创build基于XPath的XML节点？
有没有人知道从XPathexpression式编程创buildXML层次结构的现有手段？
例如，如果我有一个XML片段，如：
<feed> <entry> <data></data> <content></content> </entry> </feed> 鉴于XPathexpression式/饲料/条目/内容/ @源我会有：
<feed> <entry> <data></data> <content @source=""></content> </entry> </feed>
我意识到这是可能的使用XSLT，但由于我试图完成固定转换的dynamic性质将无法正常工作。
我在C＃中工作，但如果有人使用其他语言的解决scheme，请join。
谢谢您的帮助！
在这个例子中，你现在唯一正在创build的是属性…
XmlElement element = (XmlElement)doc.SelectSingleNode("/feed/entry/content"); if (element != null) element.SetAttribute("source", "");
如果你真正想要的是能够创build它不存在的层次结构，那么你可以自己的简单的xpathparsing器。 我不知道在xpath中保留属性。 我宁愿将节点作为一个元素进行投射，并像我在这里所做的那样处理.SetAttribute：
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); }
这里是我的快速入侵，只要你使用像/configuration/appSettings/add[@key='name']/@value这样的格式，也可以创build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; } }
样品：
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; }
例如
Set(doc, "/configuration/appSettings/add[@key='Server']/@value", "foobar");
这个想法的一个问题是xpath“破坏”信息。
有无数的xml树可以匹配许多xpath。 现在在某些情况下，就像你给的例子，有一个明显的最小xml树匹配你的xpath，你有一个使用“=”的谓词。
但是，举例来说，如果谓词使用不等于或者除了相等的其他算术运算符，则存在无数的可能性。 你可以尝试select一个“规范的”xml树，这需要比方说最less的位来表示。
假设你有xpath /feed/entry/content[@source > 0] 。 现在，任何适当结构的xml树，其中节点内容的属性来源的值大于0，都会匹配，但是有无数个大于零的数字。 通过select“最小”的值，大概1，你可以试图规范你的XML。
Xpath谓词可以包含相当随意的算术expression式，所以这个通用的解决scheme相当困难，如果不是不可能的话。 你可以想象一个巨大的方程式，它必须相反地解决，才能得到与方程相匹配的值。 但是由于可以有无限多的匹配值（只要它是一个不等式而不是方程），就需要find一个规范的解决scheme。
其他forms的许多expression也破坏信息。 例如，像“或”这样的操作符总是会破坏信息。 如果知道(X or Y) == 1 ，则不知道X是1，Y是1，还是两者都是1; 所有你知道的是，其中一个是1！ 因此，如果你有一个使用OR的expression式，你不能分辨哪个节点或者input到OR的值应该是1（你可以做一个任意的select并且同时设置1，因为这样做肯定会满足expression式，这两个选项中只有一个是1）。
现在假设xpath中有几个expression式指向同一组值。 然后，你会得到一个几乎不可能解决的联立方程或不等式的系统。 同样，如果将可允许的xpath限制为其全部function的一小部分，则可以解决此问题。 然而，我怀疑这个完全一般的情况类似于图灵中断问题。 在这种情况下，给定一个任意程序（xpath），找出一组与程序匹配的一致数据，从某种意义上说是最小的。
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; }
Mark Miller的C＃版本
/// <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; }
如果XPathstring是从后到前处理的，则更容易处理非根XPath，例如。 // a / b / c …它应该也支持Gordon的XPath语法，虽然我还没有尝试过…
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; }
以下是基于Mark Miller的增强型RegEx：
/([\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)
我知道这是一个非常古老的线程…但我刚刚尝试相同的事情，并提出了以下正则expression式，这是不完美的，但我发现更通用的
/+([\w]+)(\[@([\w]+)='([^']*)'\])?|/@([\w]+)
string/configuration/ appSettings /添加[@键='名称'] / @值
应该被parsing为
发现14比赛：
（0）= /configuration组（1）=configuration组（2）=空组（3）=空组（4）=空组（5）=空
开始= 14，结束= 26组（0）= / appSettings组（1）= appSettings组（2）= null组（3）= null组（4）= null组（5）= null
（1）=添加组（2）= [@key ='name']组（3）=组（4）=组）=名称组（5）=空
（0）= / @值组（1）=空组（2）=空组（3）=空组（4）=空组（5）=值
这意味着我们有
组（0）=忽略组（1）=组件名称组（2）=忽略组（3）=filter属性名称组（4）=filter属性值
这里是一个可以使用模式的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;
}
这是Christian Peeters解决scheme的改进版本，它支持xpathexpression式中的命名空间。
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; }
我需要一个XNode而不是一个XmlNode实现，而RegEx对我来说不是工作的（因为具有。或 – 的元素名称不起作用）
所以这是什么对我有用：
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; }
- 对于XDocument
- 支持属性创build
定义
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; }
使用
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");
我喜欢克里斯的版本，因为它处理xpaths中的属性，其他解决scheme没有（尽pipe它没有处理好我固定的path中的“text（）”）。 我不幸的是不得不在VB应用程序中使用这个，所以这里的转换：
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
