Automatically check child nodes on a treeview

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I was to write a code for a treeview, so that when the user checks the adult node, the child node is automatically checked also. But nothing happens when I run it

private void treeView1_AfterCheck(object sender, TreeViewEventArgs e)
{
    // The code only executes if the user caused the checked state to change.
    if (e.Action != TreeViewAction.Unknown)
    {
        if (e.Node.Nodes.Count > 0)
        {
            /* Calls the CheckAllChildNodes method, passing in the current
            Checked value of the TreeNode whose checked state changed. */
            this.CheckAllChildNodes(e.Node, e.Node.Checked);
        }
    }
}

I keep on getting the error of...
CS1061 C# does not contain a definition for and no extension method accepting a first argument of type could be found (are you missing a using directive or an assembly reference?)

What I have tried:

private void treeView1_AfterSelect(object sender, TreeViewEventArgs e)
{
    treeView1.BeginUpdate();
    foreach (TreeNode tn in e.Node.Nodes)
        tn.Checked = e.Node.Checked;
    treeView1.EndUpdate();
}

Posted 23-Apr-18 4:00am

Member 13765884

Updated 23-Apr-18 9:44am

v2

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2 solutions

Solution 1

If I understand your question correctly, a sample code is provided in the documentation of AfterChec event. Have a look at TreeView.AfterCheck Event (System.Windows.Forms)[^]

Posted 23-Apr-18 6:00am

Wendelius

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Maciej Los · Accepted Answer · 2018-04-23T09:45:00

Compiler Error CS1061 | Microsoft Docs[^] occurs when you try to call a method or access a class member that does not exist.
Note that this.CheckAllChildNodes refer to Form class and you probably didn't define such of method. Add below methd to find out if error dissapear.

C#

// Updates all child tree nodes recursively.
private void CheckAllChildNodes(TreeNode treeNode, bool nodeChecked)
{
   foreach(TreeNode node in treeNode.Nodes)
   {
      node.Checked = nodeChecked;
      if(node.Nodes.Count > 0)
      {
         // If the current node has child nodes, call the CheckAllChildsNodes method recursively.
         this.CheckAllChildNodes(node, nodeChecked);
      }
   }
}