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c#winformsdata-bindingdatagridviewselectionchanged
Sanjeev4evr
Sanjeev4evr

Reputation: 413

DataGridView selectionChanged event firing multiple times

In my application I am using DataGridView to display the list. When user select a record in the datagridview, it should display details in the other panel. For selection I was asked to use DataGridView1_SelectionChanged event.

The DataGridView should contain only one column, but the details display may have more information of the selected record( We can get the all the details form the database by querying with the selected Primary key value).

Please tell Is it possible to get datakey(Primary key) of the selected DataGridView record. Does DataGridView will bind based on Primary key ?

Edit

I have implemented DataGridView1.Columns["ID"].Visible = false. It worked well. For selection I added DataGridView1_SelectionChanged event.

But DataGridView1_SelectionChanged event is firing multiple times.

Upvotes: 13

Views: 17083

Answers (4)

AdamRossWalker
AdamRossWalker

Reputation: 314

If the data binding is reset, you can get one SelectionChanged notifying that the list is temporarily empty followed by another after the data has populated. Worse, the selected item may not even have changed since before the reset. I verified this by checking SelectedCells on each call.

One solution is to use an invalidation variable, and check in the Application.Idle event. This has the nice effect of grouping changes and avoiding unnecessary updates. Application.Idle runs as soon as the message pump is empty, so the user won't notice a delay. It's even better if you check if a change is even required after the grid has sorted itself out.

You'll need to set up the static form instance property in the constructor.

private bool isViewUpToDate = false;

private void DataGrid_SelectionChanged(object sender, EventArgs e) => isViewUpToDate = false;

public void CheckDataGridSelectionView()
{
    if (isViewUpToDate)
        return;

    // Logic goes here

    isViewUpToDate = true;
}

static void Main()
{
    Application.Idle += (sender, eventData) => MainForm.Instance?.CheckDataGridSelectionView();

    // ...
}

Upvotes: 2

Mustafa Yasser
Mustafa Yasser

Reputation: 411

You can use DataGrid.focused property in selectionchanged event before executing the code like this :

private void dg_SelectionChanged(object sender, EventArgs e)
    {
        if (dg.Focused)
        {
            // your code
        }
    }

Upvotes: 41

Hưng
Hưng

Reputation: 21

I got the same problems today, after hours of experiment with it, I found a solution or rather a workaround for this problem

this.dgvSearchResult.SelectionChanged -= dgvSearchResult_SelectionChanged;
this.onSearch();
this.dgvSearchResult.SelectionChanged += new EventHandler(dgvSearchResult_SelectionChanged);

Hope it's help

Upvotes: 2

Shell
Shell

Reputation: 6849

I have tried with RowEnter event but, it works fine for me. How do you check it? using message box or placing break point in the event. Because, breakpoint and messagebox will loos the focus from the selected row. Then, when you continue after messagebox or breakpoint the grid will get focused back and the event will be executed again.

Try following step to check event execution. enter image description here

To handle multiple execution.

int LastRowIndex =-1;

private void dgv_RowEnter(...)
{
    if (LastRowIndex != e.RowIndex)
    {
        //Place your code here.
    }
    LastRowIndex = e.RowIndex;
}

Upvotes: 1

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