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

长平狐 发布于 2013/01/06 11:23
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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 ObjectByVal 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 ObjectByVal 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 ObjectByVal 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 ObjectByVal 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 < dgv.Rows.Count; i++)
            {
                tot = tot + Convert.ToDouble(dgv.Rows[i].Cells["Freight"].Value);
            }
            return tot;
        }
VB.NET
Private Sub btnTotal_Click(ByVal sender As ObjectByVal 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 ObjectByVal 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 ObjectByVal 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 ObjectByVal 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 ObjectByVal 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 ObjectByVal 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 ObjectByVal 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 ObjectByVal 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 ObjectByVal 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.


原文链接:http://blog.csdn.net/sunboy_2050/article/details/5375515
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