Guide pratique pour gérer les erreurs et les exceptions qui se produisent avec la liaison de données
Souvent, les exceptions et les erreurs se produisent sur les objets métier sous-jacents lorsque vous les liez aux contrôles. Vous pouvez intercepter ces erreurs et exceptions, puis récupérer ou transmettre les informations d’erreur à l’utilisateur en gérant l’événement BindingComplete pour un Bindingparticulier, BindingSourceou CurrencyManager composant.
Exemple
Cet exemple de code montre comment gérer les erreurs et exceptions qui se produisent pendant une opération de liaison de données. Il montre comment intercepter des erreurs en gérant l’événement Binding.BindingComplete des objets Binding. Pour intercepter les erreurs et les exceptions en gérant cet événement, vous devez activer la mise en forme de la liaison. Vous pouvez activer la mise en forme lorsque la liaison est construite ou ajoutée à la collection de liaisons, ou en définissant la propriété FormattingEnabled sur true.
// Represents a business object that throws exceptions when
// invalid values are entered for some of its properties.
public ref class Part
{
private:
String^ name;
int number;
double price;
public:
Part(String^ name, int number, double price)
{
PartName = name;
PartNumber = number;
PartPrice = price;
}
property String^ PartName
{
String^ get()
{
return name;
}
void set(String^ value)
{
if (value->Length <= 0)
{
throw gcnew Exception(
"Each part must have a name.");
}
else
{
name = value;
}
}
}
property double PartPrice
{
double get()
{
return price;
}
void set(double value)
{
price = value;
}
}
property int PartNumber
{
int get()
{
return number;
}
void set(int value)
{
if (value < 100)
{
throw gcnew Exception(
"Invalid part number." \
"Part numbers must be " \
"greater than 100.");
}
else
{
number = value;
}
}
}
};
ref class MainForm: public Form
{
private:
BindingSource^ bindingSource;
TextBox^ partNameTextBox;
TextBox^ partNumberTextBox;
TextBox^ partPriceTextBox;
public:
MainForm()
{
bindingSource = gcnew BindingSource;
partNameTextBox = gcnew TextBox;
partNumberTextBox = gcnew TextBox;
partPriceTextBox = gcnew TextBox;
//Set up the textbox controls.
this->partNameTextBox->Location = Point(82, 13);
this->partNameTextBox->TabIndex = 1;
this->partNumberTextBox->Location = Point(81, 47);
this->partNumberTextBox->TabIndex = 2;
this->partPriceTextBox->Location = Point(81, 83);
this->partPriceTextBox->TabIndex = 3;
// Add the textbox controls to the form
this->Controls->Add(this->partNumberTextBox);
this->Controls->Add(this->partNameTextBox);
this->Controls->Add(this->partPriceTextBox);
// Handle the form's Load event.
this->Load += gcnew EventHandler(this,
&MainForm::OnMainFormLoad);
}
private:
void OnMainFormLoad(Object^ sender, EventArgs^ e)
{
// Set the DataSource of bindingSource to the Part type.
bindingSource->DataSource = Part::typeid;
// Bind the textboxes to the properties of the Part type,
// enabling formatting.
partNameTextBox->DataBindings->Add(
"Text", bindingSource, "PartName", true);
partNumberTextBox->DataBindings->Add(
"Text", bindingSource, "PartNumber", true);
//Bind the textbox to the PartPrice value
// with currency formatting.
partPriceTextBox->DataBindings->Add("Text", bindingSource, "PartPrice", true,
DataSourceUpdateMode::OnPropertyChanged, nullptr, "C");
// Handle the BindingComplete event for bindingSource and
// the partNameBinding.
bindingSource->BindingComplete +=
gcnew BindingCompleteEventHandler(this,
&MainForm::OnBindingSourceBindingComplete);
bindingSource->BindingComplete +=
gcnew BindingCompleteEventHandler(this,
&MainForm::OnPartNameBindingBindingComplete);
// Add a new part to bindingSource.
bindingSource->Add(gcnew Part("Widget", 1234, 12.45));
}
// Handle the BindingComplete event to catch errors and
// exceptions in binding process.
void OnBindingSourceBindingComplete(Object^ sender,
BindingCompleteEventArgs^ e)
{
if (e->BindingCompleteState ==
BindingCompleteState::Exception)
{
MessageBox::Show(String::Format(
CultureInfo::CurrentCulture,
"bindingSource: {0}", e->Exception->Message));
}
if (e->BindingCompleteState ==
BindingCompleteState::DataError)
{
MessageBox::Show(String::Format(
CultureInfo::CurrentCulture,
"bindingSource: {0}", e->Exception->Message));
}
}
// Handle the BindingComplete event to catch errors and
// exceptions in binding process.
void OnPartNameBindingBindingComplete(Object^ sender,
BindingCompleteEventArgs^ e)
{
if (e->BindingCompleteState ==
BindingCompleteState::Exception)
{
MessageBox::Show(String::Format(
CultureInfo::CurrentCulture,
"PartNameBinding: {0}", e->Exception->Message));
}
if (e->BindingCompleteState ==
BindingCompleteState::DataError)
{
MessageBox::Show(String::Format(
CultureInfo::CurrentCulture,
"PartNameBinding: {0}", e->Exception->Message));
}
}
};
using System;
using System.Drawing;
using System.Windows.Forms;
class Form1 : Form
{
private BindingSource BindingSource1 = new BindingSource();
private TextBox textBox1 = new TextBox();
private TextBox textBox2 = new TextBox();
private TextBox textBox3 = new TextBox();
public Form1()
{
//Set up the textbox controls.
this.textBox1.Location = new System.Drawing.Point(82, 13);
this.textBox1.TabIndex = 1;
this.textBox2.Location = new System.Drawing.Point(81, 47);
this.textBox2.TabIndex = 2;
this.textBox3.Location = new System.Drawing.Point(81, 83);
this.textBox3.TabIndex = 3;
// Add the textbox controls to the form
this.Controls.Add(this.textBox2);
this.Controls.Add(this.textBox1);
this.Controls.Add(this.textBox3);
// Handle the form's Load event.
this.Load += new System.EventHandler(this.Form1_Load);
}
Binding partNameBinding;
Binding partNumberBinding;
private void Form1_Load(object sender, EventArgs e)
{
// Set the DataSource of BindingSource1 to the Part type.
BindingSource1.DataSource = typeof(Part);
// Bind the textboxes to the properties of the Part type,
// enabling formatting.
partNameBinding = textBox1.DataBindings.Add("Text",
BindingSource1, "PartName", true);
partNumberBinding = textBox2.DataBindings.Add("Text", BindingSource1, "PartNumber",
true);
//Bind the textbox to the PartPrice value with currency formatting.
textBox3.DataBindings.Add("Text", BindingSource1, "PartPrice", true,
DataSourceUpdateMode.OnPropertyChanged, 0, "C");
// Handle the BindingComplete event for BindingSource1 and
// the partNameBinding.
partNumberBinding.BindingComplete +=
new BindingCompleteEventHandler(partNumberBinding_BindingComplete);
partNameBinding.BindingComplete +=
new BindingCompleteEventHandler(partNameBinding_BindingComplete);
// Add a new part to BindingSource1.
BindingSource1.Add(new Part("Widget", 1234, 12.45));
}
// Handle the BindingComplete event to catch errors and exceptions
// in binding process.
void partNumberBinding_BindingComplete(object sender,
BindingCompleteEventArgs e)
{
if (e.BindingCompleteState != BindingCompleteState.Success)
MessageBox.Show("partNumberBinding: " + e.ErrorText);
}
// Handle the BindingComplete event to catch errors and
// exceptions in binding process.
void partNameBinding_BindingComplete(object sender,
BindingCompleteEventArgs e)
{
if (e.BindingCompleteState != BindingCompleteState.Success)
MessageBox.Show("partNameBinding: " + e.ErrorText);
}
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.Run(new Form1());
}
}
// Represents a business object that throws exceptions when invalid values are
// entered for some of its properties.
public class Part
{
private string name;
private int number;
private double price;
public Part(string name, int number, double price)
{
PartName = name;
PartNumber = number;
PartPrice = price;
}
public string PartName
{
get { return name; }
set
{
if (value.Length <= 0)
throw new Exception("Each part must have a name.");
else
name = value;
}
}
public double PartPrice
{
get { return price; }
set { price = value; }
}
public int PartNumber
{
get { return number; }
set
{
if (value < 100)
throw new Exception("Invalid part number." +
" Part numbers must be greater than 100.");
else
number = value;
}
}
}
Imports System.Drawing
Imports System.Windows.Forms
Class Form1
Inherits Form
Private BindingSource1 As New BindingSource()
Private textBox1 As New TextBox()
Private textBox2 As New TextBox()
Private textBox3 As New TextBox()
Public Sub New()
'Set up the textbox controls.
Me.textBox1.Location = New System.Drawing.Point(82, 13)
Me.textBox1.TabIndex = 1
Me.textBox2.Location = New System.Drawing.Point(81, 47)
Me.textBox2.TabIndex = 2
Me.textBox3.Location = New System.Drawing.Point(81, 83)
Me.textBox3.TabIndex = 3
' Add the textbox controls to the form
Me.Controls.Add(Me.textBox2)
Me.Controls.Add(Me.textBox1)
Me.Controls.Add(Me.textBox3)
End Sub
Private WithEvents partNameBinding As Binding
Private WithEvents partNumberBinding As Binding
Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs) _
Handles Me.Load
' Set the DataSource of BindingSource1 to the Part type.
BindingSource1.DataSource = GetType(Part)
' Bind the textboxes to the properties of the Part type,
' enabling formatting.
partNameBinding = textBox1.DataBindings.Add("Text", BindingSource1, _
"PartName", True)
partNumberBinding = textBox2.DataBindings.Add("Text", BindingSource1, _
"PartNumber", True)
'Bind the textbox to the PartPrice value with currency formatting.
textBox3.DataBindings.Add("Text", BindingSource1, "PartPrice", _
True, DataSourceUpdateMode.OnPropertyChanged, 0, "C")
' Add a new part to BindingSource1.
BindingSource1.Add(New Part("Widget", 1234, 12.45))
End Sub
' Handle the BindingComplete event to catch errors and exceptions
' in binding process.
Sub partNumberBinding_BindingComplete(ByVal sender As Object, _
ByVal e As BindingCompleteEventArgs) _
Handles partNumberBinding.BindingComplete
If Not e.BindingCompleteState = BindingCompleteState.Success Then
MessageBox.Show("partNumberBinding: " + e.ErrorText)
End If
End Sub
' Handle the BindingComplete event to catch errors and exceptions
' in binding process.
Sub partNameBinding_BindingComplete(ByVal sender As Object, _
ByVal e As BindingCompleteEventArgs) _
Handles partNameBinding.BindingComplete
If Not e.BindingCompleteState = BindingCompleteState.Success Then
MessageBox.Show("partNameBinding: " + e.ErrorText)
End If
End Sub
<STAThread()> _
Shared Sub Main()
Application.EnableVisualStyles()
Application.Run(New Form1())
End Sub
End Class
' Represents a business object that throws exceptions when invalid
' values are entered for some of its properties.
Public Class Part
Private name As String
Private number As Integer
Private price As Double
Public Sub New(ByVal name As String, ByVal number As Integer, _
ByVal price As Double)
PartName = name
PartNumber = number
PartPrice = price
End Sub
Public Property PartName() As String
Get
Return name
End Get
Set(ByVal value As String)
If Value.Length <= 0 Then
Throw New Exception("Each part must have a name.")
Else
name = Value
End If
End Set
End Property
Public Property PartPrice() As Double
Get
Return price
End Get
Set(ByVal value As Double)
price = Value
End Set
End Property
Public Property PartNumber() As Integer
Get
Return number
End Get
Set(ByVal value As Integer)
If Value < 100 Then
Throw New Exception("Invalid part number." _
& " Part numbers must be greater than 100.")
Else
number = Value
End If
End Set
End Property
End Class
Lorsque le code est en cours d’exécution et qu’une chaîne vide est entrée pour le nom du composant ou qu’une valeur inférieure à 100 est entrée pour le numéro de partie, une zone de message s’affiche. Il s’agit d’un résultat de la gestion de l’événement Binding.BindingComplete pour ces liaisons de zone de texte.
Compilation du code
Cet exemple nécessite :
- Références aux assemblys System, System.Drawing et System.Windows.Forms.
Voir aussi
Collaborer avec nous sur GitHub
La source de ce contenu se trouve sur GitHub, où vous pouvez également créer et examiner les problèmes et les demandes de tirage. Pour plus d’informations, consultez notre guide du contributeur.
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