja este poderoso recurso que podemos fazer com um simples DateTimePicker, fazendo com que o mesmo possa exibir valores de nosso banco de dados, assim como o DBEdit.

Vamos inicialmente criar uma unit, e salvar a mesma como DBDateTimePicker.pas .

Na mesma vamos agora declarar a Classe TDateTimePicker

unit DBDateTimePicker;

interface

uses

SysUtils, Classes, Controls, ComCtrls, DBCtrls, DB, Messages;

type

TDateTimePicker = class(ComCtrls.TDateTimePicker)

private

{ Private declarations }

FDataLink: TFieldDataLink;

function GetDataField: string;

function GetDataSource: TDataSource;

procedure SetDataField(const Value: string);

procedure SetDataSource(const Value: TDataSource);

procedure DataChange(Sender: TObject);

protected

{ Protected declarations }

procedure UpdateData(Sender: TObject);

procedure Change; override;

procedure CMExit(var Msg: TMessage); message CM_EXIT;

public

{ Public declarations }

constructor Create(AOwner: TComponent); override;

destructor Destroy; override;

published

{ Published declarations }

property DataField: string read GetDataField write SetDataField;

property DataSource: TDataSource read GetDataSource write SetDataSource;

end;

implementation

uses

Variants;

{ TDBDateTimePicker }

procedure TDateTimePicker.Change;

begin

if not FDataLink.Editing then

FDataLink.Edit;

FDataLink.Modified;

inherited;

end;

procedure TDateTimePicker.CMExit(var Msg: TMessage);

begin

try

FDataLink.UpdateRecord;

except

on Exception do

SetFocus;

end;

end;

constructor TDateTimePicker.Create(AOwner: TComponent);

begin

inherited;

FDataLink:=TFieldDataLink.Create;

FDataLink.OnDataChange := DataChange;

FDataLink.OnUpdateData := UpdateData;

Self.Date := Now;

end;

procedure TDateTimePicker.DataChange(Sender: TObject);

begin

if Assigned(FDataLink.DataSource) and Assigned(FDataLink.Field) then

begin

if FDataLink.Field.AsDateTime <> StrToDate( '30/12/1899' ) then

Self.Date:=FDataLink.Field.AsDateTime

else

Self.Date := Now;

end;

end;

destructor TDateTimePicker.Destroy;

begin

FDataLink.Free;

inherited;

end;

function TDateTimePicker.GetDataField: string;

begin

Result:=FDataLink.FieldName;

end;

function TDateTimePicker.GetDataSource: TDataSource;

begin

Result:=FDataLink.DataSource;

end;

procedure TDateTimePicker.SetDataField(const Value: string);

begin

FDataLink.FieldName := Value;

end;

procedure TDateTimePicker.SetDataSource(const Value: TDataSource);

begin

FDataLink.DataSource := Value;

end;

procedure TDateTimePicker.UpdateData(Sender: TObject);

begin

FDataLink.Field.AsDateTime := Self.Date;

end;

end.

Fico por aqui até a próxima parte.

Um abraço

Wesley Y

wyamazack@rwsolution.com.br