How to generate XML Schema from C# type with XSD.exe such that [XmlAttribute] property is mapped to required XML attribute?

Question

Put it simply, when I use XSD.exe (that comes with Visual Studio 2012) to generate XML schema file from this class:

[Serializable]
public class Person
{
    [XmlAttribute]
    public string Name { get; set; }

    [XmlAttribute]
    public int Age { get; set; }
}

I get this as the result:

<?xml version="1.0" encoding="utf-8"?>
<xs:schema elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:element name="Person" nillable="true" type="Person" />
  <xs:complexType name="Person">
    <xs:attribute name="Name" type="xs:string" />
    <xs:attribute name="Age" type="xs:int" use="required" />
  </xs:complexType>
</xs:schema>

Notice that Age attribute is specified as required (it has use="required" ) in generated schema while attribute Name is not.

I use XSD.exe like this:

xsd.exe Sample.exe /type:Person

Where Sample.exe is .NET assembly where Person class is defined.

I would like to somehow specify in my class which XmlAttribute properties are required and which are not so that XSD.exe can automatically generate schema from that. Is this possible?

Answer 1

Unless there's a bug in XSD (it is not clear if you tried what it is described in the XSD.exe documentation, specifically the attribute element binding support - right now I can't test it), the answer is yes, you can.

In your case, the different behaviour between Name and Age is simply due to the fact that a String field is nullable, whereas the int one is not (somehow I don't believe an int? will make a difference in your case, still you can try it...) Attributes are not nillable (from an XSD perspective), therefore the use of optional.

Use Attribute: Generating an XML Schema document from classes

In either of the following two cases, Xsd.exe does not specify the use attribute, reverting to the default value optional:

• An extra public bool field that follows the Specified naming convention is present.

• A default value is assigned to the member via an attribute of type System.Component.DefaultValueAttribute.

If neither of these conditions is met, Xsd.exe produces a value of required for the use attribute.