具有不同本地名称的XDocument副本名称空间
本文关键字：副本 空间 XDocument | 更新日期: 2023-09-27 18:10:31
我有一个XML文档，看起来像这样:
<Schema Namespace="BBSF_Model" Alias="Self"
p1:UseStrongSpatialTypes="false"
xmlns:annotation="http://schemas.microsoft.com/ado/2009/02/edm/annotation"
xmlns:p1="http://schemas.microsoft.com/ado/2009/02/edm/annotation"
xmlns="http://schemas.microsoft.com/ado/2009/11/edm">
<EntityType Name="Customer">
<Property Name="Id" Type="Guid" Nullable="false" />
</EntityType>
</Schema>
我使用下面的代码来修改文档的Property元素:
XElement csdlEentity = csdlDoc.Root.Descendants()
.Where(d => d.Name.LocalName == "EntityType")
.FirstOrDefault(e => e.Attribute("Name").Value == "Customer");
var csdlProperty = csdlEentity.Descendants()
.Where(d => d.Name.LocalName == "Property")
.FirstOrDefault(e => e.Attribute("Name").Value == "Id");
XNamespace annotation = "http://schemas.microsoft.com/ado/2009/02/edm/annotation";
var attrib = new XAttribute(annotation + "StoreGeneratedPattern", "Computed");
csdlProperty.Add(attrib);
当我保存XDocument时，它的属性元素看起来像:
<Property Name="Id" Type="Guid" Nullable="false" p1:StoreGeneratedPattern="Computed" />
但是我想要的是:
<Property Name="Id" Type="Guid" Nullable="false" annotation:StoreGeneratedPattern="Computed" />
问题是xmlns "http://schemas.microsoft.com/ado/2009/02/edm/annotation"在文档的根节点中使用两个不同的别名/LocalNames (annotation, p1)引用了两次
xmlns:annotation="http://schemas.microsoft.com/ado/2009/02/edm/annotation"
xmlns:p1="http://schemas.microsoft.com/ado/2009/02/edm/annotation"
我不能更改或篡改根节点。
如何保存文档或更新Property元素以提供所需的输出?
理论上，使用前缀p1:StoreGeneratedPattern="Computed"还是annotation:StoreGeneratedPattern="Computed"应该无关紧要，因为它们表示与完全相同——一个扩展了XML名称{http://schemas.microsoft.com/ado/2009/02/edm/annotation}StoreGeneratedPattern的元素。如果您的接收XML解析器(或QA部门?)在处理此问题时遇到问题，最简单的解决方法可能是将解析器修改为符合标准。
话虽这么说，从XElement的参考源来看，事实证明，在写入时，名称空间/前缀属性对按照添加的顺序被推入下推堆栈，然后从堆栈的顶部到底部检查与元素名称空间的匹配—有效地以添加属性的相反顺序进行匹配。因此，如果希望使用前缀annotation，可以简单地对根元素中重复的名称空间的顺序进行排列。(详情请参阅此处)
但是，您写不能更改或篡改根节点。因此，您将被迫做一些工作:您将需要创建自己的XmlWriter的包装器子类并自己进行前缀重新映射。
首先，XmlWriter的一个非抽象子类，它包装了一个"真实的"XmlWriter:
public class XmlWriterProxy : XmlWriter
{
readonly XmlWriter baseWriter;
public XmlWriterProxy(XmlWriter baseWriter)
{
if (baseWriter == null)
throw new ArgumentNullException();
this.baseWriter = baseWriter;
}
protected virtual bool IsSuspended { get { return false; } }
public override void Close()
{
baseWriter.Close();
}
public override void Flush()
{
baseWriter.Flush();
}
public override string LookupPrefix(string ns)
{
return baseWriter.LookupPrefix(ns);
}
public override void WriteBase64(byte[] buffer, int index, int count)
{
if (IsSuspended)
return;
baseWriter.WriteBase64(buffer, index, count);
}
public override void WriteCData(string text)
{
if (IsSuspended)
return;
baseWriter.WriteCData(text);
}
public override void WriteCharEntity(char ch)
{
if (IsSuspended)
return;
baseWriter.WriteCharEntity(ch);
}
public override void WriteChars(char[] buffer, int index, int count)
{
if (IsSuspended)
return;
baseWriter.WriteChars(buffer, index, count);
}
public override void WriteComment(string text)
{
if (IsSuspended)
return;
baseWriter.WriteComment(text);
}
public override void WriteDocType(string name, string pubid, string sysid, string subset)
{
if (IsSuspended)
return;
baseWriter.WriteDocType(name, pubid, sysid, subset);
}
public override void WriteEndAttribute()
{
if (IsSuspended)
return;
baseWriter.WriteEndAttribute();
}
public override void WriteEndDocument()
{
if (IsSuspended)
return;
baseWriter.WriteEndDocument();
}
public override void WriteEndElement()
{
if (IsSuspended)
return;
baseWriter.WriteEndElement();
}
public override void WriteEntityRef(string name)
{
if (IsSuspended)
return;
baseWriter.WriteEntityRef(name);
}
public override void WriteFullEndElement()
{
if (IsSuspended)
return;
baseWriter.WriteFullEndElement();
}
public override void WriteProcessingInstruction(string name, string text)
{
if (IsSuspended)
return;
baseWriter.WriteProcessingInstruction(name, text);
}
public override void WriteRaw(string data)
{
if (IsSuspended)
return;
baseWriter.WriteRaw(data);
}
public override void WriteRaw(char[] buffer, int index, int count)
{
if (IsSuspended)
return;
baseWriter.WriteRaw(buffer, index, count);
}
public override void WriteStartAttribute(string prefix, string localName, string ns)
{
if (IsSuspended)
return;
baseWriter.WriteStartAttribute(prefix, localName, ns);
}
public override void WriteStartDocument(bool standalone)
{
baseWriter.WriteStartDocument(standalone);
}
public override void WriteStartDocument()
{
baseWriter.WriteStartDocument();
}
public override void WriteStartElement(string prefix, string localName, string ns)
{
if (IsSuspended)
return;
baseWriter.WriteStartElement(prefix, localName, ns);
}
public override WriteState WriteState
{
get { return baseWriter.WriteState; }
}
public override void WriteString(string text)
{
if (IsSuspended)
return;
baseWriter.WriteString(text);
}
public override void WriteSurrogateCharEntity(char lowChar, char highChar)
{
if (IsSuspended)
return;
baseWriter.WriteSurrogateCharEntity(lowChar, highChar);
}
public override void WriteWhitespace(string ws)
{
if (IsSuspended)
return;
baseWriter.WriteWhitespace(ws);
}
}
接下来，允许重新映射属性名称空间前缀的子类:
public class PrefixSelectingXmlWriterProxy : XmlWriterProxy
{
readonly Stack<XName> elements = new Stack<XName>();
readonly Func<string, string, string, Stack<XName>, string> attributePrefixMap;
public PrefixSelectingXmlWriterProxy(XmlWriter baseWriter, Func<string, string, string, Stack<XName>, string> attributePrefixMap)
: base(baseWriter)
{
if (attributePrefixMap == null)
throw new NullReferenceException();
this.attributePrefixMap = attributePrefixMap;
}
public override void WriteStartAttribute(string prefix, string localName, string ns)
{
prefix = attributePrefixMap(prefix, localName, ns, elements);
base.WriteStartAttribute(prefix, localName, ns);
}
public override void WriteStartElement(string prefix, string localName, string ns)
{
base.WriteStartElement(prefix, localName, ns);
elements.Push(XName.Get(localName, ns));
}
public override void WriteEndElement()
{
base.WriteEndElement();
elements.Pop(); // Pop after base.WriteEndElement() lets the base class throw an exception on a stack error.
}
}
最后你可以这样使用:
string xml;
using (var sw = new StringWriter())
{
using (var xmlWriter = XmlWriter.Create(sw, new XmlWriterSettings { Indent = true, IndentChars = " " }))
using (var xmlWriterProxy = new PrefixSelectingXmlWriterProxy(xmlWriter,
(string prefix, string localName, string ns, Stack<XName> parents) =>
{
if (localName == "StoreGeneratedPattern" && ns == annotation && parents.Peek() == XName.Get("Property", "http://schemas.microsoft.com/ado/2009/11/edm"))
return "annotation";
return prefix;
})
)
{
csdlDoc.WriteTo(xmlWriterProxy);
}
xml = sw.ToString();
}
Debug.WriteLine(xml);
正如您所看到的，这只是重新映射属性前缀，但它可以通过重写WriteStartElement(string prefix, string localName, string ns来扩展到重新映射元素前缀。
工作小提琴。
多亏了你的想法，我找到了一个解决方案。总体思路是，我将p1的值更改为添加新属性的任何内容，然后甚至在保存XDocument之前将p1返回到其原始值。
XAttribute p1 = csdlDoc.Root.Attributes()
.First(a => a.IsNamespaceDeclaration && a.Name.LocalName == "p1");
p1.Value = "http://schemas.microsoft.com/ado/2009/02/edm/annotation/TEMP";
......
// the same update now works as there is only one xmlns
XNamespace annotation = "http://schemas.microsoft.com/ado/2009/02/edm/annotation";
var attrib = new XAttribute(annotation + "StoreGeneratedPattern", "Computed");
csdlProperty.Add(attrib);
p1.Value = "http://schemas.microsoft.com/ado/2009/02/edm/annotation/";
另一个有效的解决方案是交换根节点声明的顺序(在注释之前声明p1)，如下所示:
<Schema Namespace="BBSF_Model" Alias="Self"
p1:UseStrongSpatialTypes="false"
xmlns:p1="http://schemas.microsoft.com/ado/2009/02/edm/annotation"
xmlns:annotation="http://schemas.microsoft.com/ado/2009/02/edm/annotation"
xmlns="http://schemas.microsoft.com/ado/2009/11/edm">