Header Ads

DataGridView in Windows Forms – Tips, Tricks and Frequently Asked Questions(FAQ)

DataGridView control is a Windows Forms control that gives you the ability to customize and edit tabular data. It gives you number of properties, methods and events to customize its appearance and behavior. In this article, we will discuss some frequently asked questions and their solutions. These questions have been collected from a variety of sources including some newsgroups, MSDN site and a few, answered by me at the MSDN forums.
Tip 1 – Populating a DataGridView
In this short snippet, we will populate a DataGridView using the LoadData() method. This method uses the SqlDataAdapter to populate a DataSet. The table ‘Orders’ in the DataSet is then bound to the BindingSource component which gives us the flexibility to choose/modify the data location.
C#

public partial class Form1 : Form
{
private SqlDataAdapter da;
private SqlConnection conn;
BindingSource bsource = new BindingSource();
DataSet ds = null;
string sql;
public Form1()
{
InitializeComponent();
}
private void btnLoad_Click(object sender, EventArgs e)
{
LoadData();
}
private void LoadData()
{
string connectionString = "Data Source=localhost;Initial Catalog=Northwind;" + "Integrated Security=SSPI;";
conn = new SqlConnection(connectionString);
sql = "SELECT OrderID, CustomerID, EmployeeID, OrderDate, Freight," + "ShipName, ShipCountry FROM Orders";
da = new SqlDataAdapter(sql, conn);
conn.Open();
ds = new DataSet();
SqlCommandBuilder commandBuilder = new SqlCommandBuilder(da);
da.Fill(ds, "Orders");
bsource.DataSource = ds.Tables["Orders"];
dgv.DataSource = bsource;
}
}

VB.NET

Public Partial Class Form1
Inherits Form
Private da As SqlDataAdapter
Private conn As SqlConnection
Private bsource As BindingSource = New BindingSource()
Private ds As DataSet = Nothing
Private sql As String
Public Sub New()
InitializeComponent()
End Sub
Private Sub btnLoad_Click(ByVal sender As Object, ByVal e As EventArgs)
LoadData()
End Sub
Private Sub LoadData()
Dim connectionString As String = "Data Source=localhost;Initial Catalog=Northwind;" & "Integrated Security=SSPI;"
conn = New SqlConnection(connectionString)
sql = "SELECT OrderID, CustomerID, EmployeeID, OrderDate, Freight," & "ShipName, ShipCountry FROM Orders"
da = New SqlDataAdapter(sql, conn)
conn.Open()
ds = New DataSet()
Dim commandBuilder As SqlCommandBuilder = New SqlCommandBuilder(da)
da.Fill(ds, "Orders")
bsource.DataSource = ds.Tables("Orders")
dgv.DataSource = bsource
End Sub
End Class

Tip 2 – Update the data in the DataGridView and save changes in the database
After editing the data in the cells, if you would like to update the changes permanently in the database, use the following code:
C#

private void btnUpdate_Click(object sender, EventArgs e)
{
DataTable dt = ds.Tables["Orders"];
this.dgv.BindingContext[dt].EndCurrentEdit();
this.da.Update(dt);
}

VB.NET

Private Sub btnUpdate_Click(ByVal sender As Object, ByVal e As EventArgs)
Dim dt As DataTable = ds.Tables("Orders")
Me.dgv.BindingContext(dt).EndCurrentEdit()
Me.da.Update(dt)
End Sub

Tip 3 – Display a confirmation box before deleting a row in the DataGridView
Handle the UserDeletingRow event to display a confirmation box to the user. If the user confirms the deletion, delete the row. If the user clicks cancel, set e.cancel = true which cancels the row deletion.
C#

private void dgv_UserDeletingRow(object sender, DataGridViewRowCancelEventArgs e)
{
if (!e.Row.IsNewRow)
{
DialogResult res = MessageBox.Show("Are you sure you want to delete this row?", "Delete confirmation",
MessageBoxButtons.YesNo, MessageBoxIcon.Question);
if (res == DialogResult.No)
e.Cancel = true;
}
}

VB.NET

Private Sub dgv_UserDeletingRow(ByVal sender As Object, ByVal e As DataGridViewRowCancelEventArgs)
If (Not e.Row.IsNewRow) Then
Dim res As DialogResult = MessageBox.Show("Are you sure you want to delete this row?", "Delete confirmation", MessageBoxButtons.YesNo, MessageBoxIcon.Question)
If res = DialogResult.No Then
e.Cancel = True
End If
End If
End Sub

Tip 4 – How to autoresize column width in the DataGridView
The snippet shown below, first auto-resizes the columns to fit its content. Then the AutoSizeColumnsMode is set to the ‘DataGridViewAutoSizeColumnsMode.AllCells’ enumeration value which automatically adjust the widths of the columns when the data changes.
C#

private void btnResize_Click(object sender, EventArgs e)
{
dgv.AutoResizeColumns();
dgv.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.AllCells;
}

VB.NET

Private Sub btnResize_Click(ByVal sender As Object, ByVal e As EventArgs)
dgv.AutoResizeColumns()
dgv.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.AllCells
End Sub


Tip 5 - Select and Highlight an entire row in DataGridView
C#

int rowToBeSelected = 3; // third row
if (dgv.Rows.Count >= rowToBeSelected)
{
// Since index is zero based, you have to subtract 1
dgv.Rows[rowToBeSelected - 1].Selected = true;
}

VB.NET
 
Dim rowToBeSelected As Integer = 3 ' third row
If dgv.Rows.Count >= rowToBeSelected Then
' Since index is zero based, you have to subtract 1
dgv.Rows(rowToBeSelected - 1).Selected = True
End If

Tip 6 - How to scroll programmatically to a row in the DataGridView
The DataGridView has a property called FirstDisplayedScrollingRowIndex that can be used in order to scroll to a row programmatically.
C#

int jumpToRow = 20;
if (dgv.Rows.Count >= jumpToRow && jumpToRow >= 1)
{
dgv.FirstDisplayedScrollingRowIndex = jumpToRow;
dgv.Rows[jumpToRow].Selected = true;
}

VB.NET

Dim jumpToRow As Integer = 20
If dgv.Rows.Count >= jumpToRow AndAlso jumpToRow >= 1 Then
dgv.FirstDisplayedScrollingRowIndex = jumpToRow
dgv.Rows(jumpToRow).Selected = True
End If

Tip 7 - Calculate a column total in the DataGridView and display in a textbox
A common requirement is to calculate the total of a currency field and display it in a textbox. In the snippet below, we will be calculating the total of the ‘Freight’ field. We will then display the data in a textbox by formatting the result (observe the ToString("c")) while displaying the data, which displays the culture-specific currency.
C#

private void btnTotal_Click(object sender, EventArgs e)
{
if(dgv.Rows.Count > 0)
txtTotal.Text = Total().ToString("c");
}
private double Total()
{
double tot = 0;
int i = 0;
for (i = 0; i <>
{
tot = tot + Convert.ToDouble(dgv.Rows[i].Cells["Freight"].Value);
}
return tot;
}

VB.NET

Private Sub btnTotal_Click(ByVal sender As Object, ByVal e As EventArgs)
If dgv.Rows.Count > 0 Then
txtTotal.Text = Total().ToString("c")
End If
End Sub
Private Function Total() As Double
Dim tot As Double = 0
Dim i As Integer = 0
For i = 0 To dgv.Rows.Count - 1
tot = tot + Convert.ToDouble(dgv.Rows(i).Cells("Freight").Value)
Next i
Return tot
End Function

Tip 8 - Change the Header Names in the DataGridView
If the columns being retrieved from the database do not have meaningful names, we always have the option of changing the header names as shown in this snippet:
C#

private void btnChange_Click(object sender, EventArgs e)
{
dgv.Columns[0].HeaderText = "MyHeader1";
dgv.Columns[1].HeaderText = "MyHeader2";
}

VB.NET

Private Sub btnChange_Click(ByVal sender As Object, ByVal e As EventArgs)
dgv.Columns(0).HeaderText = "MyHeader1"
dgv.Columns(1).HeaderText = "MyHeader2"
End Sub

Tip 9 - Change the Color of Cells, Rows and Border in the DataGridView
C#

private void btnCellRow_Click(object sender, EventArgs e)
{
// Change ForeColor of each Cell
this.dgv.DefaultCellStyle.ForeColor = Color.Coral;
// Change back color of each row
this.dgv.RowsDefaultCellStyle.BackColor = Color.AliceBlue;
// Change GridLine Color
this.dgv.GridColor = Color.Blue;
// Change Grid Border Style
this.dgv.BorderStyle = BorderStyle.Fixed3D;
}

VB.NET

Private Sub btnCellRow_Click(ByVal sender As Object, ByVal e As EventArgs)
' Change ForeColor of each Cell
Me.dgv.DefaultCellStyle.ForeColor = Color.Coral
' Change back color of each row
Me.dgv.RowsDefaultCellStyle.BackColor = Color.AliceBlue
' Change GridLine Color
Me.dgv.GridColor = Color.Blue
' Change Grid Border Style
Me.dgv.BorderStyle = BorderStyle.Fixed3D
End Sub

Tip 10 - Hide a Column in the DataGridView
If you would like to hide a column based on a certain condition, here’s a snippet for that.
C#

private void btnHide_Click(object sender, EventArgs e)
{
this.dgv.Columns["EmployeeID"].Visible = false;
}

VB.NET

Private Sub btnHide_Click(ByVal sender As Object, ByVal e As EventArgs)
Me.dgv.Columns("EmployeeID").Visible = False
End Sub


Tip 11 - Handle SelectedIndexChanged of a ComboBox in the DataGridView
To handle the SelectedIndexChanged event of a DataGridViewComboBox, you need to use the DataGridView.EditingControlShowing event as shown below. You can then retrieve the selected index or the selected text of the combobox.
C#

private void dataGridView1_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
{
ComboBox editingComboBox = (ComboBox)e.Control;
if(editingComboBox != null)
editingComboBox.SelectedIndexChanged += new System.EventHandler(this.editingComboBox_SelectedIndexChanged);
}
private void editingComboBox_SelectedIndexChanged(object sender, System.EventArgs e)
{
ComboBox comboBox1 = (ComboBox)sender;
// Display index
MessageBox.Show(comboBox1.SelectedIndex.ToString());
// Display value
MessageBox.Show(comboBox1.Text);
}

VB.NET

Private Sub dataGridView1_EditingControlShowing(ByVal sender As Object, ByVal e As DataGridViewEditingControlShowingEventArgs)
Dim editingComboBox As ComboBox = CType(e.Control, ComboBox)
If Not editingComboBox Is Nothing Then
AddHandler editingComboBox.SelectedIndexChanged, AddressOf editingComboBox_SelectedIndexChanged
End If
End Sub
Private Sub editingComboBox_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs)
Dim comboBox1 As ComboBox = CType(sender, ComboBox)
' Display index
MessageBox.Show(comboBox1.SelectedIndex.ToString())
' Display value
MessageBox.Show(comboBox1.Text)
End Sub

Tip 12 - Change Color of Alternate Rows in the DataGridView
C#

private void btnAlternate_Click(object sender, EventArgs e)
{
this.dgv.RowsDefaultCellStyle.BackColor = Color.White;
this.dgv.AlternatingRowsDefaultCellStyle.BackColor = Color.Aquamarine;
}

VB.NET

Private Sub btnAlternate_Click(ByVal sender As Object, ByVal e As EventArgs)
Me.dgv.RowsDefaultCellStyle.BackColor = Color.White
Me.dgv.AlternatingRowsDefaultCellStyle.BackColor = Color.Aquamarine
End Sub

Tip 13 - Formatting Data in the DataGridView
The DataGridView exposes properties that enable you to format data such as displaying a currency column in the culture specific currency or displaying nulls in a desired format and so on.
C#

private void btnFormat_Click(object sender, EventArgs e)
{
// display currency in culture-specific currency for
this.dgv.Columns["Freight"].DefaultCellStyle.Format = "c";
// display nulls as 'NA'
this.dgv.DefaultCellStyle.NullValue = "NA";
}

VB.NET

Private Sub btnFormat_Click(ByVal sender As Object, ByVal e As EventArgs)
' display currency in culture-specific currency for
Me.dgv.Columns("Freight").DefaultCellStyle.Format = "c"
' display nulls as 'NA'
Me.dgv.DefaultCellStyle.NullValue = "NA"
End Sub

Tip 14 – Change the order of columns in the DataGridView
In order to change the order of columns, just set the DisplayIndex property of the DataGridView to the desired value. Remember that the index is zero based.
C#

private void btnReorder_Click(object sender, EventArgs e)
{
dgv.Columns["CustomerID"].DisplayIndex = 5;
dgv.Columns["OrderID"].DisplayIndex = 3;
dgv.Columns["EmployeeID"].DisplayIndex = 1;
dgv.Columns["OrderDate"].DisplayIndex = 2;
dgv.Columns["Freight"].DisplayIndex = 6;
dgv.Columns["ShipCountry"].DisplayIndex = 0;
dgv.Columns["ShipName"].DisplayIndex = 4;
}

VB.NET

Private Sub btnReorder_Click(ByVal sender As Object, ByVal e As EventArgs)
dgv.Columns("CustomerID").DisplayIndex = 5
dgv.Columns("OrderID").DisplayIndex = 3
dgv.Columns("EmployeeID").DisplayIndex = 1
dgv.Columns("OrderDate").DisplayIndex = 2
dgv.Columns("Freight").DisplayIndex = 6
dgv.Columns("ShipCountry").DisplayIndex = 0
dgv.Columns("ShipName").DisplayIndex = 4
End Sub

I hope this article was useful and I thank you for viewing it.

1 comment:

  1. how to delete data from the data grid view affecting the database too programatically?

    ReplyDelete


Powered by Blogger.