Custom Event always Showing null While invoking

Question

4.00/5 (1 vote)

See more:

Hi,

I wrote a custom event in C sharp(Silverlight).Here is the code.

C#

public delegate void MyEvent(object sender, TreeGridEventArgs e);
        public event MyEvent SLTreeGridSelectionChanged;
        void RaiseSLTreeGridSelectionChanged(TreeGridEventArgs e)
        {
            if (SLTreeGridSelectionChanged != null)
            {
                SLTreeGridSelectionChanged(this, e);
            }
        }

and here I will invoke it( during the SelectionChanged event of DataGrid)
..

C#

private void SLDataGrid_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
         
            if (CurrentSELedNode != null)
            {
                TreeGridRow row = (TreeGridRow)CurrentSELedNode.Tag;
                RaiseSLTreeGridSelectionChanged(new TreeGridEventArgs(row));
            }

        }

but while raising the event "SLTreeGridSelectionChanged" always shows null. Why this is happening? Any idea..? Please help me..

Posted 22-Mar-11 21:10pm

Arun India

Add a Solution

Comments

Ankit Rajput 23-Mar-11 3:14am

Have you handled it in your code?

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Kubajzz · Accepted Answer · 2011-03-22T21:13:00

Solution 1

The event is null as long as there are no subscribers. If you create an event handler and use the += syntax to subscribe for the event, it won't be null any more.

Posted 22-Mar-11 21:13pm

Kubajzz

Comments

Arun India 23-Mar-11 4:23am

But Kubajzz.. this code is working fine for me.. What I am missing..?

public delegate void EventHandler(object sender, TreeGridEventArgs e);
public event EventHandler TreeGridRatingChanged;
void RaiseSLTreeGridRatingChanged(TreeGridEventArgs e)
{
if (TreeGridRatingChanged != null)
{
TreeGridRatingChanged(this, e);
}
}

I am Raising it Here..

private void RatingItem_Click(object sender, RoutedEventArgs e)
{
RaiseSLTreeGridRatingChanged(new TreeGridEventArgs(treeGridRow));
}

Arun India 23-Mar-11 4:33am

Hi Kubajzz..
Now It is working fine. Your answer is absolutely correct. After defining it, I missed to use it in the code where I include the dll.
Thank you Kubajzz for your reply..

Sergey Alexandrovich Kryukov 23-Mar-11 16:43pm

Correct, a 5.
--SA