interface error

[sds814]

The error I am getting is: Cannot serialize member Base.ClassLibrary.Common.Objects.ListObjects.LobjList of type Base.ClassLibrary.Interfaces.Common.Objects.IDropDownItem because it is an interface. I cannot pinpoint where the error is being thrown in the user control even though I put try catch blocks around all the events and methods that I've created in the user control.

Any suggestions on how I can trap this error? Thanks.

 

[jmeckley]

remove the try/catch and let the exception bubble up. when the error is thrown log the stacktrace. this will tell you where the error is thrown.

Jason Meckley
Programmer
Specialty Bakers, Inc.

 

[sds814]

I couldn't get any clues from the stack trace. Here it is:

[NotSupportedException: Cannot serialize member Base.ClassLibrary.Common.Objects.ListObjects.LobjList of type Base.ClassLibrary.Interfaces.Common.Objects.IDropDownItem because it is an interface.]

[InvalidOperationException: Cannot serialize member ‘Base.ClassLibrary.Common.Objects.ListObjects.LobjList' of type 'System.Collections.Generic.List`1[[Base.ClassLibrary.Interfaces.Common.Objects.IDropDownItem, Base.ClassLibrary, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null]]', see inner exception for more details.]
   System.Xml.Serialization.StructModel.CheckSupportedMember(TypeDesc typeDesc, MemberInfo member, Type type) +925156
   System.Xml.Serialization.StructModel.CheckSupportedMember(TypeDesc typeDesc, MemberInfo member, Type type) +69
   System.Xml.Serialization.StructModel.GetPropertyModel(PropertyInfo propertyInfo) +127
   System.Xml.Serialization.StructModel.GetFieldModel(MemberInfo memberInfo) +118
   System.Xml.Serialization.XmlReflectionImporter.ImportStructLikeMapping(StructModel model, String ns, Boolean openModel, XmlAttributes a) +1824
   System.Xml.Serialization.XmlReflectionImporter.ImportTypeMapping(TypeModel model, String ns, ImportContext context, String dataType, XmlAttributes a, Boolean repeats, Boolean openModel) +734

[InvalidOperationException: There was an error reflecting type Base.ClassLibrary.Common.Objects.ListObjects'.]
   System.Xml.Serialization.XmlReflectionImporter.ImportTypeMapping(TypeModel model, String ns, ImportContext context, String dataType, XmlAttributes a, Boolean repeats, Boolean openModel) +1638
   System.Xml.Serialization.XmlReflectionImporter.ImportElement(TypeModel model, XmlRootAttribute root, String defaultNamespace) +115
   System.Xml.Serialization.XmlReflectionImporter.ImportTypeMapping(Type type, XmlRootAttribute root, String defaultNamespace) +76
   System.Xml.Serialization.XmlSerializer..ctor(Type type, String defaultNamespace) +320
   System.Xml.Serialization.XmlSerializer..ctor(Type type) +6
   System.Configuration.SettingsPropertyValue.ConvertObjectToString(Object propValue, Type type, SettingsSerializeAs serializeAs, Boolean throwOnError) +524
   System.Configuration.SettingsPropertyValue.SerializePropertyValue() +91
   System.Configuration.SettingsPropertyValue.get_SerializedValue() +19
   System.Web.Profile.ProfileModule.PrepareDataForSaving(String& allNames, String& allValues, Byte[]& buf, Boolean binarySupported, SettingsPropertyValueCollection properties, Boolean userIsAuthenticated) +1207
   System.Web.Profile.SqlProfileProvider.SetPropertyValues(SettingsContext sc, SettingsPropertyValueCollection properties) +221
   System.Configuration.SettingsBase.SaveCore() +379
   System.Configuration.SettingsBase.Save() +77
   System.Web.Profile.ProfileBase.SaveWithAssert() +31
   System.Web.Profile.ProfileBase.Save() +63
   System.Web.Profile.ProfileModule.OnLeave(Object source, EventArgs eventArgs) +2397611
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +92
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +64

 

[jmeckley]

somewhere in the system you are trying to serialize an interface, which cannot happen. you need to serialize the implementation.

there may be a serializable attribute on the interface, which must be removed or you have a call to serialize to type IDropDownItem which also cannot happen, you need to serialize to the concrete type.

it could also be the error is with
List<IDropDownItem> as it's a list of interfaces, not List<Implementation of IDropDownList> which would be a concrete object.

instead of the interface IDropDownItem. I would have an immutable Lookup dto object which can be serialized.

[Serializable]
public class LookupItem
{
   public string Text {get; private set;}
   public string Value {get; private set;}

   public class LookupItem(string text, string value)
   {
      Text = text;
      Value = value;
   }
}

now you are serializing List<LookupItem>.

Jason Meckley
Programmer
Specialty Bakers, Inc.

 

[jmeckley]

better yet, since all you really need to serialize is the data, dump the list to a simple array and serialize the array.

LookupItem[] items = new List<LookupItem>().ToArray()
Serialize(items);

Jason Meckley
Programmer
Specialty Bakers, Inc.