Procedura: condividere dati associati tra form tramite il componente BindingSource
Aggiornamento: novembre 2007
È possibile condividere facilmente i dati tra form tramite il componente BindingSource. Ad esempio, è possibile visualizzare un form di sola lettura che contiene un riepilogo dei dati dell'origine dati e un altro form modificabile che contiene informazioni dettagliate sull'elemento selezionato nell'origine dati. Nell'esempio seguente viene illustrato questo scenario.
Esempio
Nell'esempio di codice seguente viene illustrato come condividere un componente BindingSource e i relativi dati associati tra form. Nell'esempio il componente BindingSource condiviso viene passato al costruttore del form figlio. Il form figlio consente all'utente di modificare i dati relativi all'elemento selezionato nel form principale.
.gif "Nota") Nota: |
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Nell'esempio viene gestito l'evento BindingComplete per il componente BindingSource per assicurarsi che i due form rimangano sincronizzati. Per ulteriori informazioni sul motivo per cui viene eseguita questa operazione, vedere Procedura: garantire la sincronizzazione di più controlli associati alla stessa origine dati. |
Imports System
Imports System.Drawing
Imports System.Windows.Forms
Imports System.Data
Public Class MainForm
Inherits Form
Public Sub New()
End Sub
Private WithEvents bindingSource1 As BindingSource
Private WithEvents button1 As Button
Private Sub MainForm_Load(ByVal sender As Object, ByVal e As EventArgs) _
Handles Me.Load
InitializeData()
End Sub
Private Sub InitializeData()
bindingSource1 = New System.Windows.Forms.BindingSource()
Dim dataset1 As New DataSet()
ClientSize = New System.Drawing.Size(292, 266)
' Some xml data to populate the DataSet with.
' Some xml data to populate the DataSet with.
Dim musicXml As String = "<?xml version='1.0' encoding='UTF-8'?>" & _
"<music><recording><artist>Dave Matthews</artist>" & _
"<cd>Under the Table and Dreaming</cd>" & _
"<releaseDate>1994</releaseDate><rating>3.5</rating></recording>" & _
"<recording><artist>Coldplay</artist><cd>X&Y</cd>" & _
"<releaseDate>2005</releaseDate><rating>4</rating></recording>" & _
"<recording><artist>Dave Matthews</artist>" & _
"<cd>Live at Red Rocks</cd>" & _
"<releaseDate>1997</releaseDate><rating>4</rating></recording>" & _
"<recording><artist>U2</artist>" & _
"<cd>Joshua Tree</cd><releaseDate>1987</releaseDate>" & _
"<rating>5</rating></recording>" & _
"<recording><artist>U2</artist>" & _
"<cd>How to Dismantle an Atomic Bomb</cd>" & _
"<releaseDate>2004</releaseDate><rating>4.5</rating></recording>" & _
"<recording><artist>Natalie Merchant</artist>" & _
"<cd>Tigerlily</cd><releaseDate>1995</releaseDate>" & _
"<rating>3.5</rating></recording>" & _
"</music>"
' Read the xml.
Dim reader As New System.IO.StringReader(musicXml)
dataset1.ReadXml(reader)
' Get a DataView of the table contained in the dataset.
Dim tables As DataTableCollection = dataset1.Tables
Dim view1 As New DataView(tables(0))
' Create a DataGridView control and add it to the form.
Dim datagridview1 As New DataGridView()
datagridview1.ReadOnly = True
datagridview1.AutoGenerateColumns = True
datagridview1.Width = 300
Me.Controls.Add(datagridview1)
bindingSource1.DataSource = view1
datagridview1.DataSource = bindingSource1
datagridview1.Columns.Remove("artist")
datagridview1.Columns.Remove("releaseDate")
' Create and add a button to the form.
button1 = New Button()
button1.AutoSize = True
button1.Text = "Show/Edit Details"
Me.Controls.Add(button1)
button1.Location = New Point(50, 200)
End Sub
' Handle the BindingComplete event to ensure the two forms
' remain synchronized.
Private Sub bindingSource1_BindingComplete(ByVal sender As Object, _
ByVal e As BindingCompleteEventArgs) Handles bindingSource1.BindingComplete
If e.BindingCompleteContext = BindingCompleteContext.DataSourceUpdate _
AndAlso e.Exception Is Nothing Then
e.Binding.BindingManagerBase.EndCurrentEdit()
End If
End Sub
' The detailed form will be shown when the button is clicked.
Private Sub button1_Click(ByVal sender As Object, ByVal e As EventArgs) _
Handles button1.Click
Dim detailForm As New DetailForm(bindingSource1)
detailForm.Show()
End Sub
<STAThread()> _
Shared Sub Main()
Application.EnableVisualStyles()
Application.Run(New MainForm())
End Sub
End Class
' The detail form class.
Public Class DetailForm
Inherits Form
Private formDataSource As BindingSource
' The constructor takes a BindingSource object.
Public Sub New(ByVal dataSource As BindingSource)
formDataSource = dataSource
Me.ClientSize = New Size(240, 200)
Dim textBox1 As New TextBox()
Me.Text = "Selection Details"
textBox1.Width = 220
Dim textBox2 As New TextBox()
Dim textBox3 As New TextBox()
Dim textBox4 As New TextBox()
textBox4.Width = 30
textBox3.Width = 50
' Associate each text box with a column from the data source.
textBox1.DataBindings.Add("Text", formDataSource, "cd", _
True, DataSourceUpdateMode.OnPropertyChanged)
textBox2.DataBindings.Add("Text", formDataSource, "artist", True)
textBox3.DataBindings.Add("Text", formDataSource, "releaseDate", True)
textBox4.DataBindings.Add("Text", formDataSource, "rating", True)
textBox1.Location = New Point(10, 10)
textBox2.Location = New Point(10, 40)
textBox3.Location = New Point(10, 80)
textBox4.Location = New Point(10, 120)
Me.Controls.AddRange(New Control() {textBox1, textBox2, textBox3, _
textBox4})
End Sub
End Class
using System;
using System.Drawing;
using System.Windows.Forms;
using System.Data;
namespace BindingSourceMultipleForms
{
public class MainForm : Form
{
public MainForm()
{
this.Load += new EventHandler(MainForm_Load);
}
private BindingSource bindingSource1;
private Button button1;
private void MainForm_Load(object sender, EventArgs e)
{
InitializeData();
}
private void InitializeData()
{
bindingSource1 = new System.Windows.Forms.BindingSource();
// Handle the BindingComplete event to ensure the two forms
// remain synchronized.
bindingSource1.BindingComplete +=
new BindingCompleteEventHandler(bindingSource1_BindingComplete);
ClientSize = new System.Drawing.Size(292, 266);
DataSet dataset1 = new DataSet();
// Some xml data to populate the DataSet with.
string musicXml =
"<?xml version='1.0' encoding='UTF-8'?>" +
"<music>" +
"<recording><artist>Dave Matthews</artist>" +
"<cd>Under the Table and Dreaming</cd>" +
"<releaseDate>1994</releaseDate><rating>3.5</rating></recording>" +
"<recording><artist>Coldplay</artist><cd>X&Y</cd>" +
"<releaseDate>2005</releaseDate><rating>4</rating></recording>" +
"<recording><artist>Dave Matthews</artist>" +
"<cd>Live at Red Rocks</cd>" +
"<releaseDate>1997</releaseDate><rating>4</rating></recording>" +
"<recording><artist>U2</artist>" +
"<cd>Joshua Tree</cd><releaseDate>1987</releaseDate>" +
"<rating>5</rating></recording>" +
"<recording><artist>U2</artist>" +
"<cd>How to Dismantle an Atomic Bomb</cd>" +
"<releaseDate>2004</releaseDate><rating>4.5</rating></recording>" +
"<recording><artist>Natalie Merchant</artist>" +
"<cd>Tigerlily</cd><releaseDate>1995</releaseDate>" +
"<rating>3.5</rating></recording>" +
"</music>";
// Read the xml.
System.IO.StringReader reader = new System.IO.StringReader(musicXml);
dataset1.ReadXml(reader);
// Get a DataView of the table contained in the dataset.
DataTableCollection tables = dataset1.Tables;
DataView view1 = new DataView(tables[0]);
// Create a DataGridView control and add it to the form.
DataGridView datagridview1 = new DataGridView();
datagridview1.ReadOnly = true;
datagridview1.AutoGenerateColumns = true;
datagridview1.Width = 300;
this.Controls.Add(datagridview1);
bindingSource1.DataSource = view1;
datagridview1.DataSource = bindingSource1;
datagridview1.Columns.Remove("artist");
datagridview1.Columns.Remove("releaseDate");
// Create and add a button to the form.
button1 = new Button();
button1.AutoSize = true;
button1.Text = "Show/Edit Details";
this.Controls.Add(button1);
button1.Location = new Point(50, 200);
button1.Click += new EventHandler(button1_Click);
}
// Handle the BindingComplete event to ensure the two forms
// remain synchronized.
private void bindingSource1_BindingComplete(object sender, BindingCompleteEventArgs e)
{
if (e.BindingCompleteContext == BindingCompleteContext.DataSourceUpdate
&& e.Exception == null)
e.Binding.BindingManagerBase.EndCurrentEdit();
}
// The detailed form will be shown when the button is clicked.
private void button1_Click(object sender, EventArgs e)
{
DetailForm detailForm = new DetailForm(bindingSource1);
detailForm.Show();
}
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.Run(new MainForm());
}
}
// The detail form class.
public class DetailForm : Form
{
private BindingSource formDataSource;
// The constructor takes a BindingSource object.
public DetailForm(BindingSource dataSource)
{
formDataSource = dataSource;
this.ClientSize = new Size(240, 200);
TextBox textBox1 = new TextBox();
this.Text = "Selection Details";
textBox1.Width = 220;
TextBox textBox2 = new TextBox();
TextBox textBox3 = new TextBox();
TextBox textBox4 = new TextBox();
textBox4.Width = 30;
textBox3.Width = 50;
// Associate each text box with a column from the data source.
textBox1.DataBindings.Add("Text", formDataSource, "cd", true, DataSourceUpdateMode.OnPropertyChanged);
textBox2.DataBindings.Add("Text", formDataSource, "artist", true);
textBox3.DataBindings.Add("Text", formDataSource, "releaseDate", true);
textBox4.DataBindings.Add("Text", formDataSource, "rating", true);
textBox1.Location = new Point(10, 10);
textBox2.Location = new Point(10, 40);
textBox3.Location = new Point(10, 80);
textBox4.Location = new Point(10, 120);
this.Controls.AddRange(new Control[] { textBox1, textBox2, textBox3, textBox4 });
}
}
}
Compilazione del codice
Per questo esempio sono necessari i seguenti requisiti:
- Riferimenti agli assembly System, System.Windows.Forms, System.Drawing, System.Data e System.Xml.
Per informazioni sulla generazione di questo esempio dalla riga di comando per Visual Basic o Visual C#, vedere Compilazione dalla riga di comando (Visual Basic) o Compilazione dalla riga di comando con csc.exe. È anche possibile generare questo esempio in Visual Studio incollando il codice in un nuovo progetto.
Vedere anche
Attività
Procedura: gestire gli errori e le eccezioni che si verificano con l'associazione dati