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Object reference not set to an instance of an object.

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Object reference not set to an instance of an object.

 
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  #1
Jan 14th, 2009
Ah man , ive been adjusting the code so much ...

I am trying to make a treeview that display's all the directories and files on theserver (SO FAR SO GOOD) ...

Here's my code to retrieve Directories and files

C# Syntax (Toggle Plain Text) 
  1. public string[] GetFileList()
  2.         {
  3.             string[] downloadFiles;
  4.             StringBuilder result = new StringBuilder();
  5.             FtpWebRequest reqFTP;
  6.             try
  7.             {
  8.                 reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://" + txtftpServerName.Text + "/"));
  9.                 reqFTP.UseBinary = true;
  10.                 reqFTP.Credentials = new NetworkCredential(txtftpUserName.Text, txtftpPassword.Text);
  11.                 reqFTP.Method = WebRequestMethods.Ftp.ListDirectory;
  12.                 WebResponse response = reqFTP.GetResponse();
  13.                 StreamReader reader = new StreamReader(response.GetResponseStream());
  14.  
  15.                 string line = reader.ReadLine();
  16.                 while (line != null)
  17.                 {
  18.                     result.Append(line);
  19.                     result.Append("\n");
  20.                     line = reader.ReadLine();
  21.                 }
  22.                 result.Remove(result.ToString().LastIndexOf('\n'), 1);
  23.                 reader.Close();
  24.                 response.Close();
  25.  
  26.                 return result.ToString().Split('\n');
  27.             }
  28.             catch (Exception ex)
  29.             {
  30.                 System.Windows.Forms.MessageBox.Show(ex.Message);
  31.                 downloadFiles = null;
  32.                 return downloadFiles;
  33.             }
  34.         }
  35.  
  36. public string[] GetChildFileList()
  37.         {
  38.             string[] downloadFiles;
  39.             StringBuilder result = new StringBuilder();
  40.             FtpWebRequest reqFTP;
  41.             try
  42.             {
  43.                 reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://" + txtftpServerName.Text + "/" + treeView1.SelectedNode.Text + "/"));
  44.                 reqFTP.UseBinary = true;
  45.                 reqFTP.Credentials = new NetworkCredential(txtftpUserName.Text, txtftpPassword.Text);
  46.                 reqFTP.Method = WebRequestMethods.Ftp.ListDirectory;
  47.                 WebResponse response = reqFTP.GetResponse();
  48.                 StreamReader reader = new StreamReader(response.GetResponseStream());
  49.  
  50.                 string line = reader.ReadLine();
  51.                 while (line != null)
  52.                 {
  53.                     result.Append(line);
  54.                     result.Append("\n");
  55.                     line = reader.ReadLine();
  56.                 }
  57.                 result.Remove(result.ToString().LastIndexOf('\n'), 1);
  58.                 reader.Close();
  59.                 response.Close();
  60.  
  61.                 return result.ToString().Split('\n');
  62.             }
  63.             catch (Exception ex)
  64.             {
  65.                 System.Windows.Forms.MessageBox.Show(ex.Message);
  66.                 downloadFiles = null;
  67.                 return downloadFiles;
  68.             }
  69.         }

This works fine indevidually , but when i try to combine the two:

C# Syntax (Toggle Plain Text) 
  1.  
  2. private void btnDoIt_Click(object sender, EventArgs e)
  3.         {
  4.             string[] Parent_Name = GetFileList();
  5.             string[] Child_Name = GetChildFileList();
  6.  
  7.             treeView1.Nodes.Clear();
  8.             if (Parent_Name != null)
  9.             {
  10.                 /*          Parent Node             */
  11.                 foreach (string filename in Parent_Name)
  12.                 {
  13.                     TreeNode ParentNode = new TreeNode(filename);
  14.                     treeView1.Nodes.Add(ParentNode);
  15.  
  16.                     if (Parent_Name != null)
  17.                     {
  18.                         foreach (string filename2 in Child_Name)
  19.                         {
  20.                             TreeNode ChildNode = new TreeNode(filename2);
  21.                             ParentNode.Nodes.Add(ChildNode);
  22.                         }
  23.                     }
  24.                 }
  25.             }
  26.         }

i get an error stating that "Object reference not set to an instance of an object." (LENS ON [foreach (string filename2 in Child_Name)] )

Can anyone maybe give me a clue ?? i dont even know why its complaining because it aught to work...

Happy coding
Last edited by cVz; Jan 14th, 2009 at 10:51 am.
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Re: Object reference not set to an instance of an object.

 
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  #2
Jan 14th, 2009
It works with me! but try to debug, that's the one who you can fully trust in.
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Re: Object reference not set to an instance of an object.

 
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  #3
Jan 14th, 2009
Its almost certainly correct:

as you go to use Child_name, but you checked parent wasnt null, so child could be
Did I just hear "You gotta help us, Doc. We've tried nothin' and we're all out of ideas" ? Is this you? Dont let this be you! I will put in as much effort as you seem to.
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Re: Object reference not set to an instance of an object.

 
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  #4
Jan 14th, 2009
It also works proper with me, but have some thing, that you should look at:
1. You check Parent_Name 2 times. And second one is inside the first one. It looks like question: "Are you really sure that (Parent_Name != null)" ;P
c# Syntax (Toggle Plain Text) 
  1. treeView1.Nodes.Clear();
  2.             if (Parent_Name != null)
  3.             {
and
c# Syntax (Toggle Plain Text) 
  1. if (Parent_Name != null)
  2.                     {
  3.                         foreach (string filename2 in Child_Name)

2. I suppose you should do that:
c# Syntax (Toggle Plain Text) 
  1. treeView1.Nodes.Add(ParentNode);
after you fill with data the ChildNode of this ParentNode.


Good luck
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Re: Object reference not set to an instance of an object.

 
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  #5
Jan 14th, 2009
Which is what I said in a lot less of a post.
Did I just hear "You gotta help us, Doc. We've tried nothin' and we're all out of ideas" ? Is this you? Dont let this be you! I will put in as much effort as you seem to.
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Re: Object reference not set to an instance of an object.

 
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  #6
Jan 14th, 2009
Oh yeah sorry. First part is your's. Wasn't about to do things like that O.O ... it seems that I need rest a bit ;P
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Re: Object reference not set to an instance of an object.

 
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  #7
Jan 15th, 2009
Welll well well, i feel like a retard now hahahahahahahaha!!!

Although , thats not the problem...

The problem lies here

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string[] Child_Name = GetChildFileList();
for some reason (i think) the Uri does not change because you have to SELECT a node first...

So i did this 

private void btnDoIt_Click(object sender, EventArgs e)
        {
            string[] Parent_Name = GetFileList();
            

            treeView1.Nodes.Clear();
            if (Parent_Name != null)
            {

                /*          Parent Node             */
                foreach (string filename in Parent_Name)
                {
                    TreeNode ParentNode = new TreeNode(filename);
                    
                    // changed the GetChildFileList uri to 'reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://" + txtftpServerName.Text + "/" + txtShowDirectory.Text + "/"));'

                    txtShowDirectory.Text = filename;

                    string[] Child_Name = GetChildFileList();

                    if (Child_Name != null)
                    {
                        foreach (string filename2 in Child_Name)
                        {
                            TreeNode ChildNode = new TreeNode(filename2);
                            ParentNode.Nodes.Add(ChildNode);
                        }
                    }
                    treeView1.Nodes.Add(ParentNode);
                }
            }
        }

WORKS LIKE A BOMB!!!!!!!!

cept i still get an error on my try -> catch saying

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"The remote server returned an error: (550) File unavailable. (eg. File not found, unavailable)."
Obviously there is still some kind of error
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Re: Object reference not set to an instance of an object.

 
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  #8
Jan 15th, 2009
Look i know the problemo is this

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string[] Child_Name = GetChildFileList();

if (Child_Name != null)
{
foreach (string filename2 in Child_Name)
{
TreeNode ChildNode = new TreeNode(filename2);
ParentNode.Nodes.Add(ChildNode);
}
}
but i cant really bypass that one or can I ???
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Re: Object reference not set to an instance of an object.

 
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  #9
Jan 15th, 2009
Well if Child_name is null, then look at your function
Did I just hear "You gotta help us, Doc. We've tried nothin' and we're all out of ideas" ? Is this you? Dont let this be you! I will put in as much effort as you seem to.
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