Question

I’ve recently been trying to generate data contracts from xsd files, using svcutil like this:

svcutil.exe /t:code /dconly /out:MyContract.cs /n:*,My.Namespace MyDataDefinition.xsd

The XSD mostly consists of definitions like this:

<xsd:complexType name="SomeComplexObjectType">
    <xsd:sequence>
        <xsd:element name="FirstData" type="xsd:string" minOccurs="0" />
        <xsd:element name="SecondData" type="xsd:string" minOccurs="0" />
    </xsd:sequence>
</xsd:complexType>

svcutil generates something like this:

[System.Diagnostics.DebuggerStepThroughAttribute()]
[System.CodeDom.Compiler.GeneratedCodeAttribute("System.Runtime.Serialization", "3.0.0.0")]
[System.Runtime.Serialization.DataContractAttribute(Name="SomeComplexObjectType")]
public partial class PersonInfo : object, System.Runtime.Serialization.IExtensibleDataObject
{
    private string FirstDataField;
    private string SecondDataField;

    [System.Runtime.Serialization.DataMemberAttribute(EmitDefaultValue=false)]
    public string FirstData
    {
        get
        {
            return this.FirstDataField;
        }
        set
        {
            this.FirstDataField= value;
        }
    }

    [System.Runtime.Serialization.DataMemberAttribute(EmitDefaultValue=false)]
    public string SecondData
    {
        get
        {
            return this.SecondDataField;
        }
        set
        {
            this.SecondDataField= value;
        }
    }
}

Which works fine, however, the “EmitDefaultValue=false” attributes are not necessary. Not to mention that it introduces a lot of noise into the wsdl, adding stuff like this:

<xsd:element minOccurs="0" name="FirstData" nillable="true" type="xsd:string">
    <xsd:annotation>
        <xsd:appinfo>
            <DefaultValue xmlns="http://schemas.microsoft.com/2003/10/Serialization/" EmitDefaultValue="false"/>
        </xsd:appinfo>
    </xsd:annotation>
</xsd:element>

Currently I’m just hand-editing the generated contract, but that is not ideal from a maintenance standpoint.

Does anyone know how to prevent svcutil from automatically generating these EmitDefaultValue=false attributes?

Answer 1

Please see this article.

On schema import, the EmitDefaultValue property is automatically set
to false whenever the WCF-specific annotation mentioned previously is
detected. It is also set to false for reference types that have the
nillable property set to false to support specific interoperability
scenarios that commonly occur when consuming ASP.NET Web services

It appears your only choice is to modify the incoming schema so the relevant elements are nillable.