创建可编辑的xml文档(之四) 删除、改名、插入操作
执行删除、改名、插入操作
实现了拖放操作就已经完了最难的部分，但是出于完整性考虑，还应该提供一些更好的基本的编辑功能。下面仅仅用四行代码就可以实现删除操作：
[C#]
string xpath_query =
buildXPathQuery(this.SelectedNode);
System.Xml.XmlNode node =
xml_document.DocumentElement.SelectSingleNode(
xpath_query);
node.ParentNode.RemoveChild(node);
SelectedNode.Remove();
[VB]
Dim xpath_query As String = _
buildXPathQuery(Me.SelectedNode)
Dim node As System.Xml.XmlNode = _
xml_document.DocumentElement.SelectSingleNode( _
xpath_query)
node.ParentNode.RemoveChild(node)
SelectedNode.Remove()
重命名操作需要更多的一些考虑，你可以调用buildXPathQuery 去查找那个文件夹正在被编辑，还有如何确定是哪一个属性，如何确定被显示名称相应的返回结构的元素或者子元素？这是一个误导的问题，XPath filte函数已经被定义了，你只需应用现面的转换就可以了：
[C#]
private void XmlTreeView_AfterLabelEdit(object sender,
System.Windows.Forms.NodeLabelEditEventArgs e)
{
string xpath_query = buildXPathQuery(e.Node);
System.Xml.XmlNode node =
xml_document.DocumentElement.SelectSingleNode(
xpath_query);
System.Xml.XmlNode label =
node.SelectSingleNode(xpath_filter);
label.Value = e.Label;
}
[VB]
Private Sub XmlTreeView_AfterLabelEdit( _
ByVal sender As Object, _
ByVal e As
System.Windows.Forms.NodeLabelEditEventArgs) _
Handles MyBase.AfterLabelEdit
Dim xpath_query As String = buildXPathQuery(e.Node)
Dim node As System.Xml.XmlNode = _
xml_document.DocumentElement.SelectSingleNode( _
xpath_query)
Dim label As System.Xml.XmlNode =
node.SelectSingleNode(xpath_filter)
label.Value = e.Label
End Sub
最后一个挑战就是如何按照需求创建一个新的文件夹。query filter 允许用户用一组文件夹而不是xml元素操作xml文档。这样对你想在那些文件夹周围进行移动很有帮助的，而且它还可以告诉在哪里插入一个文件夹，但是它不能告诉你这个文件夹应该包含什么东西，你应该猜测文档中的所有文件夹是否含有相同的结构或者内容。但是我们的目标是创建一个不需要任何预定的显示xml 方法。因此，我选择将这些怎人委托给应用程序控制。例如，客户端代码可以下面这样写：
[C#]
System.Xml.XmlDocument insert_fragment =
new System.Xml.XmlDocument();
insert_fragment.LoadXml(
"<product id='New Item'>" +
"<description/><ordercode/><price/>" +
"<image/></product>");
// The TreeView uses XmlInsertionNode to add
// a new folder to the tree's underlying XML
// document on request
xmlTreeView1.XmlInsertionNode =
insert_fragment.DocumentElement;
[VB]
Dim insert_fragment As New System.Xml.XmlDocument()
insert_fragment.LoadXml(" & _
"<product id='New Item'>" & _
"<description/><ordercode/>"<price/>" & _
"<image/></product>")
xmlTreeView1.XmlInsertionNode = _
insert_fragment.DocumentElement
treeview 控件可以缓存一个结构的副本，将它作为一个临时变量来创建一个新的文件夹集合。你所要做的仅仅是确保被定义得文件夹可以被filter query 识别，否则treeview 将不能显示它。因为对于我们操作的文档，xml通常是外部的（external）。在我使用它之前需要导入到文档中
[C#]
// First you need to clone the node template, and
// import it, because it originates from a different
// document
System.Xml.XmlNode copy_node = new_node.Clone();
System.Xml.XmlNode insert_node =
xml_document.ImportNode(copy_node, true);
// Next locate which node should be its parent, and
// insert it
string xpath_query =
buildXPathQuery(this.SelectedNode);
System.Xml.XmlNode node =
xml_document.DocumentElement.SelectSingleNode(
xpath_query);
node.AppendChild(insert_node);
// Finally, apply the xpath filter to determine what
// to display
System.Xml.XmlNode expr =
insert_node.SelectSingleNode(xpath_filter);
System.Windows.Forms.TreeNode new_child =
SelectedNode.Nodes.Add(expr.Value);
populateTreeControl(insert_node, new_child.Nodes);
// Select the node, to force the tree to expand
SelectedNode = new_child;
// And start editing the new folder name
suppress_label_edit = false;
new_child.BeginEdit();
[VB]
' First you need to clone the node template, and
' import it, because it originates from a different
' document.
Dim copy_node As System.Xml.XmlNode = new_node.Clone()
Dim insert_node As System.Xml.XmlNode = _
xml_document.ImportNode(copy_node, True)
' Next locate which node should be its parent,
' and insert it
Dim xpath_query As String = _
buildXPathQuery(Me.SelectedNode)
Dim node As System.Xml.XmlNode =
xml_document.DocumentElement.SelectSingleNode( _
xpath_query)
node.AppendChild(insert_node)
' Finally, apply the xpath filter to determine what
' should be
' displayed
Dim expr As System.Xml.XmlNode = _
insert_node.SelectSingleNode(xpath_filter)
Dim new_child As System.Windows.Forms.TreeNode = _
SelectedNode.Nodes.Add(expr.Value)
populateTreeControl(insert_node, new_child.Nodes)
' Select the node, to force the tree to expand
SelectedNode = new_child
' And start editing the new folder name
suppress_label_edit = False
new_child.BeginEdit()
