C# 基于XPath创建XML节点?
有人知道从XPath表达式编程创建XML层次结构的现有方法吗 例如,如果我有一个XML片段,例如:C# 基于XPath创建XML节点?,c#,xml,xpath,C#,Xml,Xpath,有人知道从XPath表达式编程创建XML层次结构的现有方法吗 例如,如果我有一个XML片段,例如: <feed> <entry> <data></data> <content></content> </entry> </feed> 给定XPath表达式/feed/entry/content/@source,我会: <feed>
<feed>
<entry>
<data></data>
<content></content>
</entry>
</feed>
给定XPath表达式/feed/entry/content/@source,我会:
<feed>
<entry>
<data></data>
<content @source=""></content>
</entry>
</feed>
我意识到使用XSLT可以做到这一点,但由于我试图实现的动态特性,固定转换无法工作
我在C#工作,但如果有人有使用其他语言的解决方案,请插话
谢谢你的帮助 在您展示的示例中,唯一要创建的是属性
XmlElement element = (XmlElement)doc.SelectSingleNode("/feed/entry/content");
if (element != null)
element.SetAttribute("source", "");
如果您真正想要的是能够在不存在层次结构的地方创建层次结构,那么您可以使用自己的简单xpath解析器。不过,我不知道如何将该属性保留在xpath中。我宁愿将节点强制转换为元素,并像我在这里所做的那样固定在.SetAttribute上:
static private XmlNode makeXPath(XmlDocument doc, string xpath)
{
return makeXPath(doc, doc as XmlNode, xpath);
}
static private XmlNode makeXPath(XmlDocument doc, XmlNode parent, string xpath)
{
// grab the next node name in the xpath; or return parent if empty
string[] partsOfXPath = xpath.Trim('/').Split('/');
string nextNodeInXPath = partsOfXPath.First();
if (string.IsNullOrEmpty(nextNodeInXPath))
return parent;
// get or create the node from the name
XmlNode node = parent.SelectSingleNode(nextNodeInXPath);
if (node == null)
node = parent.AppendChild(doc.CreateElement(nextNodeInXPath));
// rejoin the remainder of the array as an xpath expression and recurse
string rest = String.Join("/", partsOfXPath.Skip(1).ToArray());
return makeXPath(doc, node, rest);
}
static void Main(string[] args)
{
XmlDocument doc = new XmlDocument();
doc.LoadXml("<feed />");
makeXPath(doc, "/feed/entry/data");
XmlElement contentElement = (XmlElement)makeXPath(doc, "/feed/entry/content");
contentElement.SetAttribute("source", "");
Console.WriteLine(doc.OuterXml);
}
静态私有XmlNode makeXPath(XmlDocument文档,字符串xpath)
{
返回makeXPath(doc,docasxmlnode,xpath);
}
静态私有XmlNode makeXPath(XmlDocument文档、XmlNode父级、字符串xpath)
{
//获取xpath中的下一个节点名;如果为空,则返回parent
字符串[]partsOfXPath=xpath.Trim('/').Split('/');
字符串nextNodeInXPath=partsOfXPath.First();
if(string.IsNullOrEmpty(nextNodeInXPath))
返回父母;
//从名称获取或创建节点
xmlnodenode=parent.SelectSingleNode(nextNodeInXPath);
if(node==null)
node=parent.AppendChild(doc.CreateElement(nextNodeInXPath));
//将数组的其余部分作为xpath表达式重新连接并递归
string rest=string.Join(“/”,partsOfXPath.Skip(1.ToArray());
返回makeXPath(doc、node、rest);
}
静态void Main(字符串[]参数)
{
XmlDocument doc=新的XmlDocument();
doc.LoadXml(“”);
makeXPath(doc,“/feed/entry/data”);
XmlElement contentElement=(XmlElement)makeXPath(doc,“/feed/entry/content”);
contentElement.SetAttribute(“源”和“”);
Console.WriteLine(doc.OuterXml);
}
如果XPath字符串是从后向前处理的,那么处理非根XPath就更容易了,例如://a/b/c。。。它也应该支持Gordon的XPath语法,尽管我还没有尝试过
static private XmlNode makeXPath(XmlDocument doc, string xpath)
{
string[] partsOfXPath = xpath.Split('/');
XmlNode node = null;
for (int xpathPos = partsOfXPath.Length; xpathPos > 0; xpathPos--)
{
string subXpath = string.Join("/", partsOfXPath, 0, xpathPos);
node = doc.SelectSingleNode(subXpath);
if (node != null)
{
// append new descendants
for (int newXpathPos = xpathPos; newXpathPos < partsOfXPath.Length; newXpathPos++)
{
node = node.AppendChild(doc.CreateElement(partsOfXPath[newXpathPos]));
}
break;
}
}
return node;
}
静态私有XmlNode makeXPath(XmlDocument文档,字符串xpath)
{
字符串[]partsOfXPath=xpath.Split('/');
XmlNode=null;
对于(int-xpathPos=partsOfXPath.Length;xpathPos>0;xpathPos--)
{
string subXpath=string.Join(“/”,partsOfXPath,0,xpathPos);
node=doc.SelectSingleNode(子XPath);
如果(节点!=null)
{
//追加新的后代
for(int newXpathPos=xpathPos;newXpathPos
这是我的版本。希望这也能帮助别人
public static void Main(string[] args)
{
XmlDocument doc = new XmlDocument();
XmlNode rootNode = GenerateXPathXmlElements(doc, "/RootNode/FirstChild/SecondChild/ThirdChild");
Console.Write(rootNode.OuterXml);
}
private static XmlDocument GenerateXPathXmlElements(XmlDocument xmlDocument, string xpath)
{
XmlNode parentNode = xmlDocument;
if (xmlDocument != null && !string.IsNullOrEmpty(xpath))
{
string[] partsOfXPath = xpath.Split('/');
string xPathSoFar = string.Empty;
foreach (string xPathElement in partsOfXPath)
{
if(string.IsNullOrEmpty(xPathElement))
continue;
xPathSoFar += "/" + xPathElement.Trim();
XmlNode childNode = xmlDocument.SelectSingleNode(xPathSoFar);
if(childNode == null)
{
childNode = xmlDocument.CreateElement(xPathElement);
}
parentNode.AppendChild(childNode);
parentNode = childNode;
}
}
return xmlDocument;
}
下面是我的快速破解,只要使用
/configuration/appSettings/add[@key='name']/@value
等格式,就可以创建属性
static XmlNode createXPath(XmlDocument doc, string xpath)
{
XmlNode node=doc;
foreach (string part in xpath.Substring(1).Split('/'))
{
XmlNodeList nodes=node.SelectNodes(part);
if (nodes.Count>1) throw new ComponentException("Xpath '"+xpath+"' was not found multiple times!");
else if (nodes.Count==1) { node=nodes[0]; continue; }
if (part.StartsWith("@"))
{
var anode=doc.CreateAttribute(part.Substring(1));
node.Attributes.Append(anode);
node=anode;
}
else
{
string elName, attrib=null;
if (part.Contains("["))
{
part.SplitOnce("[", out elName, out attrib);
if (!attrib.EndsWith("]")) throw new ComponentException("Unsupported XPath (missing ]): "+part);
attrib=attrib.Substring(0, attrib.Length-1);
}
else elName=part;
XmlNode next=doc.CreateElement(elName);
node.AppendChild(next);
node=next;
if (attrib!=null)
{
if (!attrib.StartsWith("@")) throw new ComponentException("Unsupported XPath attrib (missing @): "+part);
string name, value;
attrib.Substring(1).SplitOnce("='", out name, out value);
if (string.IsNullOrEmpty(value) || !value.EndsWith("'")) throw new ComponentException("Unsupported XPath attrib: "+part);
value=value.Substring(0, value.Length-1);
var anode=doc.CreateAttribute(name);
anode.Value=value;
node.Attributes.Append(anode);
}
}
}
return node;
}
SplitOnce是一种扩展方法:
public static void SplitOnce(this string value, string separator, out string part1, out string part2)
{
if (value!=null)
{
int idx=value.IndexOf(separator);
if (idx>=0)
{
part1=value.Substring(0, idx);
part2=value.Substring(idx+separator.Length);
}
else
{
part1=value;
part2=null;
}
}
else
{
part1="";
part2=null;
}
}
样本:
public static void Set(XmlDocument doc, string xpath, string value)
{
if (doc==null) throw new ArgumentNullException("doc");
if (string.IsNullOrEmpty(xpath)) throw new ArgumentNullException("xpath");
XmlNodeList nodes=doc.SelectNodes(xpath);
if (nodes.Count>1) throw new ComponentException("Xpath '"+xpath+"' was not found multiple times!");
else if (nodes.Count==0) createXPath(doc, xpath).InnerText=value;
else nodes[0].InnerText=value;
}
e、 g
我喜欢Chris的版本,因为它处理XPath中的属性,而其他解决方案没有(尽管它没有处理我修复的路径中的“text()”)。 不幸的是,我不得不在VB应用程序中使用它,因此下面是它的转换:
Private Sub SplitOnce(ByVal value As String, ByVal separator As String, ByRef part1 As String, ByRef part2 As String)
If (value IsNot Nothing) Then
Dim idx As Integer = value.IndexOf(separator)
If (idx >= 0) Then
part1 = value.Substring(0, idx)
part2 = value.Substring(idx + separator.Length)
Else
part1 = value
part2 = Nothing
End If
Else
part1 = ""
part2 = Nothing
End If
End Sub
Private Function createXPath(ByVal doc As XmlDocument, ByVal xpath As String) As XmlNode
Dim node As XmlNode = doc
Dim part As String
For Each part In xpath.Substring(1).Split("/")
Dim nodes As XmlNodeList = node.SelectNodes(part)
If (nodes.Count > 1) Then
Throw New Exception("Xpath '" + xpath + "' was not found multiple times!")
ElseIf (nodes.Count = 1) Then
node = nodes(0)
Continue For
End If
If (part.EndsWith("text()")) Then
' treat this the same as previous node since this is really innertext
Exit For
ElseIf (part.StartsWith("@")) Then
Dim anode As XmlAttribute = doc.CreateAttribute(part.Substring(1))
node.Attributes.Append(anode)
node = anode
Else
Dim elName As String = Nothing
Dim attrib As String = Nothing
If (part.Contains("[")) Then
SplitOnce(part, "[", elName, attrib)
If (Not attrib.EndsWith("]")) Then
Throw New Exception("Unsupported XPath (missing ]): " + part)
End If
attrib = attrib.Substring(0, attrib.Length - 1)
Else
elName = part
End If
Dim nextnode As XmlNode = doc.CreateElement(elName)
node.AppendChild(nextnode)
node = nextnode
If (attrib IsNot Nothing) Then
If (Not attrib.StartsWith("@")) Then
Throw New Exception("Unsupported XPath attrib (missing @): " + part)
End If
Dim name As String = ""
Dim value As String = ""
SplitOnce(attrib.Substring(1), "='", name, value)
If (String.IsNullOrEmpty(value) Or Not value.EndsWith("'")) Then
Throw New Exception("Unsupported XPath attrib: " + part)
End If
value = value.Substring(0, value.Length - 1)
Dim anode As XmlAttribute = doc.CreateAttribute(name)
anode.Value = value
node.Attributes.Append(anode)
End If
End If
Next
Return node
End Function
我知道这是一条非常古老的线。。。但我只是尝试了同样的事情,并提出了下面的正则表达式,这不是完美的,但我发现更通用
/+([\w]+)(\[@([\w]+)='([^']*)'\])?|/@([\w]+)
字符串/configuration/appSettings/add[@key='name']/@value
应该解析为
找到14个匹配项:
开始=0,结束=14
组(0)=/配置
组(1)=配置
组(2)=空
组(3)=空
组(4)=空
组(5)=空
开始=14,结束=26
组(0)=/appSettings
组(1)=应用程序设置
组(2)=空
组(3)=空
组(4)=空
组(5)=空
开始=26,结束=43
组(0)=/add[@key='name']
组(1)=添加
组(2)=[@key='name']
组(3)=键
组(4)=名称
组(5)=空
开始=43,结束=50
组(0)=/@值
组(1)=空
组(2)=空
组(3)=空
组(4)=空
组(5)=值
也就是说我们有 组(0)=已忽略 组(1)=元素名称 组(2)=忽略 组(3)=过滤器属性名称 组(4)=过滤器属性值 下面是一个可以使用该模式的java方法
public static Node createNodeFromXPath(Document doc, String expression) throws XPathExpressionException {
StringBuilder currentPath = new StringBuilder();
Matcher matcher = xpathParserPattern.matcher(expression);
Node currentNode = doc.getFirstChild();
while (matcher.find()) {
String currentXPath = matcher.group(0);
String elementName = matcher.group(1);
String filterName = matcher.group(3);
String filterValue = matcher.group(4);
String attributeName = matcher.group(5);
StringBuilder builder = currentPath.append(currentXPath);
String relativePath = builder.toString();
Node newNode = selectSingleNode(doc, relativePath);
if (newNode == null) {
if (attributeName != null) {
((Element) currentNode).setAttribute(attributeName, "");
newNode = selectSingleNode(doc, relativePath);
} else if (elementName != null) {
Element element = doc.createElement(elementName);
if (filterName != null) {
element.setAttribute(filterName, filterValue);
}
currentNode.appendChild(element);
newNode = element;
} else {
throw new UnsupportedOperationException("The given xPath is not supported " + relativePath);
}
}
currentNode = newNode;
}
if (selectSingleNode(doc, expression) == null) {
throw new IllegalArgumentException("The given xPath cannot be created " + expression);
}
return currentNode;
}这种想法的一个问题是xpath“破坏”了信息 有无限多的xml树可以匹配许多XPath。现在,在某些情况下,如您给出的示例,有一个明显的最小xml树与xpath匹配,其中有一个使用“=”的谓词 但是,例如,如果谓词使用not equal或equal以外的任何其他算术运算符,则存在无限多的可能性。您可以尝试选择一个“规范的”xml树,它需要(比如)最少的位来表示 例如,假设您有xpath
/feed/entry/content[@source>0]
。现在,任何具有适当结构的xml树(其中节点内容具有值大于0的属性源)都将匹配,但有无限多的数字大于零。通过选择“最小”值(可能是1),您可以尝试规范化xml
Xpath谓词可以包含非常任意的算术表达式,因此要解决这个问题,即使不是不可能,也是相当困难的。你可以想象其中有一个巨大的方程,它必须反向求解才能得到与方程相匹配的值;但由于匹配值的数量可能是无限的(只要它真的是一个不等式而不是一个方程),就需要找到一个规范解
public static Node createNodeFromXPath(Document doc, String expression) throws XPathExpressionException {
StringBuilder currentPath = new StringBuilder();
Matcher matcher = xpathParserPattern.matcher(expression);
Node currentNode = doc.getFirstChild();
while (matcher.find()) {
String currentXPath = matcher.group(0);
String elementName = matcher.group(1);
String filterName = matcher.group(3);
String filterValue = matcher.group(4);
String attributeName = matcher.group(5);
StringBuilder builder = currentPath.append(currentXPath);
String relativePath = builder.toString();
Node newNode = selectSingleNode(doc, relativePath);
if (newNode == null) {
if (attributeName != null) {
((Element) currentNode).setAttribute(attributeName, "");
newNode = selectSingleNode(doc, relativePath);
} else if (elementName != null) {
Element element = doc.createElement(elementName);
if (filterName != null) {
element.setAttribute(filterName, filterValue);
}
currentNode.appendChild(element);
newNode = element;
} else {
throw new UnsupportedOperationException("The given xPath is not supported " + relativePath);
}
}
currentNode = newNode;
}
if (selectSingleNode(doc, expression) == null) {
throw new IllegalArgumentException("The given xPath cannot be created " + expression);
}
return currentNode;
/// <summary>
/// Makes the X path. Use a format like //configuration/appSettings/add[@key='name']/@value
/// </summary>
/// <param name="doc">The doc.</param>
/// <param name="xpath">The xpath.</param>
/// <returns></returns>
public static XmlNode createNodeFromXPath(XmlDocument doc, string xpath)
{
// Create a new Regex object
Regex r = new Regex(@"/+([\w]+)(\[@([\w]+)='([^']*)'\])?|/@([\w]+)");
// Find matches
Match m = r.Match(xpath);
XmlNode currentNode = doc.FirstChild;
StringBuilder currentPath = new StringBuilder();
while (m.Success)
{
String currentXPath = m.Groups[0].Value; // "/configuration" or "/appSettings" or "/add"
String elementName = m.Groups[1].Value; // "configuration" or "appSettings" or "add"
String filterName = m.Groups[3].Value; // "" or "key"
String filterValue = m.Groups[4].Value; // "" or "name"
String attributeName = m.Groups[5].Value; // "" or "value"
StringBuilder builder = currentPath.Append(currentXPath);
String relativePath = builder.ToString();
XmlNode newNode = doc.SelectSingleNode(relativePath);
if (newNode == null)
{
if (!string.IsNullOrEmpty(attributeName))
{
((XmlElement)currentNode).SetAttribute(attributeName, "");
newNode = doc.SelectSingleNode(relativePath);
}
else if (!string.IsNullOrEmpty(elementName))
{
XmlElement element = doc.CreateElement(elementName);
if (!string.IsNullOrEmpty(filterName))
{
element.SetAttribute(filterName, filterValue);
}
currentNode.AppendChild(element);
newNode = element;
}
else
{
throw new FormatException("The given xPath is not supported " + relativePath);
}
}
currentNode = newNode;
m = m.NextMatch();
}
// Assure that the node is found or created
if (doc.SelectSingleNode(xpath) == null)
{
throw new FormatException("The given xPath cannot be created " + xpath);
}
return currentNode;
}
/([\w]+)(?:(?:[\[])(@|)([\w]+)(?:([!=<>]+)(?:(?:(?:')([^']+)(?:'))|([^']+))|)(?:[]])|)|([.]+))
Group 1: Node name
Group 2: @ (or Empty, for non attributes)
Group 3: Attribute Key
Group 4: Attribute Value (if string)
Group 5: Attribute Value (if number)
Group 6: .. (dots, one or more)
public static XNode createNodeFromXPath(XElement elem, string xpath)
{
// Create a new Regex object
Regex r = new Regex(@"/*([a-zA-Z0-9_\.\-]+)(\[@([a-zA-Z0-9_\.\-]+)='([^']*)'\])?|/@([a-zA-Z0-9_\.\-]+)");
xpath = xpath.Replace("\"", "'");
// Find matches
Match m = r.Match(xpath);
XNode currentNode = elem;
StringBuilder currentPath = new StringBuilder();
while (m.Success)
{
String currentXPath = m.Groups[0].Value; // "/configuration" or "/appSettings" or "/add"
String elementName = m.Groups[1].Value; // "configuration" or "appSettings" or "add"
String filterName = m.Groups[3].Value; // "" or "key"
String filterValue = m.Groups[4].Value; // "" or "name"
String attributeName = m.Groups[5].Value; // "" or "value"
StringBuilder builder = currentPath.Append(currentXPath);
String relativePath = builder.ToString();
XNode newNode = (XNode)elem.XPathSelectElement(relativePath);
if (newNode == null)
{
if (!string.IsNullOrEmpty(attributeName))
{
((XElement)currentNode).Attribute(attributeName).Value = "";
newNode = (XNode)elem.XPathEvaluate(relativePath);
}
else if (!string.IsNullOrEmpty(elementName))
{
XElement newElem = new XElement(elementName);
if (!string.IsNullOrEmpty(filterName))
{
newElem.Add(new XAttribute(filterName, filterValue));
}
((XElement)currentNode).Add(newElem);
newNode = newElem;
}
else
{
throw new FormatException("The given xPath is not supported " + relativePath);
}
}
currentNode = newNode;
m = m.NextMatch();
}
// Assure that the node is found or created
if (elem.XPathEvaluate(xpath) == null)
{
throw new FormatException("The given xPath cannot be created " + xpath);
}
return currentNode;
}
public static XNode CreateNodeFromXPath(XElement elem, string xpath)
{
// Create a new Regex object
Regex r = new Regex(@"/*([a-zA-Z0-9_\.\-\:]+)(\[@([a-zA-Z0-9_\.\-]+)='([^']*)'\])?|/@([a-zA-Z0-9_\.\-]+)");
xpath = xpath.Replace("\"", "'");
// Find matches
Match m = r.Match(xpath);
XNode currentNode = elem;
StringBuilder currentPath = new StringBuilder();
XPathNavigator XNav = elem.CreateNavigator();
while (m.Success)
{
String currentXPath = m.Groups[0].Value; // "/ns:configuration" or "/appSettings" or "/add"
String NamespaceAndElementName = m.Groups[1].Value; // "ns:configuration" or "appSettings" or "add"
String filterName = m.Groups[3].Value; // "" or "key"
String filterValue = m.Groups[4].Value; // "" or "name"
String attributeName = m.Groups[5].Value; // "" or "value"
XNamespace nspace = "";
string elementName;
int p = NamespaceAndElementName.IndexOf(':');
if (p >= 0)
{
string ns = NamespaceAndElementName.Substring(0, p);
elementName = NamespaceAndElementName.Substring(p + 1);
nspace = XNav.GetNamespace(ns);
}
else
elementName = NamespaceAndElementName;
StringBuilder builder = currentPath.Append(currentXPath);
String relativePath = builder.ToString();
XNode newNode = (XNode)elem.XPathSelectElement(relativePath, XNav);
if (newNode == null)
{
if (!string.IsNullOrEmpty(attributeName))
{
((XElement)currentNode).Attribute(attributeName).Value = "";
newNode = (XNode)elem.XPathEvaluate(relativePath, XNav);
}
else if (!string.IsNullOrEmpty(elementName))
{
XElement newElem = new XElement(nspace + elementName);
if (!string.IsNullOrEmpty(filterName))
{
newElem.Add(new XAttribute(filterName, filterValue));
}
((XElement)currentNode).Add(newElem);
newNode = newElem;
}
else
{
throw new FormatException("The given xPath is not supported " + relativePath);
}
}
currentNode = newNode;
m = m.NextMatch();
}
// Assure that the node is found or created
if (elem.XPathEvaluate(xpath, XNav) == null)
{
throw new FormatException("The given xPath cannot be created " + xpath);
}
return currentNode;
}
var xDoc = new XDocument(new XElement("root",
new XElement("child1"),
new XElement("child2")));
CreateElement(xDoc, "/root/child3");
CreateElement(xDoc, "/root/child4[@year=32][@month=44]");
CreateElement(xDoc, "/root/child4[@year=32][@month=44]/subchild1");
CreateElement(xDoc, "/root/child4[@year=32][@month=44]/subchild1/subchild[@name='jon']");
CreateElement(xDoc, "/root/child1");
public static XDocument CreateElement(XDocument document, string xpath)
{
if (string.IsNullOrEmpty(xpath))
throw new InvalidOperationException("Xpath must not be empty");
var xNodes = Regex.Matches(xpath, @"\/[^\/]+").Cast<Match>().Select(it => it.Value).ToList();
if (!xNodes.Any())
throw new InvalidOperationException("Invalid xPath");
var parent = document.Root;
var currentNodeXPath = "";
foreach (var xNode in xNodes)
{
currentNodeXPath += xNode;
var nodeName = Regex.Match(xNode, @"(?<=\/)[^\[]+").Value;
var existingNode = parent.XPathSelectElement(currentNodeXPath);
if (existingNode != null)
{
parent = existingNode;
continue;
}
var attributeNames =
Regex.Matches(xNode, @"(?<=@)([^=]+)\=([^]]+)")
.Cast<Match>()
.Select(it =>
{
var groups = it.Groups.Cast<Group>().ToList();
return new { AttributeName = groups[1].Value, AttributeValue = groups[2].Value };
});
parent.Add(new XElement(nodeName, attributeNames.Select(it => new XAttribute(it.AttributeName, it.AttributeValue)).ToArray()));
parent = parent.Descendants().Last();
}
return document;
}