Treeview selectednode problem/question

[David Elliott]

Hi,

I have a Windows Explorer-like treeview that displays directories. After a
cut/paste operation, I want the treeview to display the folder where the
paste happened. But, I'm running into a problem following the assignment of
the selectednode in the treeview. Here's the relevant code:

// separate the node names
string [] split = mcurrentPath.Sp lit(new Char [] {'\\'});

TreeNode currNode = null;

int currIndex = 0;

// find the Node for this node name
foreach (string s in split)
{
if (currIndex == 0)
// we're on the top-most node
currNode = tvwDirectory.To pNode;

// search the current node's nodes for this text
foreach (TreeNode n in currNode.Nodes)
{
if (n.Text == s)
{
currNode = n;
break;
}
}
currIndex++;
}

tvwDirectory.Be ginUpdate();
tvwDirectory.Se lectedNode = null;
tvwDirectory.No des.Clear();
FilltreeView();
tvwDirectory.Se lectedNode = currNode;
tvwDirectory.Se lectedNode.Expa nd(); <-- this is where I blow up!
tvwDirectory.En dUpdate();

I've looked at currNode using the debugger and it looks OK. But, on the
Expand() I get this error:
System.NullRefe renceException: Object reference not set to an instance of
an object.

Any help will be most appreciated.

Thanks,

--
Dave

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[AlexS]

Hi, David

curnode cannot be for selection after you clear list of nodes in treeview.
It's not present anymore in treeview.

HTH
Alex

"David Elliott" <David_Elliott@ no_spam_excite. com> wrote in message
news:Xn******** ********@24.93. 43.121...

Hi,

I have a Windows Explorer-like treeview that displays directories. After a
cut/paste operation, I want the treeview to display the folder where the
paste happened. But, I'm running into a problem following the assignment of the selectednode in the treeview. Here's the relevant code:

// separate the node names
string [] split = mcurrentPath.Sp lit(new Char [] {'\\'});

TreeNode currNode = null;

int currIndex = 0;

// find the Node for this node name
foreach (string s in split)
{
if (currIndex == 0)
// we're on the top-most node
currNode = tvwDirectory.To pNode;

// search the current node's nodes for this text
foreach (TreeNode n in currNode.Nodes)
{
if (n.Text == s)
{
currNode = n;
break;
}
}
currIndex++;
}

tvwDirectory.Be ginUpdate();
tvwDirectory.Se lectedNode = null;
tvwDirectory.No des.Clear();
FilltreeView();
tvwDirectory.Se lectedNode = currNode;
tvwDirectory.Se lectedNode.Expa nd(); <-- this is where I blow up!
tvwDirectory.En dUpdate();

I've looked at currNode using the debugger and it looks OK. But, on the
Expand() I get this error:
System.NullRefe renceException: Object reference not set to an instance of
an object.

Any help will be most appreciated.

Thanks,

--
Dave

remove n_o and s_p_a_m to reply directly

[Frans Bouma [C# MVP]]

David Elliott wrote:

I have a Windows Explorer-like treeview that displays directories. After a
cut/paste operation, I want the treeview to display the folder where the
paste happened. But, I'm running into a problem following the assignment of
the selectednode in the treeview. Here's the relevant code:

// separate the node names
string [] split = mcurrentPath.Sp lit(new Char [] {'\\'});

TreeNode currNode = null;

int currIndex = 0;

// find the Node for this node name
foreach (string s in split)
{
if (currIndex == 0)
// we're on the top-most node
currNode = tvwDirectory.To pNode;

// search the current node's nodes for this text
foreach (TreeNode n in currNode.Nodes)
{
if (n.Text == s)
{
currNode = n;
break;
}
}
currIndex++;
}

tvwDirectory.Be ginUpdate();
tvwDirectory.Se lectedNode = null;
tvwDirectory.No des.Clear();
^^^^^^^
this will clear all nodes. So whatever value currNode is pointing to, it's
not a node in the tree anymore.
FilltreeView();
^^^^^^^^
Here you add NEW nodes.
tvwDirectory.Se lectedNode = currNode;
^^^^^^^^
Here you're setting the SelectedNode property to a node object that's NOT
part of the tree, as you cleared all.
tvwDirectory.Se lectedNode.Expa nd(); <-- this is where I blow up!
tvwDirectory.En dUpdate();

I've looked at currNode using the debugger and it looks OK. But, on the
Expand() I get this error:
System.NullRefe renceException: Object reference not set to an instance of
an object.

of course, it can't find the node in the tree. :)

FB

--
Get LLBLGen Pro, the new O/R mapper for .NET: http://www.llblgen.com
My .NET Blog: http://weblogs.asp.net/fbouma
Microsoft C# MVP

[Smokin Dave]

Hi Alex,

Thanks very much. That helped.

Regards,

David
"AlexS" <sa***********@ SPAMsympaticoPL EASE.ca> wrote in
news:OQ******** ******@TK2MSFTN GP09.phx.gbl:

Hi, David

curnode cannot be for selection after you clear list of nodes in
treeview. It's not present anymore in treeview.

HTH
Alex

"David Elliott" <David_Elliott@ no_spam_excite. com> wrote in message
news:Xn******** ********@24.93. 43.121...

Hi,

I have a Windows Explorer-like treeview that displays directories.
After a cut/paste operation, I want the treeview to display the
folder where the paste happened. But, I'm running into a problem
following the assignment

of

the selectednode in the treeview. Here's the relevant code:

// separate the node names
string [] split = mcurrentPath.Sp lit(new Char [] {'\\'});

TreeNode currNode = null;

int currIndex = 0;

// find the Node for this node name
foreach (string s in split)
{
if (currIndex == 0)
// we're on the top-most node
currNode = tvwDirectory.To pNode;

// search the current node's nodes for this text
foreach (TreeNode n in currNode.Nodes)
{
if (n.Text == s)
{
currNode = n;
break;
}
}
currIndex++;
}

tvwDirectory.Be ginUpdate();
tvwDirectory.Se lectedNode = null;
tvwDirectory.No des.Clear();
FilltreeView();
tvwDirectory.Se lectedNode = currNode;
tvwDirectory.Se lectedNode.Expa nd(); <-- this is where I blow up!
tvwDirectory.En dUpdate();

I've looked at currNode using the debugger and it looks OK. But, on
the Expand() I get this error:
System.NullRefe renceException: Object reference not set to an
instance of an object.

Any help will be most appreciated.

Thanks,

--
Dave

remove n_o and s_p_a_m to reply directly

--
Dave

remove n_o and s_p_a_m to reply directly

[Smokin Dave]

Thanks Frans. You are correct on all counts.

I've changed it around a bit and it's working much better now.

Regards,

David
"Frans Bouma [C# MVP]" <pe************ ******@xs4all.n l> wrote in
news:xn******** *******@msnews. microsoft.com:

David Elliott wrote:

I have a Windows Explorer-like treeview that displays directories.
After a cut/paste operation, I want the treeview to display the
folder where the paste happened. But, I'm running into a problem
following the assignment of the selectednode in the treeview. Here's
the relevant code:

// separate the node names
string [] split = mcurrentPath.Sp lit(new Char [] {'\\'});

TreeNode currNode = null;

int currIndex = 0;

// find the Node for this node name
foreach (string s in split)
{
if (currIndex == 0)
// we're on the top-most node
currNode = tvwDirectory.To pNode;

// search the current node's nodes for this text
foreach (TreeNode n in currNode.Nodes)
{
if (n.Text == s)
{
currNode = n;
break;
}
}
currIndex++;
}

tvwDirectory.Be ginUpdate();
tvwDirectory.Se lectedNode = null;
tvwDirectory.No des.Clear();

^^^^^^^
this will clear all nodes. So whatever value currNode is pointing
to, it's
not a node in the tree anymore.

FilltreeView();

^^^^^^^^
Here you add NEW nodes.

tvwDirectory.Se lectedNode = currNode;

^^^^^^^^
Here you're setting the SelectedNode property to a node object
that's NOT
part of the tree, as you cleared all.

tvwDirectory.Se lectedNode.Expa nd(); <-- this is where I blow up!
tvwDirectory.En dUpdate();

I've looked at currNode using the debugger and it looks OK. But, on
the Expand() I get this error:
System.NullRefe renceException: Object reference not set to an
instance of an object.

of course, it can't find the node in the tree. :)

FB

--
Dave

remove n_o and s_p_a_m to reply directly