I am using XmlSerializer to write and read an object to xml in C#. I currently use the attributes XmlElement
and XmlIgnore
to manipulate the serialization of the object.
If my xml file is missing an xml element that I require, my object still deserializes (xml -> object) just fine. How do I indicate (preferably via Attributes) that a certain field is "required"?
Here is a sample method of what I am using currently:
[XmlElement(ElementName="numberOfWidgets")]
public int NumberThatIsRequired {
set ...;
get ...;
}
My ideal solution would be to add something like an XmlRequired
attribute.
Also, is there a good reference for what Attributes are available to manipulate the behavior of XmlSerializer?
Yes, you can tell the XmlSerializer to ignore namespaces during de-serialization.
Since XmlSerializer is one of the few thread safe classes in the framework you really only need a single instance of each serializer even in a multithreaded application. The only thing left for you to do, is to devise a way to always retrieve the same instance.
XmlSerializer enables you to control how objects are encoded into XML. The XmlSerializer enables you to control how objects are encoded into XML, it has a number of constructors.
The XmlSerializer creates C# (. cs) files and compiles them into . dll files in the directory named by the TEMP environment variable; serialization occurs with those DLLs. These serialization assemblies can be generated in advance and signed by using the SGen.exe tool.
Serialization is a process by which an object's state is transformed in some serial data format, such as XML or binary format. Deserialization, on the other hand, is used to convert the byte of data, such as XML or binary data, to object type.
The only way I've found to do this is via XSD. What you can do is validate while you deserialize:
static T Deserialize<T>(string xml, XmlSchemaSet schemas)
{
//List<XmlSchemaException> exceptions = new List<XmlSchemaException>();
ValidationEventHandler validationHandler = (s, e) =>
{
//you could alternatively catch all the exceptions
//exceptions.Add(e.Exception);
throw e.Exception;
};
XmlReaderSettings settings = new XmlReaderSettings();
settings.Schemas.Add(schemas);
settings.ValidationType = ValidationType.Schema;
settings.ValidationEventHandler += validationHandler;
XmlSerializer serializer = new XmlSerializer(typeof(T));
using (StringReader sr = new StringReader(xml))
using (XmlReader books = XmlReader.Create(sr, settings))
return (T)serializer.Deserialize(books);
}
I've got an answer for the second part: "Attributes that control XML serialization".
Still investigating the first part...
EDIT: I strongly suspect you can't do this through XML deserialization itself. I've just run xsd.exe on a sample schema which includes a required attribute - and it's exactly the same if the attribute is marked as being optional. If there were a way of requiring properties to be set, I'd expect it to be implemented in that case.
I suspect you've basically got to just validate your tree of objects after deserializing it. Sorry about that...
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