C# Object Initializers and ConstructorInfo

Question

Can anyone point me towards a solution for the following? I am trying to replicate a property attribute that uses Object Initializers by using the CustomAttributeBuilder;

ie.

[Display(Order = 0, Name = "UserNameLabel", ResourceType = typeof(RegistrationDataResources))]

as..

//Add Display Attribute 
ConstructorInfo displayCtor = typeof(DisplayAttribute).GetConstructor(new Type[] { /* something here? */ });
CustomAttributeBuilder displayAttrib = new CustomAttributeBuilder(displayCtor, new object[] { /*..*/});
propertyBuilder.SetCustomAttribute(displayAttrib);

Answer 1

It seems that you need to use constructor of CustomAttributeBuilder that allows you to specify properties and their values. Did you try this?

        ConstructorInfo displayCtor = typeof(TestAttribute).GetConstructor(new Type[] {});
        PropertyInfo conProperty = typeof (TestAttribute).GetProperty("TestProperty");
        CustomAttributeBuilder displayAttrib = new CustomAttributeBuilder(displayCtor, new object[] {}, new[] {conProperty}, new object[] {"Hello"});

The above code goes for:

    [Test(TestProperty = "Hello")]

Also note that in your example your attribute "Display" does not match the constructor "DataValidationAttribute"

Edit:

Complete sample:

using System;
using System.Reflection;
using System.Reflection.Emit;
using System.Threading;

namespace SO5841769
{

    class TestAttribute : Attribute
    {
        public string TestProperty { get; set; }
    }

    class Program
    {
        static void Main(string[] args)
        {
            AppDomain myDomain = Thread.GetDomain();
            AssemblyName myAsmName = new AssemblyName();
            myAsmName.Name = "MyDynamicAssembly";
            AssemblyBuilder myAsmBuilder = myDomain.DefineDynamicAssembly(myAsmName, AssemblyBuilderAccess.RunAndSave);
            ModuleBuilder myModBuilder = myAsmBuilder.DefineDynamicModule(myAsmName.Name, myAsmName.Name + ".dll");
            TypeBuilder myTypeBuilder = myModBuilder.DefineType("Data", TypeAttributes.Public);
            FieldBuilder someFieldBuilder = myTypeBuilder.DefineField("someField", typeof(string), FieldAttributes.Private); 
            PropertyBuilder somePropertyBuilder = myTypeBuilder.DefineProperty("SomeProperty", PropertyAttributes.HasDefault, typeof(string), null);
            MethodAttributes getSetAttr = MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.HideBySig;
            ConstructorInfo displayCtor = typeof(TestAttribute).GetConstructor(new Type[] { });
            PropertyInfo conProperty = typeof (TestAttribute).GetProperty("TestProperty");
            CustomAttributeBuilder displayAttrib = new CustomAttributeBuilder(displayCtor, new object[] {}, new[] {conProperty}, new object[] {"Hello"});
            somePropertyBuilder.SetCustomAttribute(displayAttrib);
            MethodBuilder somePropertyGetPropMthdBldr = myTypeBuilder.DefineMethod("get_SomeProperty", getSetAttr, typeof(string), Type.EmptyTypes);
            ILGenerator somePropertyGetIL = somePropertyGetPropMthdBldr.GetILGenerator();
            somePropertyGetIL.Emit(OpCodes.Ldarg_0);
            somePropertyGetIL.Emit(OpCodes.Ldfld, someFieldBuilder);
            somePropertyGetIL.Emit(OpCodes.Ret);
            somePropertyBuilder.SetGetMethod(somePropertyGetPropMthdBldr);
            myTypeBuilder.CreateType();
            myAsmBuilder.Save(myAsmName.Name + ".dll");

        }
    }
}