c# – 属性上的XElement默认命名空间提供了意外行为

我在创建包含默认命名空间和命名命名空间的 XML文档时遇到问题,很难解释更容易显示我想要生成的内容…

<Root xmlns="http://www.adventure-works.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:SchemaLocation="http://www.SomeLocatation.Com/MySchemaDoc.xsd">
  <Book title="Enders Game" author="Orson Scott Card" />
  <Book title="I Robot" author="Isaac Asimov" />
</Root>

但我最终得到的是……

<Root xmlns="http://www.adventure-works.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:SchemaLocation="http://www.SomeLocatation.Com/MySchemaDoc.xsd">
  <Book p3:title="Enders Game" p3:author="Orson Scott Card" xmlns:p3="http://www.adventure-works.com" />
  <Book p3:title="I Robot" p3:author="Isaac Asimov" xmlns:p3="http://www.adventure-works.com" />
</Root>

我编写的用于生成此XML代码段的代码是……

XNamespace aw = "http://www.adventure-works.com";
  XNamespace xsi = "http://www.w3.org/2001/XMLSchema-instance";
  XElement root = new XElement(aw + "Root",
      new XAttribute("xmlns", "http://www.adventure-works.com"),
      new XAttribute(XNamespace.Xmlns + "xsi", "http://www.w3.org/2001/XMLSchema-instance"),
      new XAttribute(xsi + "SchemaLocation", "http://www.SomeLocatation.Com/MySchemaDoc.xsd"),

      new XElement(aw + "Book",
        new XAttribute(aw + "title", "Enders Game"),
        new XAttribute(aw + "author", "Orson Scott Card")),
      new XElement(aw + "Book",
        new XAttribute(aw + "title", "I Robot"),
        new XAttribute(aw + "author", "Isaac Asimov")));

基于example on MSDN

****编辑****

好的,通过一些更多的实验,我现在对XML名称空间如何工作非常困惑….

如果我删除了aw属性我得到了我以后的东西……但现在看来我所追求的并不是我所期望的.我认为名称空间是从父母那里继承而来的,属性也不是这样吗？因为,这个读取属性的代码不能像我预期的那样工作……

XElement xe = XElement.Parse(textBox1.Text);
  XNamespace aw = "http://www.adventure-works.com";
  var qry = from x in xe.Descendants(aw + "Book")
            select (string)x.Attribute(aw + "author");

但是,如果我删除属性上的aw就可以了,这导致我假设我在默认命名空间中没有属性.它是否正确？

好问题.我挖了一下,找到了 this bit of the XML spec：

A default namespace declaration
applies to all unprefixed element
names within its scope. Default
namespace declarations do not apply
directly to attribute names; the
interpretation of unprefixed
attributes is determined by the
element on which they appear.

它后来继续给出这个例子：

For example, each of the bad empty-element tags is illegal in the following:

<!-- http://www.w3.org is bound to n1 and n2 -->
<x xmlns:n1="http://www.w3.org" 
   xmlns:n2="http://www.w3.org" >
  <bad a="1"     a="2" />
  <bad n1:a="1"  n2:a="2" />
</x>

However, each of the following is legal, the second because the default namespace does not > apply to attribute names:

<!-- http://www.w3.org is bound to n1 and is the default -->
<x xmlns:n1="http://www.w3.org" 
   xmlns="http://www.w3.org" >
  <good a="1"     b="2" />
  <good a="1"     n1:a="2" />
</x>

所以基本上,默认情况下属性名称看起来没有命名空间,这解释了你所看到的一切:)