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DataGridView.NewRowNeeded Event

Note: This event is new in the .NET Framework version 2.0.

Occurs when the VirtualMode property of the DataGridView is true and the user navigates to the new row at the bottom of the DataGridView.

Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in system.windows.forms.dll)

public event DataGridViewRowEventHandler NewRowNeeded
/** @event */
public void add_NewRowNeeded (DataGridViewRowEventHandler value)

/** @event */
public void remove_NewRowNeeded (DataGridViewRowEventHandler value)

JScript supports the use of events, but not the declaration of new ones.

When the DataGridView is in virtual mode, this event allows a new entry to be created in the data store for the new row, and it also allows for the row to be populated with default values.

For more information about handling events, see Consuming Events.

The following code example uses the NewRowNeeded event to track when a new row is being added, so logic in the CellValueNeeded event handler can initialize a new row's cell to an initial value. This example is part of a larger example available in the VirtualMode reference topic.

bool newRowNeeded;
private void dataGridView1_NewRowNeeded(object sender,
    DataGridViewRowEventArgs e)
{
    newRowNeeded = true;
}

const int initialSize = 5000000;
int numberOfRows = initialSize;

private void dataGridView1_RowsAdded(object sender,
     DataGridViewRowsAddedEventArgs e)
{
    if (newRowNeeded)
    {
        newRowNeeded = false;
        numberOfRows = numberOfRows + 1;
    }
}

#region "data store maintance"
const int initialValue = -1;

private void dataGridView1_CellValueNeeded(object sender,
    DataGridViewCellValueEventArgs e)
{
    if (store.ContainsKey(e.RowIndex))
    {
        // Use the store if the e value has been modified 
        // and stored.            
        e.Value = store[e.RowIndex];
    }
    else if (newRowNeeded && e.RowIndex == numberOfRows)
    {
        if (dataGridView1.IsCurrentCellInEditMode)
        {
            e.Value = initialValue;
        }
        else
        {
            // Show a blank value if the cursor is just resting
            // on the last row.
            e.Value = String.Empty;
        }
    }
    else
    {
        e.Value = e.RowIndex;
    }
}

private void dataGridView1_CellValuePushed(object sender,
    DataGridViewCellValueEventArgs e)
{
    store.Add(e.RowIndex, int.Parse(e.Value.ToString()));
}
#endregion

private Dictionary<int, int> store = new Dictionary<int, int>();

private boolean newRowNeeded;

private void dataGridView1_NewRowNeeded(Object sender,
    DataGridViewRowEventArgs e)
{
    newRowNeeded = true;
} //dataGridView1_NewRowNeeded

private final int INITIALSIZE = 5000000;
private int numberOfRows = INITIALSIZE;

private void dataGridView1_RowsAdded(Object sender,
    DataGridViewRowsAddedEventArgs e)
{
    if (newRowNeeded) {
        newRowNeeded = false;
        numberOfRows = numberOfRows + 1;
    }
} //dataGridView1_RowsAdded

#region "data store maintance"
private final int INITIALVALUE = -1;

private void dataGridView1_CellValueNeeded(Object sender,
    DataGridViewCellValueEventArgs e)
{
    if (store.ContainsKey(e.get_RowIndex())) {
        // Use the store if the e value has been modified 
        // and stored.            
        e.set_Value((Int32)store.get_Item(e.get_RowIndex()));
    }
    else {
        if (newRowNeeded && e.get_RowIndex() == numberOfRows) {
            if (dataGridView1.get_IsCurrentCellInEditMode()) {
                e.set_Value((Int32)INITIALVALUE);
            }
            else {
                // Show a blank e if the cursor is just loitering
                // over(the)
                // last row.
                e.set_Value("");
            }
        }
        else {
            e.set_Value((Int32)e.get_RowIndex());
        }
    }
} //dataGridView1_CellValueNeeded

private void dataGridView1_CellValuePushed(Object sender,
    DataGridViewCellValueEventArgs e)
{
    store.Add(e.get_RowIndex(), Int32.Parse(e.get_Value().ToString()));
} //dataGridView1_CellValuePushed
#endregion

private Dictionary<int, int> store = new Dictionary<int, int>();

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0

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