Model value redirected to another action does not pass all values

Question

I have an ASP.Net Core application which needs passing of a model from one action to another.

These are models :

public class ClassA
{
    public string Id{get;set;}
    public string Name {get;set;}
    public StudentMarks Marks {get;set;}
}

public class StudentMarks
{
    public int Marks {get;set;}
    public string Grade {get;set;}
}

And the post Controller:

[HttpPost]
public ActionResult TestAction1(ClassA model)
{   
    return RedirectToAction("TestAction2", model);
}

public ActionResult TestAction2(ClassA model)
{


}

In TestAction 1 while debugging, i see that Id, Name and marks have value.

I am getting the value for Id in TestAction2 same as that in TestAction1. However the value of complex object Marks is not obtained in the TestAction2 action method.

What are my other options?

Maybe try `RedirectToAction("TestAction2", new { model = model });` — Izzy, Aug 06 '19 at 12:05
There maybe some pointers here: https://stackoverflow.com/questions/22505674/can-we-pass-model-as-a-parameter-in-redirecttoaction — theduck, Aug 06 '19 at 12:07
What about a simple `return TestAction2(model)` rather than a `RedirectToAction`. You can also make use of `TempData` — Izzy, Aug 06 '19 at 12:19
Small point, but shouldn't your Class A class have StudentMarks as the type 'StudentMarks'. If not, then what is Marks? — sr28, Aug 06 '19 at 12:21
@sr28 Yeah thanks. I was trying to replicate a simplified version of my class and messed up. — TheFallenOne, Aug 06 '19 at 12:24
A redirect like that will always be a GET-request; can you show the full URL that the redirect will point to? You should be able to inspect that via the browser. — Dennis, Aug 06 '19 at 12:26
While debugging, `Marks` are present in `TestAction1` before `RedirectToAction`? — Gonzalo Lorieto, Aug 06 '19 at 12:33
@GonzaloLorieto Yes. That is why I am not understanding as to why it goes null. — TheFallenOne, Aug 06 '19 at 12:35
Take a look here a issues with complex model binding: https://github.com/aspnet/Mvc/issues/5093 — sr28, Aug 06 '19 at 12:47

score 2 · Answer 1 · answered Aug 06 '19 at 12:57

You cannot redirect with a model. A redirect is simply an empty response with a 301, 302, or 307 status code, and a Location response header. That Location header contains the the URL you'd like to redirect the client to.

The client then must make a new request to that URL in the header, if it so chooses. Browsers will do this automatically, but not all HTTP clients will. Importantly, this new request is made via a GET, and GET requests do not have bodies. (Technically, the HTTP spec allows for it, but no browser or HTTP client out there actually supports that.)

It's unclear what your ultimate goal is here, but if you need to persist data temporarily between requests (such as a redirect), then you should serialize that data into a TempData key.

Rahul Sharma · Answer 2 · 2019-08-21T12:24:14.790

You can use TempData to pass model data to a redirect request in Asp.Net Core In Asp.Net core, you cannot pass complex types in TempData. You can pass simple types like string, int, Guid etc. If you want to pass a complex type object via TempData, you have can serialize your object to a string and pass that. I have made a simple test application that will suffice to your needs:

Controller:

public ActionResult TestAction1(ClassA model)
{
    model.Id = "1";
    model.Name = "test";
    model.Marks.Grade = "A";
    model.Marks.Marks = 100;
    var complexObj = JsonConvert.SerializeObject(model);
    TempData["newuser"] = complexObj;
    return RedirectToAction("TestAction2");
}

public ActionResult TestAction2()
{
    if (TempData["newuser"] is string complexObj )
    {
        var getModel= JsonConvert.DeserializeObject<ClassA>(complexObj);
    }
    return View();
}

Model:

public class ClassA
{
    public ClassA()
    {
        Marks = new StudentMarks();
    }

    public string Id { get; set; }
    public string Name { get; set; }
    public StudentMarks Marks { get; set; }
}

public class StudentMarks
{
    public int Marks { get; set; }
    public string Grade { get; set; }
}

If you want to persist your TempData values for more requests you can use Peek and Keep functions. This answer can give more insight on these functions.

score 0 · Answer 3 · answered Aug 06 '19 at 12:57

I think you're getting model and routeValues mixed up. The overload of RedirectToAction that you're calling (takes a string and an object) expects a routeValues argument, not a model argument. https://learn.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.mvc.controllerbase.redirecttoaction?view=aspnetcore-2.2

TestAction1 is called via Post, but TestAction2 is called via Get. You need to work out a URL that will let you call TestAction2 the way you want (independently of the RedirectToAction in TestAction1). I'm guessing this will involve setting up a custom route. Once you have a URL that will let you call TestAction2 the way you want, you can specify the route values to form that URL in the RedirectToAction in TestAction1.

score -1 · Answer 4 · answered Aug 06 '19 at 12:47

-1

I think the problem is that you shuold use:

return RedirectToAction("TestAction2", model);

(you did this without return)

answered Aug 06 '19 at 12:47

Efraim Newman

927
6
21

Wouldn't the compiler show an Error if you only write `RedirectToAction` without return? – Rahul Sharma Aug 06 '19 at 12:49

Model value redirected to another action does not pass all values

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