How do I make an Event in the Usercontrol and have it handled in the Main Form

Question

I have a custom usercontrol and I want to do something relatively simple   When ever a numeric up down in that usercontrol s value changes  have the main form update a display window   This is not a problem if the NUD was not in a usercontrol but I can t seem to figure out how to have the event handled by the mainform and not the usercontrol

User · Accepted Answer

You need to create an event handler for the user control that is raised when an event from within the user control is fired. This will allow you to bubble the event up the chain so you can handle the event from the form.

When clicking Button1 on the UserControl, i'll fire Button1_Click which triggers UserControl_ButtonClick on the form:

User control:

[Browsable(true)] [Category("Action")] 
[Description("Invoked when user clicks button")]
public event EventHandler ButtonClick;

protected void Button1_Click(object sender, EventArgs e)
{
    //bubble the event up to the parent
    if (this.ButtonClick!= null)
        this.ButtonClick(this, e);               
}

Form:

UserControl1.ButtonClick += new EventHandler(UserControl_ButtonClick);

protected void UserControl_ButtonClick(object sender, EventArgs e)
{
    //handle the event 
}

Notes:

Newer Visual Studio versions suggest that instead of if (this.ButtonClick!= null) this.ButtonClick(this, e); you can use ButtonClick?.Invoke(this, e);, which does essentially the same, but is shorter.
The Browsable attribute makes the event visible in Visual Studio's designer (events view), Category shows it in the "Action" category, and Description provides a description for it. You can omit these attributes completely, but making it available to the designer it is much more comfortable, since VS handles it for you.

User · Answer

one of the easy way to do that is use landa function without any problem like  userControl Material1 simpleButton4 Click     s  ee    gt                                Save mat mat global

User · Answer

Try mapping it   Try placing this code in your UserControl   public event EventHandler ValueChanged     add   numericUpDown1 ValueChanged    value      remove   numericUpDown1 ValueChanged -  value        then your UserControl will have the ValueChanged event you normally see with the NumericUpDown control

User · Answer

you can do like this     the below example shows text box user control  value changed         Declare a delegate  public delegate void ValueChangedEventHandler object sender  ValueChangedEventArgs e   public partial class SampleUserControl   TextBox            public SampleUserControl                   InitializeComponent                   Declare an event      public event ValueChangedEventHandler ValueChanged       protected virtual void OnValueChanged ValueChangedEventArgs e                  if  ValueChanged    null               ValueChanged this e                  private void SampleUserControl TextChanged object sender  EventArgs e                  TextBox tb     TextBox sender           int value           if   int TryParse tb Text  out value                value   0              Raise the event         OnValueChanged  new ValueChangedEventArgs value

User · Answer

For those looking to do this in VB  here s how I got mine to work with a checkbox   Background  I was trying to make my own checkbox that is a slider switch control  I ve only included the relevant code for this question   In User control MyCheckbox ascx   lt asp CheckBox ID  checkbox  runat  server  AutoPostBack  true    gt    In User control MyCheckbox ascx vb  Create an EventHandler  OnCheckChanged    When an event fires on the control     ID  checkbox   inside your    usercontrol  MyCheckBox ascx   then fire your EventHandler  OnCheckChanged    Public Event OnCheckChanged As EventHandler  Private Sub checkbox CheckedChanged sender As Object  e As EventArgs  Handles checkbox CheckedChanged     RaiseEvent OnCheckChanged Me  e  End Sub   In Page MyPage aspx   lt uc MyCheckbox runat  server  ID  myCheck  OnCheckChanged  myCheck CheckChanged    gt    Note  myCheck CheckChanged didn t fire until I added the Handles clause below  In Page MyPage aspx vb  Protected Sub myCheck CheckChanged  sender As Object  e As EventArgs  Handles scTransparentVoting OnCheckChanged      Do some page logic here End Sub

[c#] How do I make an Event in the Usercontrol and have it handled in the Main Form?

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