Mvc: No parameterless Constructor defined

[fhnainia]

When posting a form with a POCO object and FormCollection object to a Controller Action a SystemMethodException occurs. This was working fine in RC1 but since the upgrade to RC2 the exception started.
Here is the part of the Action:

// POST: Candidate/Create
        [Authorize]
        [HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> Create(Candidate candidate, FormCollection obj, IList<IFormFile> files)
        {
            var auser = await _userManager.FindByNameAsync(User.Identity.Name);
            var employee = _employeeService.GetEmployee(auser.Id);
            if (employee != null && employee.PartnerId != null)
            { 
                ViewBag.PartnerId = employee.PartnerId;
            }
       ...
       }

[rynowak]

This should be IFormCollection instead of FormCollection, we intentionally dropped support for the concrete type here in RC2 because IFormFeature is replaceable.

[fhnainia]

That did it. Thanks.

[pranavkm]

@rynowak - does the exception message include the type that couldn't be constructed? If not, should we modify places where we call CreateInstance to try-catch and explicitly call out the object type?

[rynowak]

We should also consider handling this within the provider. Then you'd get an error about "could not create a model binder for type foo". We don't need to do anything fancy, just have the complex type binder check for a no-arg constructor.

[rynowak]

@fhnainia glad we could help. Let's keep the bug open for now to track and improvement in the experience when this happens.

[rynowak]

@kichalla - please discuss with me and @dougbu before starting