目前我正在处理这种类型的XML：XML FILE
参考XML文件，我想检查一个节点，如果找不到该节点，我必须将该节点附加到该文件。我尝试了以下代码：
private void button12_Click(object sender, EventArgs e)
{
// XmlNodeList func_name_value = doc.GetElementsByTagName("FUNCTION-NAME-VALUE");
XmlNodeList list_def_ref = doc.GetElementsByTagName("DEFINITION-REF");
foreach (XmlNode nodeDef in list_def_ref)
{
if (nodeDef.InnerText == "/AUTOSAR/Com/ComConfig/ComSignal")
{
if (nodeDef.ParentNode.HasChildNodes)
{
XmlNodeList list = nodeDef.ParentNode.ChildNodes;
foreach (XmlNode node in list)
{
if (node.Name == "PARAMETER-VALUES")
{
XmlNodeList param_list = node.ChildNodes;
foreach (XmlNode paramNode in param_list)
{
if (paramNode.Name == "FUNCTION-NAME-VALUE")
{
XmlNodeList func_child_list = paramNode.ChildNodes;
foreach (XmlNode funChild in func_child_list)
{
if (funChild.Name == "DEFINITION-REF")
{
string tout = "/AUTOSAR/Com/ComConfig/ComSignal/ComTimeoutNotification";
string comnotify = "/AUTOSAR/Com/ComConfig/ComSignal/ComNotification";
string invalid = "/AUTOSAR/Com/ComConfig/ComSignal/ComInvalidNotification";
if (funChild.InnerText != tout)
{
if (funChild.InnerText != comnotify)
{
//ADD ComInvalidNotification tags
XmlNode newNode = doc.CreateElement("FUNCTION-NAME-VALUE");
paramNode.AppendChild(newNode);
XmlNode defRefNode = doc.CreateElement("DEFINITION-REF");
XmlAttribute attr = doc.CreateAttribute("DEST");
attr.Value = "FUNCTION-NAME-DEF";
defRefNode.Attributes.SetNamedItem(attr);
newNode.AppendChild(defRefNode);
XmlNode val = doc.CreateElement("VALUE");
val.InnerText = "ComInvalidNotification";//ComInvalidNotification + shortName ;
newNode.AppendChild(val);
}
else
{
//ADD ComNotification tags
XmlNode newNode = doc.CreateElement("FUNCTION-NAME-VALUE");
paramNode.AppendChild(newNode);
XmlNode defRefNode = doc.CreateElement("DEFINITION-REF");
XmlAttribute attr = doc.CreateAttribute("DEST");
attr.Value = "FUNCTION-NAME-DEF";
defRefNode.Attributes.SetNamedItem(attr);
newNode.AppendChild(defRefNode);
XmlNode val = doc.CreateElement("VALUE");
val.InnerText = "ComNotification Node";//ComNotification + shortName;
newNode.AppendChild(val);
}
}
else
{
//ADD ComTimeOutNotification tags
XmlNode newNode = doc.CreateElement("FUNCTION-NAME-VALUE");
paramNode.AppendChild(newNode);
XmlNode defRefNode = doc.CreateElement("DEFINITION-REF");
XmlAttribute attr = doc.CreateAttribute("DEST");
attr.Value = "FUNCTION-NAME-DEF";
defRefNode.Attributes.SetNamedItem(attr);
newNode.AppendChild(defRefNode);
XmlNode val = doc.CreateElement("VALUE");
val.InnerText = "ComTimeoutNotification node";//ComInvalidNotification + shortName;
newNode.AppendChild(val);
}
}
}
}
}
}
}
}
}
}
doc.Save(openFileDialog1.FileName);
我得到的错误是：元素列表已更改。枚举操作无法继续。
在第一次执行foreach循环后，我收到此错误，我应该如何克服此错误？
答案 0 :(得分：2)
这里有两个问题：
您正在修改XmlNodeList个集合，同时迭代它们。 Microsoft在迭代期间修改集合时抛出异常是标准惯例，请参阅IEnumerator.MoveNext的文档：
<强>例外
InvalidOperationException：在创建枚举数后修改了集合。
要避免此异常，您可以手动使用for循环并通过XmlNodeList索引，或snapshot to a static List<T> and iterate through that。
您正在搜索名为<DEFINITION-REF>和<FUNCTION-NAME-VALUE>的XML节点，但您也使用此名称创建节点。这意味着您在迭代早期创建的节点可能会在迭代后期找到，从而导致更多节点的递归创建。我估计你不想要这个。如果我的计算是正确的，您应该快照所有满足搜索条件的节点，然后遍历快照，如下所示：
private static void AddMissingNodes(XmlDocument doc)
{
var query = from nodeDef in doc.GetElementsByTagName("DEFINITION-REF").Cast<XmlNode>()
where nodeDef.InnerText == "/AUTOSAR/Com/ComConfig/ComSignal"
from nodeDefSibling in nodeDef.ParentNode.ChildNodes.Cast<XmlNode>()
where nodeDefSibling.Name == "PARAMETER-VALUES"
from paramNode in nodeDefSibling.ChildNodes.Cast<XmlNode>()
where paramNode.Name == "FUNCTION-NAME-VALUE"
select new
{
paramNode = paramNode,
func_child_list = (from funChild in paramNode.ChildNodes.Cast<XmlNode>()
where funChild.Name == "DEFINITION-REF"
select funChild).ToList() // Snapshot func_child_list by calling ToList()
};
foreach (var paramNodeAndFuncChildren in query.ToList()) // Snapshot everything by calling ToList()
foreach (var funChild in paramNodeAndFuncChildren.func_child_list)
AddMissingNodes(doc, paramNodeAndFuncChildren.paramNode, funChild);
}
private static void AddMissingNodes(XmlDocument doc, XmlNode paramNode, XmlNode funChild)
{
string tout = "/AUTOSAR/Com/ComConfig/ComSignal/ComTimeoutNotification";
string comnotify = "/AUTOSAR/Com/ComConfig/ComSignal/ComNotification";
string invalid = "/AUTOSAR/Com/ComConfig/ComSignal/ComInvalidNotification";
if (funChild.InnerText != tout)
{
if (funChild.InnerText != comnotify)
{
//ADD ComInvalidNotification tags
XmlNode newNode = doc.CreateElement("FUNCTION-NAME-VALUE");
paramNode.AppendChild(newNode);
XmlNode defRefNode = doc.CreateElement("DEFINITION-REF");
XmlAttribute attr = doc.CreateAttribute("DEST");
attr.Value = "FUNCTION-NAME-DEF";
defRefNode.Attributes.SetNamedItem(attr);
newNode.AppendChild(defRefNode);
XmlNode val = doc.CreateElement("VALUE");
val.InnerText = "ComInvalidNotification";//ComInvalidNotification + shortName ;
newNode.AppendChild(val);
}
else
{
//ADD ComNotification tags
XmlNode newNode = doc.CreateElement("FUNCTION-NAME-VALUE");
paramNode.AppendChild(newNode);
XmlNode defRefNode = doc.CreateElement("DEFINITION-REF");
XmlAttribute attr = doc.CreateAttribute("DEST");
attr.Value = "FUNCTION-NAME-DEF";
defRefNode.Attributes.SetNamedItem(attr);
newNode.AppendChild(defRefNode);
XmlNode val = doc.CreateElement("VALUE");
val.InnerText = "ComNotification Node";//ComNotification + shortName;
newNode.AppendChild(val);
}
}
else
{
//ADD ComTimeOutNotification tags
XmlNode newNode = doc.CreateElement("FUNCTION-NAME-VALUE");
paramNode.AppendChild(newNode);
XmlNode defRefNode = doc.CreateElement("DEFINITION-REF");
XmlAttribute attr = doc.CreateAttribute("DEST");
attr.Value = "FUNCTION-NAME-DEF";
defRefNode.Attributes.SetNamedItem(attr);
newNode.AppendChild(defRefNode);
XmlNode val = doc.CreateElement("VALUE");
val.InnerText = "ComTimeoutNotification node";//ComInvalidNotification + shortName;
newNode.AppendChild(val);
}
}
然后，如果我count the number of XML nodes之前和之后：
var fileName = @"D:\Temp\Question36740480\autosar_ecucvalues_Fx4_L.xml";
var newFileName = @"D:\Temp\Question36740480\autosar_ecucvalues_Fx4_L_NEW.xml";
var doc = new XmlDocument();
doc.Load(fileName);
int countBefore = doc.SelectNodes("descendant::*").Count;
AddMissingNodes(doc);
int countAfter = doc.SelectNodes("descendant::*").Count;
Debug.WriteLine(string.Format("Added {0} nodes", countAfter - countBefore));
doc.Save(newFileName);
Debug.WriteLine("Wrote: " + newFileName);
我看到有{342}个节点添加到XmlDocument。