This is a REAL Clean way to display error messages for a form.

The following example demonstrates using the ErrorProvider class to notify the user of a data entry error.

[C#]
using System;
using System.Drawing;
using System.Windows.Forms;

namespace ErrorProvider
{
public class Form1 : System.Windows.Forms.Form
{
private System.Windows.Forms.Label label1;
private System.Windows.Forms.Label label2;
private System.Windows.Forms.Label label4;
private System.Windows.Forms.Label label5;
private System.Windows.Forms.Label label6;
private System.Windows.Forms.Label label3;
private System.Windows.Forms.TextBox nameTextBox1;
private System.Windows.Forms.NumericUpDown ageUpDownPicker;
private System.Windows.Forms.ComboBox favoriteColorComboBox;
private System.Windows.Forms.ErrorProvider ageErrorProvider;
private System.Windows.Forms.ErrorProvider nameErrorProvider;
private System.Windows.Forms.ErrorProvider favoriteColorErrorProvider;

[STAThread]
static void Main()
{
Application.Run(new Form1());
}

public Form1()
{
this.nameTextBox1 = new System.Windows.Forms.TextBox();
this.label1 = new System.Windows.Forms.Label();
this.label2 = new System.Windows.Forms.Label();
this.ageUpDownPicker = new System.Windows.Forms.NumericUpDown();
this.favoriteColorComboBox = new System.Windows.Forms.ComboBox();
this.label3 = new System.Windows.Forms.Label();
this.label4 = new System.Windows.Forms.Label();
this.label5 = new System.Windows.Forms.Label();
this.label6 = new System.Windows.Forms.Label();

// Name Label
this.label1.Location = new System.Drawing.Point(56, 32);
this.label1.Size = new System.Drawing.Size(40, 23);
this.label1.Text = “Name:”;

// Age Label
this.label2.Location = new System.Drawing.Point(40, 64);
this.label2.Size = new System.Drawing.Size(56, 23);
this.label2.Text = “Age (3-5)”;

// Favorite Color Label
this.label3.Location = new System.Drawing.Point(24, 96);
this.label3.Size = new System.Drawing.Size(80, 24);
this.label3.Text = “Favorite color”;

// ErrorBlinkStyle.AlwaysBlink Label
this.label4.Location = new System.Drawing.Point(264, 32);
this.label4.Size = new System.Drawing.Size(160, 23);
this.label4.Text = “ErrorBlinkStyle.AlwaysBlink”;

// ErrorBlinkStyle.BlinkIfDifferentError Label
this.label5.Location = new System.Drawing.Point(264, 64);
this.label5.Size = new System.Drawing.Size(200, 23);
this.label5.Text = “ErrorBlinkStyle.BlinkIfDifferentError”;

// ErrorBlinkStyle.NeverBlink Label
this.label6.Location = new System.Drawing.Point(264, 96);
this.label6.Size = new System.Drawing.Size(200, 23);
this.label6.Text = “ErrorBlinkStyle.NeverBlink”;

// Name TextBox
this.nameTextBox1.Location = new System.Drawing.Point(112, 32);
this.nameTextBox1.Size = new System.Drawing.Size(120, 20);
this.nameTextBox1.TabIndex = 0;
this.nameTextBox1.Validated += new System.EventHandler(this.nameTextBox1_Validated);

// Age NumericUpDown
this.ageUpDownPicker.Location = new System.Drawing.Point(112, 64);
this.ageUpDownPicker.Maximum = new System.Decimal(new int[] {150,0,0,0});
this.ageUpDownPicker.TabIndex = 4;
this.ageUpDownPicker.Validated += new System.EventHandler(this.ageUpDownPicker_Validated);

// Favorite Color ComboBox
this.favoriteColorComboBox.Items.AddRange(new object[] {”None”,”Red”,”Yellow”,
“Green”,”Blue”,”Purple”});
this.favoriteColorComboBox.Location = new System.Drawing.Point(112, 96);
this.favoriteColorComboBox.Size = new System.Drawing.Size(120, 21);
this.favoriteColorComboBox.TabIndex = 5;
this.favoriteColorComboBox.Validated += new System.EventHandler(this.favoriteColorComboBox_Validated);

// Set up how the form should be displayed and add the controls to the form.
this.ClientSize = new System.Drawing.Size(464, 150);
this.Controls.AddRange(new System.Windows.Forms.Control[] {
this.label6,this.label5,this.label4,this.label3,
this.favoriteColorComboBox,this.ageUpDownPicker,
this.label2,this.label1,this.nameTextBox1});
this.Text = “Error Provider Example”;

// Create and set the ErrorProvider for each data entry control.

nameErrorProvider = new  System.Windows.Forms.ErrorProvider();
nameErrorProvider.SetIconAlignment (this.nameTextBox1, ErrorIconAlignment.MiddleRight);
nameErrorProvider.SetIconPadding (this.nameTextBox1, 2);
nameErrorProvider.BlinkRate = 1000;
nameErrorProvider.BlinkStyle = System.Windows.Forms.ErrorBlinkStyle.AlwaysBlink;

ageErrorProvider = new  System.Windows.Forms.ErrorProvider();
ageErrorProvider.SetIconAlignment (this.ageUpDownPicker, ErrorIconAlignment.MiddleRight);
ageErrorProvider.SetIconPadding (this.ageUpDownPicker, 2);
ageErrorProvider.BlinkStyle = System.Windows.Forms.ErrorBlinkStyle.BlinkIfDifferentError;

favoriteColorErrorProvider = new  System.Windows.Forms.ErrorProvider();
favoriteColorErrorProvider.SetIconAlignment (this.ageUpDownPicker, ErrorIconAlignment.MiddleRight);
favoriteColorErrorProvider.SetIconPadding (this.ageUpDownPicker, 2);
favoriteColorErrorProvider.BlinkRate = 1000;
favoriteColorErrorProvider.BlinkStyle = System.Windows.Forms.ErrorBlinkStyle.NeverBlink;
}

private void nameTextBox1_Validated(object sender, System.EventArgs e)
{
if(IsNameValid())
{
// Clear the error, if any, in the error provider.
nameErrorProvider.SetError(this.nameTextBox1, “”);
}
else
{
// Set the error if the name is not valid.
nameErrorProvider.SetError(this.nameTextBox1, “Name is required.”);
}
}

private void ageUpDownPicker_Validated(object sender, System.EventArgs e)
{
if (IsAgeTooYoung())
{
// Set the error if the age is too young.
ageErrorProvider.SetError(this.ageUpDownPicker, “Age not old enough”);
}
else if (IsAgeTooOld())
{
// Set the error if the age is too old.
ageErrorProvider.SetError(this.ageUpDownPicker, “Age is too old”);
}
else
{
// Clear the error, if any, in the error provider.
ageErrorProvider.SetError(this.ageUpDownPicker, “”);
}
}

private void favoriteColorComboBox_Validated(object sender, System.EventArgs e)
{
if (!IsColorValid())
{
// Set the error if the favorite color is not valid.
favoriteColorErrorProvider.SetError(this.favoriteColorComboBox, “Must select a color.”);
}
else
{
// Clear the error, if any, in the error provider.
favoriteColorErrorProvider.SetError(this.favoriteColorComboBox, “”);
}
}

// Functions to verify data.
private bool IsNameValid()
{
// Determine whether the text box contains a zero-length string.
return (nameTextBox1.Text.Length > 0);
}

private bool IsAgeTooYoung()
{
// Determine whether the age value is less than three.
return (ageUpDownPicker.Value < 3);
}

private bool IsAgeTooOld()
{
// Determine whether the age value is greater than five.
return (ageUpDownPicker.Value > 5 );
}

private bool IsColorValid()
{
// Determine whether the favorite color has a valid value.
return ((favoriteColorComboBox.SelectedItem != null) &&
(!favoriteColorComboBox.SelectedItem.ToString().Equals(”None”)));
}
}
}

[ reference  ]

This entry was posted on Tuesday, December 19th, 2006 at 2:43 pm and is filed under Web_Appz. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.