[英]c# inheriting generic collection and serialization
The setup:设置:
class Item
{
private int _value;
public Item()
{
_value = 0;
}
public int Value { get { return _value; } set { _value = value; } }
}
class ItemCollection : Collection<Item>
{
private string _name;
public ItemCollection()
{
_name = string.Empty;
}
public string Name { get {return _name;} set {_name = value;} }
}
Now, trying to serialize using the following code fragment:现在,尝试使用以下代码片段进行序列化:
ItemCollection items = new ItemCollection();
...
XmlSerializer serializer = new XmlSerializer(typeof(ItemCollection));
using (FileStream f = File.Create(fileName))
serializer.Serialize(f, items);
Upon looking at the resulting XML I see that the ItemCollection.Name value is not there!在查看生成的 XML 后,我看到 ItemCollection.Name 值不存在!
I think what may be happening is that the serializer sees the ItemCollection type as a simple Collection thus ignoring any other added properties...我认为可能发生的事情是序列化程序将 ItemCollection 类型视为一个简单的集合,因此忽略了任何其他添加的属性......
Is there anyone having encountered such a problem and found a solution?有没有人遇到过这样的问题并找到了解决方案?
Regards,问候,
Stécy斯泰西
This behavior is "By Design".此行为是设计使然”。 When deriving from a collection class the Xml Seralizier will only serialize the collection elements.从集合 class 派生时,Xml Seralizier 将仅序列化集合元素。 To work around this you should create a class that encapsulates the collection and the name and have that serialized.要解决此问题,您应该创建一个 class 封装集合和名称并将其序列化。
class Wrapper
{
private Collection<Item> _items;
private string _name;
public Collection<Item> Items { get {return _items; } set { _items = value; } }
public string Name { get { return _name; } set { _name = value; } }
}
A detailed discussion is available here: http://blogs.vertigo.com/personal/chris/Blog/archive/2008/02/01/xml-serializing-a-derived-collection.aspx此处提供详细讨论: http://blogs.vertigo.com/personal/chris/Blog/archive/2008/02/01/xml-serializing-a-derived-collection.aspx
XmlSerializer is evil. XmlSerializer 是邪恶的。 That said, any object that implements IEnumerable will be serialized as an simple collection, ignoring any extra properties you've added yourself.也就是说,任何实现 IEnumerable 的 object 都将被序列化为一个简单的集合,而忽略您自己添加的任何额外属性。
You will need to create a new class that holds both your property and a property that returns the collection.您将需要创建一个新的 class 来保存您的属性和返回集合的属性。
I am not sure if I am missing something, but do you want the resulting xml to be我不确定我是否遗漏了什么,但是您是否希望生成的 xml
<ItemCollection>
<Name>name val</Name>
<Item>
<Value>1</alue>
</Item
<Item>
<Value>2</alue>
</Item
</ItemCollection>
If so, just apply the XmlRoot attribute to the itemcollection class and set the element name...如果是这样,只需将 XmlRoot 属性应用于 itemcollection class 并设置元素名称...
[XmlRoot(ElementName="ItemCollection")]
public class ItemCollection : Collection<Item>
{
[XmlElement(ElementName="Name")]
public string Name {get;set;}
}
This will instruct the serializer to output the required name for you collection container.这将指示序列化程序到 output 收集容器所需的名称。
public class Animals : List<Animal>, IXmlSerializable
{
private static Type[] _animalTypes;//for IXmlSerializable
public Animals()
{
_animalTypes = GetAnimalTypes().ToArray();//for IXmlSerializable
}
// this static make you access to the same Animals instance in any other class.
private static Animals _animals = new Animals();
public static Animals animals
{
get {return _animals; }
set { _animals = value; }
}
#region IXmlSerializable Members
public System.Xml.Schema.XmlSchema GetSchema()
{
return null;
}
public void ReadXml(System.Xml.XmlReader reader)
{
bool wasEmpty = reader.IsEmptyElement;
reader.Read();
if (wasEmpty)
return;
reader.MoveToContent();
reader.ReadStartElement("Animals");
// you MUST deserialize with 'List<Animal>', if Animals class has no 'List<Animal>' fields but has been derived from 'List<Animal>'.
List<Animal> coll = GenericSerializer.Deserialize<List<Animal>>(reader, _animalTypes);
// And then, You can set 'Animals' to 'List<Animal>'.
_animals.AddRange(coll);
reader.ReadEndElement();
//Read Closing Element
reader.ReadEndElement();
}
public void WriteXml(System.Xml.XmlWriter writer)
{
writer.WriteStartElement("Animals");
// You change 'List<Animal>' to 'Animals' at first.
List<Animal> coll = new List<Animal>(_animals);
// And then, You can serialize 'Animals' with 'List<Animal>'.
GenericSerializer.Serialize<List<Animal>>(coll, writer, _animalTypes);
writer.WriteEndElement();
}
#endregion
public static List<Type> GetAnimalTypes()
{
List<Type> types = new List<Type>();
Assembly asm = typeof(Animals).Assembly;
Type tAnimal = typeof(Animal);
//Query our types. We could also load any other assemblies and
//query them for any types that inherit from Animal
foreach (Type currType in asm.GetTypes())
{
if (!currType.IsAbstract
&& !currType.IsInterface
&& tAnimal.IsAssignableFrom(currType))
types.Add(currType);
}
return types;
}
}
You can also try to implelemnt your own serialization using IXmlSerializable interface您还可以尝试使用 IXmlSerializable 接口实现自己的序列化
public class ItemCollection : Collection<Item>,IXmlSerializable
{
private string _name;
public ItemCollection()
{
_name = string.Empty;
}
public string Name
{
get { return _name; }
set { _name = value; }
}
#region IXmlSerializable Members
public System.Xml.Schema.XmlSchema GetSchema()
{
return null;
}
public void ReadXml(System.Xml.XmlReader reader)
{
}
public void WriteXml(System.Xml.XmlWriter writer)
{
writer.WriteElementString("name", _name);
List<Item> coll = new List<Item>(this.Items);
XmlSerializer serializer = new XmlSerializer(coll.GetType());
serializer.Serialize(writer, coll);
}
#endregion
}
Above code will generate the serialized xml as上面的代码将生成序列化的 xml 为
<?xml version="1.0"?>
<ItemCollection>
<name />
<ArrayOfItem xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<Item>
<Value>1</Value>
</Item>
<Item>
<Value>2</Value>
</Item>
</ArrayOfItem>
</ItemCollection>
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