Could not create an instance of type 'Microsoft.AspNetCore.Http.HttpContext'

Question

I'm working on a chating site and I've been getting this pesky error for a while now, really don't know what it could be. I have this Model class:

public class ChatModel : PageModel
{
    public string UserName { get; set; }
    public ICollection<string> Espectators { get; set; }
    public ICollection<string> Chatters { get; set; }
    public string Mediator { get; set; }
    public Conversation Conversation{ get; set; }
    public Lazy<IConcurrentCaching> _cache { get; set; }

    public ChatModel()
    {
    }


    public ChatModel(string connString, string bulkTime, string username, ICollection<string> espectators = null, ICollection<string> chatters = null, string mediator = null, string conversationName = null)
    {
        //build the class, boring stuff
    }
    public void OnGet()
    {
    }
}

This model is part of a Razor page. This is my controller for the Chat view:

public class ChatController: Controller
{

    public ChatController()
    {

    }
    public IActionResult Chat(ChatModel model)
    {
        return View(model);
    }
}

And the call for the Controller action:

public IActionResult CreateChat(string username, string conversationName)
    {
        if (_cache.Value.Get<List<string>>("ChatList") == null)
        {
            _cache.Value.Set<List<string>>("ChatList", new List<string>(), 1440);
        }
        ChatModel model = new ChatModel(_op.Value.ConnectionString, _op.Value.BulkLoadCacheTimeInMinutes, username, conversationName: conversationName);
        model.Chatters.Add(username);
        return RedirectToAction("Chat","Chat", model);
    }

For some reason, when I call the controller method for the Chat view, it throws the following exception:

InvalidOperationException: Could not create an instance of type 'Microsoft.AspNetCore.Http.HttpContext'. Model bound complex types must not be abstract or value types and must have a parameterless constructor. Alternatively, set the 'HttpContext' property to a non-null value in the 'Chatter.UI.Web.Views.Chat.ChatModel' constructor. Microsoft.AspNetCore.Mvc.ModelBinding.Binders.ComplexTypeModelBinder.CreateModel(ModelBindingContext bindingContext)

The weirdest thing is that I'm not even using HttpContext on the ChatModel class. I have tried using DI to inject the IHttpContextAccessor on my class (even though I don't see how that would help, but I've seen that as a solution online); it did't work. I've also tried to add a singleton on the startup for the HttpContext, but to no avail. Any ideas on what is going on would be greatly appreciated.

Your ChatModal class is supposed to have default parameterless constructor only as far as I know — Hasan Emrah Süngü
– Hasan Emrah Süngü, Commented Oct 4, 2019 at 4:04
Why is the ChatModel a PageModel? Seems like you're mixing RazorPages and Mvc in a strange way — davidfowl
– davidfowl, Commented Oct 4, 2019 at 6:54
I am new to Razor pages, are the razor page models not interchangeable with MVC models? — Postman
– Postman, Commented Oct 4, 2019 at 17:18

Edward · Accepted Answer · 2019-10-07 07:17:58Z

5

You should not combine PageModel and Controller.

As the error indicates, Model bound complex types must not be abstract or value types and must have a parameterless constructor. For ChatModel which inherits PageModel is abstract class.

Create a new separate class for use in Controller action.

answered Oct 7, 2019 at 7:17

Edward

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Comments

Jeremy Caney · Accepted Answer · 2022-03-31 00:02:22Z

-1

using Microsoft.AspNetCore.Mvc;

namespace sucu1.Models
{
    public class LoginViewModel : Controller
    {

        public string? Mail { get; set; }
        public string? Password { get; set; }
    }
}

edited Mar 31, 2022 at 0:02

Jeremy Caney

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answered Mar 31, 2022 at 0:00

ömür karagülle

12 bronze badges

1 Comment

Jeremy Caney Over a year ago

As it’s currently written, your answer is unclear. Please edit to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers in the help center.

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