[英]Retrieving XML value in C# from arbitary key path
I've got a project where I'm currently implementing support for reading values from an XML file via an arbitrary/user-defined path within the document's keys. 我有一个项目,目前正在实现通过文档键内的任意/用户定义路径从XML文件读取值的支持。
For example, if the document looks like this: 例如,如果文档如下所示:
<information>
<machine>
<foo></foo>
<name>
test machine
</name>
<bar>spam</bar>
</machine>
</information>
then the user might want to retrieve the value from the name
key in information/machine
. 那么用户可能想从
information/machine
的name
键检索值。
Is there a way using XDocument
/ XPath
that I can look up the values the user wants without knowing/coding in the schema for the document? 有没有一种方法可以使用
XDocument
/ XPath
来查找用户想要的值,而无需了解/编码文档的架构?
My initial thought was working through the document with a form of recursive function utilizing XElement
items, but I feel like there ought to be a simpler/cleaner solution that doesn't require me rolling my own lookup code. 我最初的想法是通过使用
XElement
项目的递归函数形式来处理文档,但是我觉得应该有一个更简单/更干净的解决方案,不需要我滚动自己的查找代码。
I also tried something along these lines 我也尝试了这些方法
var doc = XDocument.Load("C:\Path\to\XML\file.xml");
// Split the parent keys string
XElement elem = doc.Root.XPathSelectElement("path/to/key");
if (elem != null && elem.Attribute("wantedKeyName") != null)
replace = elem.Attribute("wantedKeyName").Value;
but elem
is always null. 但
elem
始终为空。 I'm assuming there's a problem with the way I'm defining my path or utilizing XPathSelectElement, but I haven't worked it out yet. 我假设我定义路径或使用XPathSelectElement的方式存在问题,但是我还没有解决。
static XmlNode SearchNode(XmlNodeList nodeList, string nodeName)
{
for (int i = 0; i < nodeList.Count; i++)
{
if (nodeList[i].Name == nodeName)
{
return nodeList[i];
}
if (nodeList[i].HasChildNodes)
{
XmlNode node = SearchNode(nodeList[i].ChildNodes, nodeName);
if (node != null)
{
return node;
}
}
}
return null;
}
static XmlNodeList SearchNodeByPath(XmlNodeList nodeList, string xPath)
{
for (int i = 0; i < nodeList.Count; i++)
{
var nodes = nodeList[i].SelectNodes(xPath);
if (nodes != null && nodes.Count > 0)
{
return nodes;
}
if (nodeList[i].HasChildNodes)
{
XmlNodeList innerNodes = SearchNodeByPath(nodeList[i].ChildNodes, xPath);
if (innerNodes != null && innerNodes.Count > 0)
{
return innerNodes;
}
}
}
return null;
}
this is using of methods : 这是使用方法:
var node = SearchNode(doc.ChildNodes, "compiler");
var node1 = SearchNodeByPath(doc.ChildNodes, "compilers/compiler");
I turns out my solution using XPathSelectElement
was the correct approach, I just had to prepend the path/to/key
string with //
. 我发现使用
XPathSelectElement
解决方案是正确的方法,我只需要在path/to/key
字符串前加上//
。
The following code I ended up using does that and strips off any whitespace around the outside of the value (in case the value is on a separate line than the opening tag. 我最终使用的以下代码将执行此操作,并去除了值外部的所有空白(如果值与开始标记不在同一行)。
// xml is a struct with the path to the parent node (path/to/key)
// and the key name to look up
// Split the parent keys string
XElement elem = doc.Root.XPathSelectElement("//" + xml.KeyPath);
if (elem != null && elem.Element(xml.Key) != null)
replace = elem.Element(xml.Key).Value.Trim();
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