Cómo: Personalizar la forma de agregar elementos con el control BindingSource de formularios Windows Forms
Cuando se utiliza un componente BindingSource para enlazar un control de formularios Windows Forms a un origen de datos, puede que sea necesario personalizar la creación de nuevos elementos. El componente BindingSource lo realiza de forma sencilla proporcionando el evento AddingNew, que normalmente se produce cuando el control enlazado necesita crear un elemento nuevo. El controlador de eventos puede proporcionar el comportamiento personalizado necesario (por ejemplo, llamar a un método de un servicio Web u obtener un nuevo objeto de un generador de clases).
Nota
Cuando un elemento se agrega controlando el evento AddingNew, no se puede cancelar esta acción.
Ejemplo
El ejemplo siguiente muestra cómo enlazar un control DataGridView a un generador de clases utilizando un componente BindingSource. Cuando el usuario hace clic en la nueva fila del control DataGridView, se produce el evento AddingNew. El controlador de eventos crea un nuevo objeto DemoCustomer asignado a la propiedad AddingNewEventArgs.NewObject. Esto hace que el nuevo objeto DemoCustomer se agregue a la lista del componente BindingSource y que se muestre en la nueva fila del control DataGridView.
Imports System
Imports System.Collections.Generic
Imports System.ComponentModel
Imports System.Data
Imports System.Drawing
Imports System.Data.SqlClient
Imports System.Windows.Forms
' This form demonstrates using a BindingSource to provide
' data from a collection of custom types to a DataGridView control.
Public Class Form1
Inherits System.Windows.Forms.Form
' This is the BindingSource that will provide data for
' the DataGridView control.
Private WithEvents customersBindingSource As New BindingSource()
' This is the DataGridView control that will display our data.
Private customersDataGridView As New DataGridView()
' Set up the StatusBar for displaying ListChanged events.
Private status As New StatusBar()
Public Sub New()
' Set up the form.
Me.Size = New Size(800, 800)
AddHandler Me.Load, AddressOf Form1_Load
Me.Controls.Add(status)
' Set up the DataGridView control.
Me.customersDataGridView.Dock = DockStyle.Fill
Me.Controls.Add(customersDataGridView)
End Sub
Private Sub Form1_Load( _
ByVal sender As System.Object, _
ByVal e As System.EventArgs)
' Add a DemoCustomer to cause a row to be displayed.
Me.customersBindingSource.AddNew()
' Bind the BindingSource to the DataGridView
' control's DataSource.
Me.customersDataGridView.DataSource = Me.customersBindingSource
End Sub
' This event handler provides custom item-creation behavior.
Private Sub customersBindingSource_AddingNew( _
ByVal sender As Object, _
ByVal e As AddingNewEventArgs) _
Handles customersBindingSource.AddingNew
e.NewObject = DemoCustomer.CreateNewCustomer()
End Sub
' This event handler detects changes in the BindingSource
' list or changes to items within the list.
Private Sub customersBindingSource_ListChanged( _
ByVal sender As Object, _
ByVal e As ListChangedEventArgs) _
Handles customersBindingSource.ListChanged
status.Text = e.ListChangedType.ToString()
End Sub
<STAThread()> _
Shared Sub Main()
Application.EnableVisualStyles()
Application.Run(New Form1())
End Sub
End Class
' This class implements a simple customer type.
Public Class DemoCustomer
' These fields hold the values for the public properties.
Private idValue As Guid = Guid.NewGuid()
Private customerName As String = String.Empty
Private companyNameValue As String = String.Empty
Private phoneNumberValue As String = String.Empty
' The constructor is private to enforce the factory pattern.
Private Sub New()
customerName = "no data"
companyNameValue = "no data"
phoneNumberValue = "no data"
End Sub
' This is the public factory method.
Public Shared Function CreateNewCustomer() As DemoCustomer
Return New DemoCustomer()
End Function
' This property represents an ID, suitable
' for use as a primary key in a database.
Public ReadOnly Property ID() As Guid
Get
Return Me.idValue
End Get
End Property
Public Property CompanyName() As String
Get
Return Me.companyNameValue
End Get
Set(ByVal value As String)
Me.companyNameValue = Value
End Set
End Property
Public Property PhoneNumber() As String
Get
Return Me.phoneNumberValue
End Get
Set(ByVal value As String)
Me.phoneNumberValue = Value
End Set
End Property
End Class
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Data.SqlClient;
using System.Windows.Forms;
// This form demonstrates using a BindingSource to provide
// data from a collection of custom types to a DataGridView control.
public class Form1 : System.Windows.Forms.Form
{
// This is the BindingSource that will provide data for
// the DataGridView control.
private BindingSource customersBindingSource = new BindingSource();
// This is the DataGridView control that will display our data.
private DataGridView customersDataGridView = new DataGridView();
// Set up the StatusBar for displaying ListChanged events.
private StatusBar status = new StatusBar();
public Form1()
{
// Set up the form.
this.Size = new Size(800, 800);
this.Load += new EventHandler(Form1_Load);
this.Controls.Add(status);
// Set up the DataGridView control.
this.customersDataGridView.Dock = DockStyle.Fill;
this.Controls.Add(customersDataGridView);
// Attach an event handler for the AddingNew event.
this.customersBindingSource.AddingNew +=
new AddingNewEventHandler(customersBindingSource_AddingNew);
// Attach an event handler for the ListChanged event.
this.customersBindingSource.ListChanged +=
new ListChangedEventHandler(customersBindingSource_ListChanged);
}
private void Form1_Load(System.Object sender, System.EventArgs e)
{
// Add a DemoCustomer to cause a row to be displayed.
this.customersBindingSource.AddNew();
// Bind the BindingSource to the DataGridView
// control's DataSource.
this.customersDataGridView.DataSource =
this.customersBindingSource;
}
// This event handler provides custom item-creation behavior.
void customersBindingSource_AddingNew(
object sender,
AddingNewEventArgs e)
{
e.NewObject = DemoCustomer.CreateNewCustomer();
}
// This event handler detects changes in the BindingSource
// list or changes to items within the list.
void customersBindingSource_ListChanged(
object sender,
ListChangedEventArgs e)
{
status.Text = e.ListChangedType.ToString();
}
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.Run(new Form1());
}
}
// This class implements a simple customer type.
public class DemoCustomer
{
// These fields hold the values for the public properties.
private Guid idValue = Guid.NewGuid();
private string customerName = String.Empty;
private string companyNameValue = String.Empty;
private string phoneNumberValue = String.Empty;
// The constructor is private to enforce the factory pattern.
private DemoCustomer()
{
customerName = "no data";
companyNameValue = "no data";
phoneNumberValue = "no data";
}
// This is the public factory method.
public static DemoCustomer CreateNewCustomer()
{
return new DemoCustomer();
}
// This property represents an ID, suitable
// for use as a primary key in a database.
public Guid ID
{
get
{
return this.idValue;
}
}
public string CompanyName
{
get
{
return this.companyNameValue;
}
set
{
this.companyNameValue = value;
}
}
public string PhoneNumber
{
get
{
return this.phoneNumberValue;
}
set
{
this.phoneNumberValue = value;
}
}
}
#using <System.dll>
#using <System.Drawing.dll>
#using <System.Windows.Forms.dll>
using namespace System;
using namespace System::ComponentModel;
using namespace System::Drawing;
using namespace System::Globalization;
using namespace System::Windows::Forms;
namespace DataConnectorAddingNewExample
{
// This class implements a simple customer type.
public ref class DemoCustomer
{
private:
// These fields hold the values for the public properties.
Guid idValue;
String^ customerName;
String^ companyNameValue;
String^ phoneNumberValue;
// The constructor is private to enforce the factory pattern.
DemoCustomer()
{
idValue = Guid::NewGuid();
customerName = String::Empty;
companyNameValue = String::Empty;
phoneNumberValue = String::Empty;
customerName = "no data";
companyNameValue = "no data";
phoneNumberValue = "no data";
}
public:
// This is the public factory method.
static DemoCustomer^ CreateNewCustomer()
{
return gcnew DemoCustomer;
}
property Guid ID
{
// This property represents an ID, suitable
// for use as a primary key in a database.
Guid get()
{
return this->idValue;
}
}
property String^ CompanyName
{
String^ get()
{
return this->companyNameValue;
}
void set(String^ value)
{
this->companyNameValue = value;
}
}
property String^ PhoneNumber
{
String^ get()
{
return this->phoneNumberValue;
}
void set(String^ value)
{
this->phoneNumberValue = value;
}
}
};
// This form demonstrates using a BindingSource to provide
// data from a collection of custom types
// to a DataGridView control.
public ref class MainForm: public System::Windows::Forms::Form
{
private:
// This is the BindingSource that will provide data for
// the DataGridView control.
BindingSource^ customersBindingSource;
// This is the DataGridView control
// that will display our data.
DataGridView^ customersDataGridView;
// Set up the StatusBar for displaying ListChanged events.
StatusBar^ status;
public:
MainForm()
{
customersBindingSource = gcnew BindingSource;
customersDataGridView = gcnew DataGridView;
status = gcnew StatusBar;
// Set up the form.
this->Size = System::Drawing::Size(600, 400);
this->Text = "BindingSource.AddingNew sample";
this->Load +=
gcnew EventHandler(this, &MainForm::OnMainFormLoad);
this->Controls->Add(status);
// Set up the DataGridView control.
this->customersDataGridView->Dock = DockStyle::Fill;
this->Controls->Add(this->customersDataGridView);
// Attach an event handler for the AddingNew event.
this->customersBindingSource->AddingNew +=
gcnew AddingNewEventHandler(this,
&MainForm::OnCustomersBindingSourceAddingNew);
// Attach an event handler for the ListChanged event.
this->customersBindingSource->ListChanged +=
gcnew ListChangedEventHandler(this,
&MainForm::OnCustomersBindingSourceListChanged);
}
private:
void OnMainFormLoad(Object^ sender, EventArgs^ e)
{
// Add a DemoCustomer to cause a row to be displayed.
this->customersBindingSource->AddNew();
// Bind the BindingSource to the DataGridView
// control's DataSource.
this->customersDataGridView->DataSource =
this->customersBindingSource;
}
// This event handler provides custom item-creation behavior.
void OnCustomersBindingSourceAddingNew(Object^ sender,
AddingNewEventArgs^ e)
{
e->NewObject = DemoCustomer::CreateNewCustomer();
}
// This event handler detects changes in the BindingSource
// list or changes to items within the list.
void OnCustomersBindingSourceListChanged(Object^ sender,
ListChangedEventArgs^ e)
{
status->Text = Convert::ToString(e->ListChangedType,
CultureInfo::CurrentCulture);
}
};
}
[STAThread]
int main()
{
Application::EnableVisualStyles();
Application::Run(gcnew DataConnectorAddingNewExample::MainForm);
}
Compilar el código
Este ejemplo requiere:
- Referencias a los ensamblados System, System.Data, System.Drawing y System.Windows.Forms.
Para obtener información sobre la compilación de este ejemplo desde la línea de comandos de Visual Basic o Visual C#, vea Generar desde la línea de comandos (Visual Basic) o Compilar la línea de comandos con csc.exe. También puede compilar este ejemplo en Visual Studio pegando el código en un proyecto nuevo. Para obtener más información, vea Cómo: Compilar y ejecutar un ejemplo de código completo de formularios Windows Forms utilizando Visual Studio y Cómo: Compilar y ejecutar un ejemplo de código completo de formularios Windows Forms utilizando Visual Studio y Cómo: Compilar y ejecutar un ejemplo de código completo de formularios Windows Forms utilizando Visual Studio y Cómo: Compilar y ejecutar un ejemplo de código completo de Windows Forms en Visual Studio y Cómo: Compilar y ejecutar un ejemplo de código completo de Windows Forms en Visual Studio.
Vea también
Tareas
Cómo: Enlazar un control de Windows Forms a un tipo