反序列化xml时忽略未知类型

Question

我有这个代码:

[XmlType( "Metadata" )]
[Serializable]
public class MetadataContainer : List<MetadataBase>
{
}

[XmlType( "Meta" )]
[XmlInclude( typeof( ReadonlyMetadata ) )]
[Serializable]
public abstract class MetadataBase
{
}

[XmlType( "Readonly" )]
[Serializable]
public class ReadonlyMetadata : MetadataBase
{
}

[TestFixture]
public class SerializationTests
{
    [Test]
    public void Can_deserialize_with_known_type()
    {
        const string text = @"<Metadata xmlns:xsd=""http://www.w3.org/2001/XMLSchema"" xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"">
                        <Meta xsi:type=""Readonly"" />
                    </Metadata>";

        var serializer = new XmlSerializer( typeof( MetadataContainer ) );
        var metas = (MetadataContainer)serializer.Deserialize( XmlReader.Create( new StringReader( text ) ) );

        Assert.That( metas.Count, Is.EqualTo( 1 ) );
        Assert.That( metas.First(), Is.InstanceOf<ReadonlyMetadata>() );
    }

    [Test]
    public void Can_deserialize_with_unknown_type()
    {
        const string text = @"<Metadata xmlns:xsd=""http://www.w3.org/2001/XMLSchema"" xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"">
                        <Meta xsi:type=""Hello"" />
                    </Metadata>";

        var serializer = new XmlSerializer( typeof( MetadataContainer ) );
        var metas = (MetadataContainer)serializer.Deserialize( XmlReader.Create( new StringReader( text ) ) );

        Assert.That( metas.Count, Is.EqualTo( 0 ) );
    }
}

第一个测试工作,但当我运行第二个测试时,我收到此错误:

System.InvalidOperationException:XML文档中存在错误(2,9).----> System.InvalidOperationException:无法识别指定的类型:name ='Hello',namespace ='',at.

我没有得到这个错误,而是希望忽略不识别的类型.有没有办法做到这一点？

Answer 1

类似问题的通用解决方案：

看一下未知元素事件（链接）和未知属性事件（链接），看看它们是否解决了问题，否则我们就得搞砸了。继续阅读...

这个问题的工作解决方案

请记住，我不知道您的任务是什么，据我所知，它将 xml 序列化到您的数据结构中。如果您可以更改数据结构，我建议您查看 Linq2XML 并根据您的目的创建一个智能工厂。

[TestMethod]
public void TestLinq2Xml()
{
  const string text = @"<Metadata xmlns:xsd=""http://www.w3.org/2001/XMLSchema"" xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"">
                            <Meta xsi:type=""Readonly"" />
                            <Meta xsi:type=""Garbage"" />
                      </Metadata>";

  // Get the "names" of all implementors of MetadataBase
  var types = AppDomain.CurrentDomain.GetAssemblies().ToList()
     .SelectMany(s => s.GetTypes())
         .Where(p => typeof(MetadataBase).IsAssignableFrom(p) && !p.IsAbstract && !p.IsInterface)
         .Where(t => t.GetCustomAttributes(typeof(XmlTypeAttribute), false).Any())
         .Select(t => t.GetCustomAttributes(typeof(XmlTypeAttribute), false)
             .Cast<XmlTypeAttribute>().First().TypeName);

  // Create a parser
  var parser = new XmlSerializer(typeof(MetadataBase));

  // Create metadatacontainer to fill
  var metas = new MetadataContainer();
  // Fill it with matching from from the XML
  metas.AddRange((from t in XDocument.Parse(text).Descendants("Meta")
                where types.Contains(t.Attribute(XName.Get("type", "http://www.w3.org/2001/XMLSchema-instance")).Value)
                select (MetadataBase)parser.Deserialize(t.CreateReader())).ToList());

  // Should be one guy present
  Assert.AreEqual(metas.Count, 1);
}