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11/06/2009 at 05:43AM PST, ID: 24877791 | Points: 500
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Using Reflection.Emit, how can I flag a dynamically created property in an emitted class as WCF-DataMember?

Asked by farmed in WPF and Silverlight, Web Services and WCF, .NET Framework 3.x versions

Tags: Microsoft Silverlight WCF Windows Communication Foundation Reflection Typebuilder Emit Serialize Serializable DataMember Data Attribute

Hi,

regarding the topics question:

Following this code http://www.codeproject.com/KB/tabs/CustomPropGrid.aspx?df=100&forumid=32723&exp=0&select=864615 I made up some code to dynamically create a new instance of a new type.

I am dynamically reading a database (ColumnName + Value) and want to pass these two values x-times into a newly generated property using emit.

Example for Database (needs to be dynamically!):
ID--Name--SomeOther
4---Foo-----Bar
1---Foo2---Bar2

and so on.
So I am dynamically generating a new instance of type <randomNameHere> and adding properties this way:

                              Object1                                  Object2
Prop ID                   Value: 4                                 Value: 1
Prop Name             Value: Foo                             Value: Foo2
Prop SomeOther    Value: Bar                             Value: Bar2

I am doing this work on a WCF-Service, which consumes DSN and Select-Statement from a Silverlight-App.

And I need to pass this newly generated List<myDynObjectw/dynProps> back to silverlight.

Is this possible? I need to know, how to flag the Properties as WCF-DataMembers, or to get them serializable.

My WCF-Service is using ADO.NET Entity Framework, .NET 3.5. Silverlight is the latest release.
Visual Studio 2008, 2010 Beta2


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//WCF-Service 
// the service's method has a List<object> as return value, which is gracefully filled! No problems until communication with silverlight! 
//Emit 
public class PropertyAccessor
    {
        private ArrayList customObjects = new ArrayList(); 
        public object GenerateDynProp(List<MyProp> myprops)
        {
            Type newType = CreateType("test", myprops); 
            object newObj = CreateNewInstance(newType, myprops); 
            return newObj;
        } 
        private Type CreateType(string name, List<MyProp> props)
        {
            AssemblyName _assemblyName = new AssemblyName();
            _assemblyName.Name = name;
            AssemblyBuilder _assemblyBuilder = Thread.GetDomain().DefineDynamicAssembly(_assemblyName, AssemblyBuilderAccess.RunAndSave);
            
            ModuleBuilder _module = default(ModuleBuilder);
            _module = _assemblyBuilder.DefineDynamicModule(name + ".exe"); 
            TypeBuilder tb = _module.DefineType(name + "Type", TypeAttributes.Public | TypeAttributes.Serializable, typeof(clsDummy)); 
            foreach (MyProp item in props)
                AddProperty(item, tb); 
            return tb.CreateType();
        } 
        public void AddProperty(MyProp prop, TypeBuilder tb)
        { 
            //// Create some private fields
            FieldBuilder field1 = tb.DefineField("_" + prop.Name, prop.Type, FieldAttributes.Private); 
            //// Create some public properties
            PropertyBuilder field1Prop = tb.DefineProperty(prop.Name, PropertyAttributes.HasDefault, prop.Type, new Type[] { prop.Type }); 
            //Get
            MethodBuilder field1PropGet = tb.DefineMethod("Get" + prop.Name, MethodAttributes.Public, prop.Type, new Type[] { prop.Type }); 
            //Generate the IL
            ILGenerator field1PropGetIL = field1PropGet.GetILGenerator(); 
            field1PropGetIL.Emit(OpCodes.Ldarg_0);
            field1PropGetIL.Emit(OpCodes.Ldfld, field1);
            //load field1
            field1PropGetIL.Emit(OpCodes.Ret); 
            //Set
            MethodBuilder field1PropSet = tb.DefineMethod("Set" + prop.Name, MethodAttributes.Public, null, new Type[] { typeof(string) }); 
            //Generate the IL
            ILGenerator field1PropSetIL = field1PropSet.GetILGenerator(); 
            field1PropSetIL.Emit(OpCodes.Ldarg_0);
            field1PropSetIL.Emit(OpCodes.Ldarg_1);
            field1PropSetIL.Emit(OpCodes.Stfld, field1);
            //set field1
            field1PropSetIL.Emit(OpCodes.Ret); 
            //// map the methods to the Set/Get of the Field1 property
            field1Prop.SetGetMethod(field1PropGet);
            field1Prop.SetSetMethod(field1PropSet); 
        } 
        private object CreateNewInstance(Type newType, List<MyProp> props)
        {
            object newTypeInstance = Activator.CreateInstance(newType); 
            foreach (MyProp item in props)
            {
                newType.InvokeMember(item.Name, BindingFlags.SetProperty, null, newTypeInstance, new object[] { item.Value }); 
            } 
            return newTypeInstance;
        } 
    } 
    [Serializable()]
    public class MyProp
    {
        [global::System.Runtime.Serialization.DataMemberAttribute()]
        public string Name { get; set; } 
        [global::System.Runtime.Serialization.DataMemberAttribute()]
        public string Value { get; set; } 
        [global::System.Runtime.Serialization.DataMemberAttribute()]
        public Type Type { get; set; }
    } 
 
 
 
// Silverlight app 
// In here, the error occurs while calling base.EndInvoke<....>  
// clsDummy is an Empty class with Serializable()-Attribute 
 public System.Collections.ObjectModel.ObservableCollection<Shared.ServiceReference.clsDummy> EndExecuteSelect(System.IAsyncResult result) {
                object[] _args = new object[0];
                System.Collections.ObjectModel.ObservableCollection<Shared.ServiceReference.clsDummy> _result = ((System.Collections.ObjectModel.ObservableCollection<Shared.ServiceReference.clsDummy>)(base.EndInvoke("ExecuteSelect", _args, result)));
                return _result;
            }
 
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