WCF service proxy not setting "FieldSpecified" property

Question

I've got a WCF DataContract that looks like the following:

namespace MyCompanyName.Services.Wcf
{
  [DataContract(Namespace = "http://mycompanyname/services/wcf")]
  [Serializable]
  public class DataContractBase
  {
    [DataMember]
    public DateTime EditDate { get; set; }

    // code omitted for brevity...
  }
}

When I add a reference to this service in Visual Studio, this proxy code is generated:

/// <remarks/>
[System.CodeDom.Compiler.GeneratedCodeAttribute("System.Xml", "2.0.50727.3082")]
[System.SerializableAttribute()]
[System.Diagnostics.DebuggerStepThroughAttribute()]
[System.ComponentModel.DesignerCategoryAttribute("code")]
[System.Xml.Serialization.XmlTypeAttribute(Namespace="http://mycompanyname/services/wcf")]
public partial class DataContractBase : object, System.ComponentModel.INotifyPropertyChanged {

    private System.DateTime editDateField;

    private bool editDateFieldSpecified;

    /// <remarks/>
    [System.Xml.Serialization.XmlElementAttribute(Order=0)]
    public System.DateTime EditDate {
        get {
            return this.editDateField;
        }
        set {
            this.editDateField = value;
            this.RaisePropertyChanged("EditDate");
        }
    }

    /// <remarks/>
    [System.Xml.Serialization.XmlIgnoreAttribute()]
    public bool EditDateSpecified {
        get {
            return this.editDateFieldSpecified;
        }
        set {
            this.editDateFieldSpecified = value;
            this.RaisePropertyChanged("EditDateSpecified");
        }
    }

    // code omitted for brevity...
}

As you can see, besides generating a backing property for EditDate, an additional <propertyname>Specified property is generated. All good, except that when I do the following:

DataContractBase myDataContract = new DataContractBase();
myDataContract.EditDate = DateTime.Now;

new MyServiceClient.Update(new UpdateRequest(myDataContract));

the EditDate was not getting picked up by the endpoint of the service (does not appear in the transmitted XML).

I debugged the code and found that, although I was setting EditDate, the EditDateSpecified property wasn't being set to true as I would expect; hence, the XML serializer was ignoring the value of EditDate, even though it's set to a valid value.

As a quick hack I modified the EditDate property to look like the following:

   /// <remarks/>
    [System.Xml.Serialization.XmlElementAttribute(Order=0)]
    public System.DateTime EditDate {
        get {
            return this.editDateField;
        }
        set {
            this.editDateField = value;

            // hackhackhack
            if (value != default(System.DateTime))
            {
              this.EditDateSpecified = true;
            }
            // end hackhackhack

            this.RaisePropertyChanged("EditDate");
        }
    }

Now the code works as expected, but of course every time I re-generate the proxy, my modifications are lost. I could change the calling code to the following:

DataContractBase myDataContract = new DataContractBase();
myDataContract.EditDate = DateTime.Now;
myDataContract.EditDateSpecified = true;

new MyServiceClient.Update(new UpdateRequest(myDataContract));

but that also seems like a hack-ish waste of time.

So finally, my question: does anyone have a suggestion on how to get past this unintuitive (and IMO broken) behavior of the Visual Studio service proxy generator, or am I simply missing something?

Answer 1

It might be a bit unintuitive (and caught me off guard and reeling, too!) - but it's the only proper way to handle elements that might or might not be specified in your XML schema.

And it also might seem counter-intuitive that you have to set the xyzSpecified flag yourself - but ultimately, this gives you more control, and WCF is all about the Four Tenets of SOA of being very explicit and clear about your intentions.

So basically - that's the way it is, get used to it :-) There's no way "past" this behavior - it's the way the WCF system was designed, and for good reason, too.

What you always can do is catch and handle the this.RaisePropertyChanged("EditDate"); event and set the EditDateSpecified flag in an event handler for that event.

Answer 2

Ian, Please ignore my previous answers, was explaining how to suck eggs. I've voted to delete them.

Could you tell me which version of Visual Studio you're using, please?

In VS2005 client - in the generated code, I get the <property>Specified flags, but no event raised on change of values. To pass data I have to set the <property>Specified flag.

In Visual Web Developer 2008 Express client - in the generated code, I get no <property>Specified flags, but I do get the event on change of value.

Seems to me that this functionality has evolved and the Web Dev 2008 is closer to what you're after and is more intuitive, in that you don't need to set flags once you've set a value.

Bowthy

Answer 3

try this

[DataMember(IsRequired=true)]
public DateTime EditDate { get; set; }

This should omit the EditDateSpecified property since the field is specified as required

Answer 4

Have a look here.

Answer 5

[DataMember(IsRequired=true)]

What Neil suggested works just fine Thx for that... Would up your answer but don't have enough rep