通過TypeBuilder添加DisplayAttribute

Question

請幫助我在DisplayAttribute中添加我嘗試過的屬性，但構造函數錯誤為null

            var fieldName = string.Format("Prop{0}", fieldName);
            FieldBuilder fieldBuilder = segmentBuilder.DefineField(fieldName, typeof(string), FieldAttributes.Private);
            PropertyBuilder propertyBuilder = segmentBuilder.DefineProperty(fieldName, PropertyAttributes.HasDefault, typeof(string), null);
            MethodAttributes getSetAttr = MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.HideBySig;

            MethodBuilder getPropertyMethodBuilder = segmentBuilder.DefineMethod("get_" + fieldName, getSetAttr, typeof(string), Type.EmptyTypes);
            ILGenerator ilSetGenerator = getPropertyMethodBuilder.GetILGenerator();
            ilSetGenerator.Emit(OpCodes.Ldarg_0);
            ilSetGenerator.Emit(OpCodes.Ldfld, fieldBuilder);
            ilSetGenerator.Emit(OpCodes.Ret);                

            MethodBuilder setPropertyMethodBuilder = segmentBuilder.DefineMethod("set_" + fieldName, getSetAttr, null, new Type[] { typeof(string) });
            ILGenerator ilGetGenerator = setPropertyMethodBuilder.GetILGenerator();
            ilGetGenerator.Emit(OpCodes.Ldarg_0);
            ilGetGenerator.Emit(OpCodes.Ldarg_1);
            ilGetGenerator.Emit(OpCodes.Stfld, fieldBuilder);
            ilGetGenerator.Emit(OpCodes.Ret);

            propertyBuilder.SetGetMethod(getPropertyMethodBuilder);
            propertyBuilder.SetSetMethod(setPropertyMethodBuilder);

實際上，我期望這樣的類具有以下屬性

public class ModelClass
{
    [Display(Name = "Propery Name A")]
    public string ProperyA { get; set; }

    [Display(Name = "Propery Name B")]
    public string ProperyB { get; set; }
}

Answer 1

使用CustomAttributeBuilder構建屬性，並使用SetCustomAttribute方法將其應用於屬性：

Type[] constructorParameters = new Type[] { typeof(string)};
ConstructorInfo constructorInfo =   typeof(DisplayNameAttribute).GetConstructor(constructorParameters);
CustomAttributeBuilder displayNameAttributeBuilder = new CustomAttributeBuilder(constructorInfo, new object[] { "Property Name A"});

propertyBuilder .SetCustomAttribute(displayNameAttributeBuilder);

如果要設置其他屬性屬性，則需要使用另一個CustomAttributeBuilder構造函數設置屬性和值：

Type[] constructorParameters = new Type[0];
ConstructorInfo constructorInfo = typeof(DisplayAttribute).GetConstructor(constructorParameters);

PropertyInfo nameProperty = typeof (DisplayAttribute).GetProperty("Name");
PropertyInfo orderProperty = typeof (DisplayAttribute).GetProperty("Order");

CustomAttributeBuilder displayAttributeBuilder = new CustomAttributeBuilder(constructorInfo, new object[] {  }, new PropertyInfo[]{ nameProperty, orderProperty}, new object[]{"Prop Name", 1} );

custNamePropBldr.SetCustomAttribute(displayAttributeBuilder);