how can i serialize this class?
public class MyClass {
IInterface MyProperty { get; set;}
}
You need to add a setter to MyProperty as Xml serialization rules mandate that serialization must be able to round-trip i.e. it must be able to get the property for serialization, then set the property for deserialization.
As chibacity said, you need to add a setter to the property. You also need to add the XmlInclude attribute to the property to specify the possible implementing types, otherwise the XmlSerializer won't know what type to instantiate when deserializing
The XmlSerializer cannot serialize interfaces.
If you know the concrete types you will be dealing with in advance then you can use the XmlInclude approach. If not then there have been a few discussions about how to handle this:
XML serialization of interface
property
XmlSerialization with Interfaces
Serializing without XmlInclude
Make the class that implements IInterface Serializable like you normally would and it will all work.
Related
Every time I meet this attribute, I always see such usage:
[DataContract]
class DataTransferObject
{
[DataMember]
public int Value {get;set;}
}
And in this example all inherited members should apply DataMember attribute to every property or field, this can lead to VERY clumsy and poilerplate code. But, recently I found (maybe secret feature?) a very elegant way of using it:
[DataContract]
public abstract class DTOBase
{
}
public class MyDTO : DTOBase
{
public int Value {get;set;}
public MyDTO(){} //important part is here
}
Important part: You should always explicitly define parameterless constructor, otherwise it won't serialize properly.
And yeah. It will serialize all its public members, no matter how deep will be inheritance, without need to apply attributes to members or class definitions.
Is this somehow documented somewhere (I didn't found)? Because, I were very supprized how much of boilerplate can be avoided.
Actually, you don't need to use DataContract and DataMember attributes if you don't want to, however they give you flexibility in defining what needs to be serialized and how.
I suggest starting with article Serializable Types on MSDN, it has a lot of information how Data Contract serializer works. Here are first 2 paragraphs, proving that you don't need to use attributes:
By default, the DataContractSerializer serializes all publicly visible
types.
All public read/write properties and fields of the type are
serialized. You can change the default behavior by applying the
DataContractAttribute and DataMemberAttribute attributes to the types
and members This feature can be useful in situations in which you have
types that are not under your control and cannot be modified to add
attributes. The DataContractSerializer recognizes such "unmarked"
types.
The main rules that apply to your case are:
DataContract attribute is not inherited. You can either apply it or not on your base class DTOBase, it is ignored in child class MyDTO. You can remove DataContract attribute from DTOBase class and result will be the same.
If you use DataContract attribute on a class, then only members that have DataMember attribute will be serialized. This is what happened in class DataTransferObject in your first sample.
If you do not use DataContract attribute on a class, then all public members of a class are serialized. This is what happened with your class MyDTO.
I find the [DataContract] and [DataMember] attributes a bit messy and would rather do this with code in a config method or something. Is this possible?
You don't have to use these attributes at all. DataContractSerializer will serialize all public properties with getter and setter but in case of serializing entities with navigation properties you will easily end with exception due to "cyclic reference".
To avoid that exception you must either use [DataContract(IsReference = true)] on your entity class with DataMember on every property you want to serilize or IgnoreDataMember on every property you don't want to serialize.
The last and the most complex option is avoiding attributes completely and custom classes implementing IDataContractSurrogate to control serialization outside of the type.
You can also write your completely custom serialization process or use XML serialization or binary serialization with all its requirements.
No, the DataContractSerializer is an opt-in serializer - you have to tell it what you want included.
With other serializers you need to use things like NonSerializedAttribute or XmlIgnoreAttribute to tell the serializer to leave things alone.
I know this is a rather old post, but I came here thinking the same thing if there is a way to set all member attributes automatically on some legacy code with public fields and no getters and setters.
What makes it look just a little bit less messy is shortening up the name DataMember:
using DM = System.Runtime.Serialization.DataMemberAttribute;
[DataContract]
public class SomeClass
{
[DM] public bool IsMO;
[DM] public string LabCode;
[DM] public string OrderNumber;
}
When serializing a class I get an error if the XmlIgnore attribute is commented. When I uncomment the XmlIgnore attribute it works fine. Can anyone tell me why a property can't be serializable?
Normally, it will tell you why very clearly in the exception - look in particular at the InnerException; however, to summarise:
For a custom type SomeType to be serializable via XmlSerializer (either as the root object or via a property, i.e. public SomeType MemberName {get;set;})
it must be public
it must have a public parameterless constructor
a few generic combinations may not be supported
it must be expected (exposing data as object is a no-go, for example; subtypes of SomeType must be advertised in advance, typically via [XmlInclude(...)])
it must be concrete (non-abstract), or have concrete implementations defined via [XmlInclude(...)]
Using [XmlIgnore] removes the type from consideration, so types that are not xml-friendly can be avoided. You can also try IXmlSerializable for those cases
I'm currently using an XMLSerializer to serialize a list of a class of my own. One of the class's properties is an instance of a sealed class that does not have a parameterless constructor, so the XML Serializer refuses to serialize the class. How can I get around this? I need that property to be serialized.
Is there some way for me to specify how that class should be serialized?
We'd like to stay with XML; is there another XML serializer that I could use that would not have this problem?
Again, I apologize if this is a dupe, but I had no idea what to search.
[EDIT] To clarify, I don't have access to the source of the sealed class.
It's not possible to do directly; XmlSerializer can't cope with classes that don't have a parameterless constructor.
What I normally do is wrap the parameterless class in another class that's compatible with XML. The wrapper class has a parameterless constructor and a set of read-write properties; it has a FromXml method that calls the real class's constructor.
[XmlIgnore]
public SomeClass SomeProperty { get; set; }
[XmlElement("SomeProperty")]
public XmlSomeClass XmlSomeProperty
{
get { return XmlSomeClass.ToXml(SomeProperty); }
set { SomeProperty = value.FromXml(); }
}
Can you make a private parameterless constructor? That will work assuming you have access to the class's code.
You can implement ISerializable on the containing class, then implement a custom serializer.
Depending on the complexity of the xml, you might have some luck with DataContractSerializer. This doesn't offer anything like the same level of xml control, but it bypasses the constructor completely. And works for private types.
I might also ask: does it actually need to be xml? There are other serializers for things like json or protobuf that don't have the XmlSerializer limitations.
Use IXmlSerializable, XmlSerializer is too limited.
I am building a class and in the interface for my class(es) I have a property declared
object MyObject { get; set; }
What I want to do is force whatever is stored in MyObject to be serializable. Is there a good way to do this?
Normally, I'd use where : ISerializable, but for serialization you use an attribute, not inheritance, or at least that is my assumption.
I never could figure out how to enforce a class be Serializable. I had to move away from generic classes anyway for other reasons, so through inheritance I just create a property for my object to be serialized and serialize/deserialize it in the set/get accessors and store the serialized string in a string property in the base class, which is inherited.