How to specify a parameter of an OperationContract as required

Question

I wonder how I can specify a parameter of an OperationContract method in WCF as required so that the generated xsd contains minOccurs="1" instead of minOccurs="0".

Example:

[ServiceContract(Namespace = "http://myUrl.com")]  
public interface IMyWebService  
{  
   [OperationContract]  
   string DoSomething(string param1, string param2, string param3);  
}

generates this xsd:

<xs:element name="DoSomething">  
  <xs:complexType>  
    <xs:sequence>  
      <xs:element minOccurs="0" name="param1" nillable="true" type="xs:string" />  
      <xs:element minOccurs="0" name="param2" nillable="true" type="xs:string" />  
      <xs:element minOccurs="0" name="param3" nillable="true" type="xs:string" />  
    </xs:sequence>  
  </xs:complexType>  

But I want to define minOccurs="1" within the code without the necessity to manually fix it in the xsd file.

Answer 1

You might need to wrap your parameters in a class, then you can use the DataMember attribute and specify IsRequired=true:

[ServiceContract(Namespace = "http://myUrl.com")]  
public interface IMyWebService  
{  
   [OperationContract]  
   string DoSomething(RequestMessage request);  
}

[DataContract]
public class RequestMessage
{
   [DataMember(IsRequired = true)]
   public string param1 { get; set; }

   [DataMember(IsRequired = true)]
   public string param3 { get; set; }

   [DataMember(IsRequired = true)]
   public string param3 { get; set; }
}

Answer 2

This implementation is nice to me: http://thorarin.net/blog/post/2010/08/08/Controlling-WSDL-minOccurs-with-WCF.aspx