Avoid SelectedIndexChanged function of all the comboboxes in a groupBox from getting fired while changing selection only for one of them.

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I am filling 8 combobox by using their DataSource property with same data from dataset and have defined SelectedIndexChanged function for all of them.

Now my problem is that SelectedIndexChanged function of all the comboboxes get fired if I change my selection for any of the comboboxes.

XML

foreach (var comboBox in panel2.Controls.OfType<ComboBox>())
{
    comboBox.DataSource = ds.Tables[1];
    comboBox.DisplayMember = "FeeName";
    comboBox.ValueMember = "ID";
}

Posted 21-Mar-14 9:19am

devishankarmishra

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ZurdoDev 21-Mar-14 15:45pm

That means you wired them all up to the same event.

3 solutions

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BillWoodruff · Answer 1 · 2014-03-21T10:05:00

Solution 1

Try this:

C#

foreach (var comboBox in panel2.Controls.OfType<ComboBox>())
{
    comboBox.DataSource = ds.Tables[1].Copy();
    comboBox.DisplayMember = "FeeName";
    comboBox.ValueMember = "ID";
}

Posted 21-Mar-14 10:05am

BillWoodruff

Comments

Sergey Alexandrovich Kryukov 21-Mar-14 18:18pm

My 5, but I added a different variant of the loop and explained why it's a bit better, in certain aspect — Solution 2.
—SA

Sergey Alexandrovich Kryukov · Answer 2 · 2014-03-21T12:16:00

In addition to Solution 1:

The use of the OfType<> method looks of course very elegant, is clear, readable and reliable, but it is not the best in terms of performance and memory usage, because it creates an intermediate collection object which is not really needed for this code. Therefore, a bit longer code is more practical:

C#

foreach(Control control in panel2.Controls) {
    ComboBox comboBox = control as ComboBox;
    if (comboBox == null) continue;
    comboBox.//... dereference if and do the same thing
    //...
}

—SA

Marcin Kozub · Answer 3 · 2014-03-21T12:21:00

Maybe solution is to add some kind of flag to the form? Make private field like:

C#

private bool isUpdating = false;

In your code responsible for updating comboboxes do some kind of trick:

C#

private void UpdateDataSources()
{
    isUpdating = true;

    foreach (var comboBox in panel2.Controls.OfType<ComboBox>())
    {
        comboBox.DataSource = ds.Tables[1];
        comboBox.DisplayMember = "FeeName";
        comboBox.ValueMember = "ID";
    }

    isUpdating = false;
}

And then in SelectedIndexChanged of every combobox (or if shared event handler) insert IF statement:

C#

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
    if (!isUpdating)
    {
        // Real code goes here
    }
}

Consider setting SelectedIndexItem to -1 after updating ComboBoxes datasources.

I didn't tried this but i think that can help you. Let me know :)