[SOLVED] Drag and drop file explorer - C# Discussion Boards

28-Apr-16 2:47

Hello

I'd like to do a file explorer. With the Microsoft tutorial i created a form with two treeviews and two listboxes. Now i want to copy files be drag and drop from one to the other listbox. liw_Source is my first Listbox. Here i want to select the files and drag it to liw_Target. In liw_Target there should the files be pasted.

The File is shown in the secont Listbox. But restarting the application, the file isn't copied. How do i copy the file?

My code:

private void liw_Source_ItemDrag(object sender, ItemDragEventArgs e)
{
    string s = e.Item.ToString();
    DoDragDrop(s, DragDropEffects.Copy | DragDropEffects.Move);
}

private void liw_Target_DragEnter(object sender, DragEventArgs e)
{

if (e.Data.GetDataPresent(DataFormats.Text))
    e.Effect = DragDropEffects.Copy;
else
    e.Effect = DragDropEffects.None;
}

private void liw_Target_DragDrop(object sender, DragEventArgs e)
{
    string typestring = "Type";
string s = e.Data.GetData(typestring.GetType()).ToString();
string orig_string = s;
s = s.Substring(s.IndexOf(":") + 1).Trim();
s = s.Substring(1, s.Length - 2);

this.liw_Target.Items.Add(s);

IEnumerator enumerator = liw_Source.Items.GetEnumerator();
int whichIdx = -1;
int idx = 0;
while (enumerator.MoveNext()) {
    string s2 = enumerator.Current.ToString();
    if (s2.Equals(orig_string)) {
        whichIdx = idx;
        break;
    }
    idx++;
}
this.liw_Source.Items.RemoveAt(whichIdx);

}

Thanks for your Help.

modified 29-Apr-16 3:27am.

OriginalGriff28-Apr-16 3:02

28-Apr-16 3:02

Well...you are dragging between boxes, but you aren't doing anything with the underlying files!
Look at the File.Move Method (String, String) (System.IO)[^] and transfer the files as well!

Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

AndrewRue28-Apr-16 3:11

28-Apr-16 3:11

Now i've implemented a file.copy method. But my Variable SourceName wich contains the filename is always null. By debugging with breakpoint it works but without brakepoints it's always null. Any Idea how i can select the source file?

private void liw_Source_DragDrop(object sender, DragEventArgs e)
{
    ListView files = (ListView)e.Data.GetData(typeof(ListView));
}

private void liw_Source_ItemDrag(object sender, ItemDragEventArgs e)
{
    liw_Source.DoDragDrop(e.Item, DragDropEffects.Copy);
    SourceName = e.Item.ToString();
    int start = SourceName.IndexOf("{") + 1;
    int end = SourceName.IndexOf("}");
    TargetName = SourceName.Substring(start, end - start);
}

private void liw_Target_DragEnter(object sender, DragEventArgs e)
{
    e.Effect = DragDropEffects.Copy;
}

private void liw_Target_DragDrop(object sender, DragEventArgs e)
{


    File.Copy(SourcePath + SourceName, TargetPath + SourceName, true);
}

OriginalGriff28-Apr-16 3:26

28-Apr-16 3:26

When I do drag and/or drop with files, I use a collection of actual files, just like the "regular" Windows Explorer does - there's even a DataFormat for them!

Keep your drag and drop separate: your Drop is relying on the ItemDrag event of your Source setting up your names appropriately. Don't do that: Make the source provide the info, and the Destination accept them.
The way I accept them is like this:

/// <summary>
/// USer dropped something on the form
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void frmMusicTrackRename_DragDrop(object sender, DragEventArgs e)
    {
    string[] files = (string[])e.Data.GetData(DataFormats.FileDrop);
    dgvTracks.Rows.Clear();
    LoadFiles(files);
    }

(It's part of something I wrote when I realised my music collection had three different track naming styles, and wanted to unify them.)

And don't use string concatenation to assemble a full path - use Path.Combine Method (System.IO)[^] instead as it will apply the separaters intelligently.

Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

AndrewRue28-Apr-16 19:50

28-Apr-16 19:50

This is working by adding files from Windows Explorer to the list view. But when i add a "File" from another listview it doesn't work. The path from the Files is always null. In my first listview i have not the file itself. It's only a graphic wich represents the file.

Any further ideas?

Thanks

OriginalGriff28-Apr-16 20:54

28-Apr-16 20:54

That would be because you aren't dragging them out of your listview as files - you are setting text format instead.
If you use the DataFormats.FileDrop Field (System.Windows)[^] it will allow you to drag them from your list box into anything which accepts files (inclding Explorer, Chrome, Word, ...)
It's not difficult!
Handle the MouseDown event for your ListView (this uses a DataGridView because I had one handy with files in a current project, and uses the right mouse button so I don't muck up my other code!)

private void myDataGridView_MouseDown(object sender, MouseEventArgs e)
    {
    if (e.Button == MouseButtons.Right)
        {
        List<string> files = new List<string>();
        foreach (DataGridViewRow row in myDataGridView.Rows)
            {
            files.Add((string)row.Cells["Location"].Value);
            }
        string[] selectedFiles = files.ToArray();
        // Load files as multiple types: Files (all) and Text (first one only)
        DataObject dragData = new DataObject(DataFormats.FileDrop, selectedFiles);
        dragData.SetData(DataFormats.StringFormat, selectedFiles[0]);
        DoDragDrop(dragData, DragDropEffects.Copy | DragDropEffects.Move);
        }
    }

That sets the list of files into the drag as files - you can now drop them on anything that accepts files!

Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

AndrewRue28-Apr-16 21:27

28-Apr-16 21:27

Working fine!

Thanks again.

OriginalGriff28-Apr-16 22:44

28-Apr-16 22:44

You're welcome!

Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

Shouldnt this work?

David Reeves27-Apr-16 12:25

David Reeves

27-Apr-16 12:25

foreach (DataRow dataRow in dt.Rows)
            {
                if (dataRow["Column1"].ToString().Contains(["ExampleString"])
                {
                    
                    listBox1.Items.Add(dataRow["Column1"] + " " + dataRow["Column2"] + "  " + dataRow["Column3"] + " " + dataRow["Column4"]);

                }
            }


//the above code works perfectly and returns only the rows containing the "ExampleString"


// if i try to use a SelectedText value from a combobox as a string to replace the "ExampleString", (as shown below),the listbox populates with ALL of the rows, not just the ones with the "ExampleString".  




string strFromCombobox = comboBox1.SelectedText;

foreach (DataRow dataRow in dt.Rows)
            {
                if (dataRow["Column1"].ToString().Contains(strFromCombobox)
                {
                    
                    listBox1.Items.Add(dataRow["Column1"] + " " + dataRow["Column2"] + "  " + dataRow["Column3"] + " " + dataRow["Column4"]);

                }
            }

Dave Kreskowiak27-Apr-16 13:54

Dave Kreskowiak

27-Apr-16 13:54

This is where you learn to use the debugger. Set a breakpoint on the if statement and inspect the contents of the strFromCombobox varaible. The debugger is there to show you how the code actually works instead of you guessing at it.

We really can't tell you why it fails because we can't see the contents of that variable. What every it is, it's matching content in Column1 of every row.

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Seriously, do it.

Dave Kreskowiak

Brisingr Aerowing27-Apr-16 14:21

Brisingr Aerowing

27-Apr-16 14:21

Likely not. SelectedText is the text the user has selected in the editable portion. I am guessing this is WinForms, so the property you want is SelectedItem[^], although you will need to cast it to a string.

This is all I can really do, as we don't know what type of object is in the combobox. If it's a string, great. Otherwise more logic may be needed.

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The metaphorical solid rear-end expulsions have impacted the metaphorical motorized bladed rotating air movement mechanism.

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David Reeves27-Apr-16 14:40

David Reeves

27-Apr-16 14:40

This is the code. The value has been changed to selecteditem but still not working

SqlDataAdapter da = new SqlDataAdapter();
            DataSet1 ds = new DataSet1();
            DataTable dt = new DataTable();
            string tm = comboBox1.SelectedItem.ToString();
            da.SelectCommand = cmd;
            da.Fill(ds, "GameResults2015");
            dt = ds.Tables["GameResults2015"];
            MessageBox.Show(tm);
            foreach (DataRow dataRow in dt.Rows)
            {
                if (dataRow["Winner/tie"].ToString().Contains(tm) || dataRow["Loser/tie"].ToString().Contains(tm))
                {
                    
                    listBox1.Items.Add(dataRow["Winner/tie"] + " " + dataRow["PtsW"] + " Loser " + dataRow["Loser/tie"] + " " + dataRow["PtsL"]);

                }
            }

Philippe Mori27-Apr-16 15:57

Philippe Mori

27-Apr-16 15:57

I guess you need to also remove items that do not contains the selected string.

Philippe Mori

Sascha Lefèvre27-Apr-16 21:27

Sascha Lefèvre

27-Apr-16 21:27

You really should follow Dave's advice and start using the debugger. Using the debugger isn't a crazy idea, it's what almost every developer does on a regular, if not even on a daily basis. It is essential to being as productive as possible as a developer - you would probably already know the solution to your problem here if you had used the debugger instead of writing the question.

So.. place a debug-breakpoint on that if-statement, hit F5 and when your program reaches that breakpoint, inspect the value of the variable(s) in question by hovering with the mouse cursor over it. That's all - neither difficult nor dangerous Big Grin | :-D

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