我有一个由“添加服务引用...”操作生成的对象，我正在使用我编写的通用序列化程序手动序列化它。

我的问题是数据协定有一些内部对象。

序列化程序将一个空的命名空间属性添加到内部对象的起始标记中。有什么办法可以阻止这种情况发生吗？

最佳答案

如何使您的内部对象与根属于同一个命名空间？这样，省略 xmlns 是正确的后代的声明。您可以使用 [assembly: ContractNamespace]属性以覆盖程序集中所有契约(Contract)的命名空间。引用Data Contract Names举个例子。

编辑:下面是一些示例的详细说明。

假设您正在手动构建一个 XML 文档，并且没有为您的任何元素指定 namespace 。

XDocument xmlDocument = new XDocument(
    new XElement("Book",
        new XElement("Title", "Animal Farm"),
        new XElement("Author", "George Orwell"),
        new XElement("Publisher",
            new XElement("Name", "Secker and Warburg"),
            new XElement("Location", "London"),
            new XElement("Founded", 1910))));
return xmlDocument.ToString();

如预期的那样，生成的 XML 没有命名空间声明:

<Book>
  <Title>Animal Farm</Title>
  <Author>George Orwell</Author>
  <Publisher>
    <Name>Secker and Warburg</Name>
    <Location>London</Location>
    <Founded>1910</Founded>
  </Publisher>
</Book>

但是，如果您仅为根元素指定一个命名空间，则所有子元素都必须使用 xml="" 显式恢复到该默认命名空间之外。声明。根据 Namespace Defaulting规则:

The scope of a default namespace declaration extends from the beginning of the start-tag in which it appears to the end of the corresponding end-tag, excluding the scope of any inner default namespace declarations. In the case of an empty tag, the scope is the tag itself.

因此，以下代码(具有为根元素指定的 namespace )...

XDocument xmlDocument = new XDocument(
    new XElement("{http://example.com/library}Book",
        new XElement("Title", "Animal Farm"),
        new XElement("Author", "George Orwell"),
        new XElement("Publisher",
            new XElement("Name", "Secker and Warburg"),
            new XElement("Location", "London"),
            new XElement("Founded", 1910))));
return xmlDocument.ToString();

...将给出以下 XML:

<Book xmlns="http://example.com/library">
  <Title xmlns="">Animal Farm</Title>
  <Author xmlns="">George Orwell</Author>
  <Publisher xmlns="">
    <Name>Secker and Warburg</Name>
    <Location>London</Location>
    <Founded>1910</Founded>
  </Publisher>
</Book>

请注意 <Publisher> 的 child 是如何元素不需要从根的命名空间中恢复，因为它们从父级继承了“无命名空间”声明。

消除xmlns=""声明，为了演示，我们可以为所有后代分配相同的命名空间:

XDocument xmlDocument = new XDocument(
    new XElement("{http://example.com/library}Book",
        new XElement("{http://example.com/library}Title", "Animal Farm"),
        new XElement("{http://example.com/library}Author", "George Orwell"),
        new XElement("{http://example.com/library}Publisher",
            new XElement("{http://example.com/library}Name", "Secker and Warburg"),
            new XElement("{http://example.com/library}Location", "London"),
            new XElement("{http://example.com/library}Founded", 1910))));
return xmlDocument.ToString();

这将给出一个 XML 文档，其 namespace 仅在根中声明(并在所有后代中隐式继承):

<Book xmlns="http://example.com/library">
  <Title>Animal Farm</Title>
  <Author>George Orwell</Author>
  <Publisher>
    <Name>Secker and Warburg</Name>
    <Location>London</Location>
    <Founded>1910</Founded>
  </Publisher>
</Book>

要模拟涉及 Web 服务的场景，我们可以创建以下 WCF 服务。

[DataContract]
public class Book
{
    [DataMember]
    public string Title { get; set; }
    [DataMember]
    public string Author { get; set; }
    [DataMember]
    public Publisher Publisher { get; set; }
}

[DataContract]
public class Publisher
{
    [DataMember]
    public string Name { get; set; }
    [DataMember]
    public string Location { get; set; }
    [DataMember]
    public short Founded { get; set; }
}

[ServiceContract]
public interface ILibraryService
{
    [OperationContract]
    Book GetBook();
}

public class LibraryService : ILibraryService
{
    public Book GetBook()
    {
        return new Book
        {
            Title = "Animal Farm",
            Author = "George Orwell",
            Publisher = new Publisher
            {
                Name = "Secker and Warburg",
                Location = "London",
                Founded = 1910,
            }
        };
    }
}

我们在客户端应用程序中添加对上述服务的服务引用，使用它的操作，并将结果序列化，同时将其包含在根中 Books具有显式命名空间的元素:

using (var libraryClient = new LibraryServiceReference.LibraryServiceClient())
{
    var book = libraryClient.GetBook();

    var stringBuilder = new StringBuilder();
    using (XmlWriter xmlWriter = XmlWriter.Create(stringBuilder))
    {
        xmlWriter.WriteStartElement("Books", "http://example.com/library");
        var serializer = new XmlSerializer(book.GetType());
        serializer.Serialize(xmlWriter, book);
        xmlWriter.WriteEndElement();
    }

    return stringBuilder.ToString();
}

在这种情况下，内部元素 Book包含 xmlns=""声明。

<?xml version="1.0" encoding="utf-16"?>
<Books xmlns="http://example.com/library">
  <Book xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
        xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
        xmlns="">
    <ExtensionData />
    <Author>George Orwell</Author>
    <Publisher>
      <ExtensionData />
      <Founded>1910</Founded>
      <Location>London</Location>
      <Name>Secker and Warburg</Name>
    </Publisher>
    <Title>Animal Farm</Title>
  </Book>
</Books>

如上所述，这个 xmlns=""可以通过设置 Book 来消除元素的命名空间(及其后代的命名空间)对应于根的命名空间。对于 XmlSerializer类，所有元素的默认命名空间可以通过其构造函数的第二个参数指定。 (实际技术会因您使用的序列化策略而异。)

using (var libraryClient = new LibraryServiceReference.LibraryServiceClient())
{
    var book = libraryClient.GetBook();

    var stringBuilder = new StringBuilder();
    using (XmlWriter xmlWriter = XmlWriter.Create(stringBuilder))
    {
        xmlWriter.WriteStartElement("Books", "http://example.com/library");
        var serializer = new XmlSerializer(book.GetType(), "http://example.com/library");
        serializer.Serialize(xmlWriter, book);
        xmlWriter.WriteEndElement();
    }

    return stringBuilder.ToString();
}

这将给出预期的结果:

<?xml version="1.0" encoding="utf-16"?>
<Books xmlns="http://example.com/library">
  <Book xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
        xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <ExtensionData />
    <Author>George Orwell</Author>
    <Publisher>
      <ExtensionData />
      <Founded>1910</Founded>
      <Location>London</Location>
      <Name>Secker and Warburg</Name>
    </Publisher>
    <Title>Animal Farm</Title>
  </Book>
</Books>

关于c# - 删除序列化程序创建的空 xmlns，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/8822859/