Drag and Drop from Datagridview in C#

Expert Comment

by:gbarcalow

ID: 217523792008-06-10

I had a problem with dragging from the DataGridView and finally I had to settle on it being a right-click drag and drop. All you have to do is invoke the DoDragDrop method on the DataGridView. Then look for the right object type being passed into the treeview.

See the code for a small example...

private void dataGrid_MouseDown(object sender, MouseEventArgs e)
{
    int[] rowIDs = new int[dataGrid.SelectedRows.Count];
    for (int i = 0; i != dataGrid.SelectedRows.Count; i++)
    {
        rowIDs[i] = dataGrid.SelectedRows.Cells[0];
    }
    dataGrid.DoDragDrop(rowIDs, DragDropEffected.Link);
}

Expert Comment

by:gbarcalow

ID: 217523882008-06-10

I am sorry, I forgot to include to code the check if it's the right mouse button.

private void dataGrid_MouseDown(object sender, MouseEventArgs e)
{
    if (e.Button == MouseButtons.Right)
    {
        int[] rowIDs = new int[dataGrid.SelectedRows.Count];
        for (int i = 0; i != dataGrid.SelectedRows.Count; i++)
        {
            rowIDs[i] = dataGrid.SelectedRows.Cells[0];
        }
        dataGrid.DoDragDrop(rowIDs, DragDropEffected.Link);
    }
}

Author Comment

by:tomcahill

ID: 217527512008-06-10

I receive the following errors:

Error 1 'System.Windows.Forms.DataGridViewSelectedRowCollection' does not contain a definition for 'Cells' and no extension method 'Cells' accepting a first argument of type 'System.Windows.Forms.DataGridViewSelectedRowCollection' could be found (are you missing a using directive or an assembly reference?) C:\Users\tom\Documents\Visual Studio 2008\Projects\IOPS\IOPS\Form1.cs 680 60 IOPS
Error 2 The name 'DragDropEffected' does not exist in the current context C:\Users\tom\Documents\Visual Studio 2008\Projects\IOPS\IOPS\Form1.cs 682 50 IOPS

Expert Comment

by:gbarcalow

ID: 217529282008-06-10

Sorry about my types, I didnt have access to VS at the time.

Error 1: should be
rowIDs[i] = dataGrid.SelectedRows[i].Cells[0];
 
Error 2: should be
dataGrid.DoDragDrop(rowIDs, DragDropEffects.Link);

Author Comment

by:tomcahill

ID: 217546592008-06-10

great, now I get the error:

Error 1 Cannot implicitly convert type 'System.Windows.Forms.DataGridViewCell' to 'int' C:\Users\tom\Documents\Visual Studio 2008\Projects\IOPS\IOPS\Form1.cs 680 33 IOPS

on the line:

rowIDs[i] = dataGridView1.SelectedRows[i].Cells[0];

do I need to add .rowindex ??

Expert Comment

by:gbarcalow

ID: 217547042008-06-10

What does the data that you loading into the datagridview look like? What is your datasource and whats in it, and which fields are your keys?

Author Comment

by:tomcahill

ID: 218331732008-06-20

My datasource is a dataset loaded from a SQL table. The primary key, and only key, is a Column named CAT that is numeric. It is an Identity column.

Sorry for the delay in responding.

Accepted Solution

by:tomcahill

tomcahill earned 0 total points

ID: 219171522008-07-02

I found how to make it work.

my datagrid is named grdCampaigns

my treeview is named lstCategories

I create a 2 global variables as such:
bool dragdrop = false;

DataGridViewSelectedRowCollection myRows;

When I do the drag and drop I move the selected rows from the datagrid to the myRows variable. then in the drop I use that information to populate the treeview.

I will attach all of my code.

namespace Drag_Drop_Test
{
    public partial class Form1 : Form
    {
        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void mouse_event(long dwFlags, long dx, long dy, long cButtons, long dwExtraInfo);
 
        private const int MOUSEEVENTF_LEFTDOWN = 0x02;
        private const int MOUSEEVENTF_LEFTUP = 0x04;
        private const int MOUSEEVENTF_RIGHTDOWN = 0x08;
        private const int MOUSEEVENTF_RIGHTUP = 0x10;
        bool dragdrop = false;
 
        DataGridViewSelectedRowCollection myRows;
 
        
 
 
        public Form1()
        {
            InitializeComponent();
        }
 
        private void Form1_Load(object sender, EventArgs e)
        {
            // TODO: This line of code loads data into the 'iOPS_SandboxDataSet.CarrierMaster' table. You can move, or remove it, as needed.
            this.carrierMasterTableAdapter.Fill(this.iOPS_SandboxDataSet.CarrierMaster);
            
 
        }
 
        private void grdCampaigns_MouseDown(object sender, MouseEventArgs e)
        {
            DataGridView.HitTestInfo info = grdCampaigns.HitTest(e.X, e.Y);
            if (info.RowIndex >= 0)
            {
                DataRowView view = (DataRowView)
                grdCampaigns.Rows[info.RowIndex].DataBoundItem;
 
                if (view != null)
                    grdCampaigns.DoDragDrop(view, DragDropEffects.Copy);
            }
        }
 
        private void lstCategories_DragEnter(object sender, DragEventArgs e)
        {           
            e.Effect = DragDropEffects.Copy;
        }
 
         public void DoMouseClick()
        {
            
            //Call the imported function with the cursor's current position
            int X = Cursor.Position.X;
            int Y = Cursor.Position.Y;
            mouse_event(MOUSEEVENTF_LEFTDOWN | MOUSEEVENTF_LEFTUP, X, Y, 0, 0);
 
        }
 
        private void lstCategories_DragDrop(object sender, DragEventArgs e)
        {
            myRows = grdCampaigns.SelectedRows;
            DoMouseClick();
            dragdrop = true;
        }
 
        private void updateTree()
        {
            if(lstCategories.SelectedNode.Level == 2)
            {
                TreeNode selectedNode = lstCategories.SelectedNode;
            
                lstCategories.BeginUpdate();
                for (int i = 0; i < myRows.Count; i++)
            {
                selectedNode.Nodes.Add(myRows[i].Cells[1].Value.ToString());
            }
                lstCategories.EndUpdate();
                dragdrop = false;
                grdCampaigns.Refresh();
            }
            
        }
 
 
 
        private void lstCategories_NodeMouseHover(object sender, TreeNodeMouseHoverEventArgs e)
        {
            if (dragdrop)
            {
                updateTree();
            }
  
        }
 
        private void addSchemeToolStripMenuItem_Click(object sender, EventArgs e)
        {
            
            TreeNode baseNode = lstCategories.SelectedNode;
            baseNode.Nodes.Add("Scheme","Scheme");
            TreeNode schemeNode = baseNode.Nodes["Scheme"];
 
            string connectionString = Drag_Drop_Test.Properties.Settings.Default.IOPS_SandboxConnectionString;
 
            string selectString = "Select * from SchemeTypeMaster WHERE STYP = '1'";
 
            SqlConnection myConnection = new SqlConnection(connectionString);
            myConnection.Open();
 
            SqlCommand schemeCommand = new SqlCommand(selectString, myConnection);
            SqlDataReader schemeReader = schemeCommand.ExecuteReader();
 
            while (schemeReader.Read())
            {
                schemeNode.Nodes.Add(schemeReader["OLAN"].ToString().Trim(), schemeReader["LNAM"].ToString().Trim());
            }
            schemeCommand.Dispose();
            myConnection.Close();
            baseNode.ExpandAll();
            baseNode.ContextMenuStrip = null;
            
        }