Is it possible to have a non-public parameterless constructor that can be used for model binding?

Question

I have a following POCO class. I don not want the parameterless constructor to be public.

public class FileDownloadRequest
    {
       //public FileDownloadRequ         


        

Answer 1

Yes, you can use any constructor you like, but you will have to do the model binding yourself then. The problem is in DefaultModelBinder.CreateModel, which uses a parameterless public constructor.

You have to override the default model binder and create your own. If that is worth the time is up to you.

Steps to take:

• Override CreateModel;
• Check the modelType for some generic constraint which models you need to call the constructor with parameters on;
• Call Activator.CreateInstance(Type, Object[]) with the parameters. You could obtain their values from the bindingContext;
• Register the model binder, either through the ModelBinder attribute, or globally.

Read more on custom bindings here.