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()