删除序列化程序创建的空xmlns

Question

我有一个由"添加服务引用..."操作生成的对象,我手动使用我编写的通用序列化程序对其进行序列化.

我的问题是数据契约有一些内部对象.

序列化程序将空名称空间属性添加到内部对象的起始标记.有没有办法阻止这种情况发生？

Answer 1

如何使内部对象与根目录属于同一名称空间？这样,省略xmlns后代的声明是正确的.您可以使用该[assembly: ContractNamespace]属性覆盖程序集中所有合同的名称空间.有关示例,请参阅数据协定名称.

编辑:下面的一些例子详细说明.

假设您手动构建XML文档,并且不为任何元素指定命名空间.

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();

正如所料,生成的XML将没有名称空间声明:

<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,如果仅为根元素指定命名空间,则所有子元素必须使用声明显式地从该默认命名空间中恢复xml="".根据命名空间默认规则:

默认命名空间声明的范围从它出现的start-tag的开头延伸到相应的end-tag的末尾,不包括任何内部默认命名空间声明的范围.对于空标记,范围是标记本身.

因此,以下代码(具有为根元素指定的命名空间)...

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();

...将提供以下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>

注意<Publisher>元素的子元素如何不需要从根的命名空间中恢复,因为它们从父元素继承了"无命名空间"声明.

为了消除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();

这将为XML文档提供仅在根中声明的命名空间(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>

为了模仿涉及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,同时将其封装在Books具有显式命名空间的根元素中:

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,inner元素Book包含一个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,xmlns=""可以通过将Book元素的名称空间(及其后代的名称空间)设置为与根目录相对应来消除.对于XmlSerializer类,可以通过其构造函数的第二个参数指定所有元素的默认命名空间.(实际技术会根据您使用的序列化策略而有所不同.)

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();
}

这将产生预期的结果:

<?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>