TryUpdateModelAsync not working in ASP․NET Core 3.1

Describe the bug

The TryUpdateModelAsync not working as expected in ASP․NET Core 3.1.

To Reproduce

1. Setup demo project

   git clone https://github.com/doggy8088/TryUpdateModelAsyncProblem.git
   cd TryUpdateModelAsyncProblem
   dotnet run
   

2. Send HTTP request to the demo action

   curl --location --request POST 'https://localhost:5001/WeatherForecast' --header 'Content-Type: application/json' --data-raw '{"Date": "2019-12-01", "TemperatureC": 1, "Summary": "N/A"}' -k -D -
   

The TryUpdateModelAsync should do the manual model binding under the hood. If I use [FromBody] in the parameter of the Action, it works. I’m trying to do the manual model binding in the action, but failed.

Here is the code snippet of the demo code:

[HttpPost]
public async Task<IActionResult> PostAsync()
{
	var value = new WeatherForecast()
	{
		Date = DateTime.Parse("2019-12-14"),
		TemperatureC = 100,
		Summary = ""
	};

	if (await TryUpdateModelAsync(value, ""))
	{
		return CreatedAtAction("Get", value);
	}
	else
	{
		return BadRequest();
	}
}

The original value’s Date property is 2019-12-14. When I do the request, I pass a new Date as 2019-12-01. So the expected result should be:

HTTP/2 201
date: Sat, 14 Dec 2019 11:19:38 GMT
content-type: application/json; charset=utf-8
location: https://localhost:5001/WeatherForecast
server: Kestrel

{"date":"2019-12-01T00:00:00+08:00","temperatureC":1,"temperatureF":33,"summary":"N/A"}

But the actual result is: ( The TryUpdateModelAsync is not working. )

HTTP/2 201
date: Sat, 14 Dec 2019 11:19:38 GMT
content-type: application/json; charset=utf-8
location: https://localhost:5001/WeatherForecast
server: Kestrel

{"date":"2019-12-14T00:00:00+08:00","temperatureC":100,"temperatureF":211,"summary":""}

Further technical details

• ASP.NET Core version: 3.1
• Include the output of dotnet --info: See below
• The IDE (VS / VS Code/ VS4Mac) you’re running on, and it’s version: VSCode 1.39.2

.NET Core SDK (reflecting any global.json):
 Version:   3.1.100
 Commit:    cd82f021f4

Runtime Environment:
 OS Name:     ubuntu
 OS Version:  18.04
 OS Platform: Linux
 RID:         ubuntu.18.04-x64
 Base Path:   /usr/share/dotnet/sdk/3.1.100/

Host (useful for support):
  Version: 3.1.0
  Commit:  157910edee

.NET Core SDKs installed:
  2.1.802 [/usr/share/dotnet/sdk]
  3.0.100 [/usr/share/dotnet/sdk]
  3.1.100 [/usr/share/dotnet/sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.All 2.1.14 [/usr/share/dotnet/shared/Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.14 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.0.0 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.0 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.14 [/usr/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.0.0 [/usr/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.0 [/usr/share/dotnet/shared/Microsoft.NETCore.App]

To install additional .NET Core runtimes or SDKs:
  https://aka.ms/dotnet-download

[pranavkm]

Thanks @kishanAnem for the investigation. This is not a feature ASP.NET Core MVC has. https://github.com/aspnet/Mvc/issues/5659#issuecomment-270717629 goes in to some details as to why along with possible solutions to this.

[kishanAnem]

@doggy8088 yeah it’s right working MVC 5. In Asp.net community standup I think @DamianEdwards said “ removed that feature consciously”.