Drag and Drop in C# Does Not Work

Question

I have a C# program that is attempting to do a drag and drop operation. The pro gram is trying to drag from data in a datagridview and drop it to a textbox. The datagridview is a single cell.

The Drag method:
private void dgv_Functions_MouseDown(object sender, MouseEventArgs e)
{
dgv_Functions.DoDragDrop(dgv_Functions.SelectedRows,
DragDropEffects.Copy);
}

The Drop method:
private void txt_Query_DragEnter(object sender, DragEventArgs e)
{
e.Effect = DragDropEffects.Copy ;
}

What happens the drag appears to work but the drop appears to but nothing is dropped. Can some explain to me why this does not work.

Answer 1

@Steve Clark , Welcome to Microsoft Q&A, we also need to set the textBox1_DragDrop event if we want to drag data from datagirdview to textbox.

Here is a code example you could refer to.

 private void Form1_Load(object sender, EventArgs e)  
        {  
            List<Student> list = new List<Student>();  
            list.Add(new Student { Name="test1" });  
            dataGridView1.DataSource=list;  
            dataGridView1.AllowDrop= true;  
            textBox1.AllowDrop= true;  
             
        }  
  
        private void textBox1_DragEnter(object sender, DragEventArgs e)  
        {  
            if (e.Data.GetDataPresent(typeof(DataGridViewSelectedRowCollection)))  
            {  
                e.Effect = DragDropEffects.Move;  
            }  
        }  
        private void dataGridView1_MouseDown(object sender, MouseEventArgs e)  
        {  
            dataGridView1.DoDragDrop(dataGridView1.SelectedRows, DragDropEffects.Move);  
        }  
        private void textBox1_DragDrop(object sender, DragEventArgs e)  
        {  
            DataGridViewSelectedRowCollection rows = (DataGridViewSelectedRowCollection)e.Data.GetData(typeof(DataGridViewSelectedRowCollection));  
  
            foreach (DataGridViewRow row in rows)  
            {  
                textBox1.Text = row.Cells[0].Value.ToString();  
                 
            }  
        }  

Note: Please select the datagirdview row first of all and do the dragdrop operation.

Tested result:

Best Regards,
Jack

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Answer 2

Please understand I am a beginner in C# and do not understand. I copied the code from your example to my PC and nothing happens. Could you explain it in simpler terms and provide an example? I have provided a copy of my code below. Thank you.

  public Form1()  
        {  
            InitializeComponent();  
        }  
        public class Student  
        {  
  
            public string Name { get; set; }  
  
        }  
        private void Form1_Load(object sender, EventArgs e)  
        {  
            List <Student> list = new List<Student>();  
            list.Add(new Student { Name = "test1" });  
            dgv_Functions.DataSource = list;  
            dgv_Functions.AllowDrop = true;  
            textBox1.AllowDrop = true;  
        }  
  
        private void textBox1_DragEnter(object sender, DragEventArgs e)  
        {  
            if (e.Data.GetDataPresent(typeof(DataGridViewSelectedRowCollection)))  
            {  
                e.Effect = DragDropEffects.Move;  
            }  
        }  
        private void dataGridView1_MouseDown(object sender, MouseEventArgs e)  
        {  
            dgv_Functions.DoDragDrop(dgv_Functions.SelectedRows, DragDropEffects.Move);  
  
        }  
        private void textBox1_DragDrop(object sender, DragEventArgs e)  
        {  
            DataGridViewSelectedRowCollection rows =   
            (DataGridViewSelectedRowCollection)e.Data.GetData(typeof(DataGridViewSelectedRowCollection));  
  
            foreach (DataGridViewRow row in rows)  
            {  
                textBox1.Text = row.Cells[0].Value.ToString();  
  
            }  
        }  
    }