Postupy: Přizpůsobení přidávání položek pomocí Windows Forms BindingSource
Při použití BindingSource komponenty k vytvoření vazby model Windows Forms ovládacího prvku ke zdroji dat může být nutné přizpůsobit vytváření nových položek. Tato komponenta BindingSource usnadňuje poskytnutí AddingNew události, která je obvykle vyvolána, když vázané ovládací prvek potřebuje vytvořit novou položku. Obslužná rutina události může poskytnout jakékoli vlastní chování (například volání metody ve webové službě nebo získání nového objektu z objektu pro vytváření tříd).
Poznámka:
Pokud je položka přidána zpracováním AddingNew události, přidání nelze zrušit.
Příklad
Následující příklad ukazuje, jak vytvořit vazbu DataGridView ovládacího prvku k objektu pro vytváření tříd pomocí BindingSource komponenty. Když uživatel klikne na DataGridView nový řádek ovládacího prvku, AddingNew vyvolá se událost. Obslužná rutina události vytvoří nový DemoCustomer objekt, který je přiřazen k AddingNewEventArgs.NewObject vlastnosti. To způsobí, že se nový DemoCustomer objekt přidá do BindingSource seznamu komponent a zobrazí se v novém řádku DataGridView ovládacího prvku.
#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);
}
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;
}
}
}
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
Probíhá kompilace kódu
Tento příklad vyžaduje:
- Odkazy na sestavení System, System.Data, System.Drawing a System.Windows.Forms.
Viz také
Spolupracujte s námi na GitHubu
Zdroj tohoto obsahu najdete na GitHubu, kde můžete také vytvářet a kontrolovat problémy a žádosti o přijetí změn. Další informace najdete v našem průvodci pro přispěvatele.
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