ASP.NET MVC & C#：将视图模型传递给控制器

Question

I have a controller that passes the viewmodel to a view, and in the view it creates the table correctly.

Then in the same page of the table I have a link that redirects the user to another page.

This new page needs to keep the viewmodel of the previous view. How could I do it?

In the view, in the table page this link that should redirect to an action of EanMatch controller:

@Html.ActionLink("Inserimento manuale", "Index", "EanMatch",  null, new {Vm = Model})

The model is this:

public List<DDTViewModel> DDTList { get; set; }

In the EanMatchController and Index action I have:

[HttpGet]
public ActionResult Index(DDTListViewModel Vm)
{
    ....
}

I can't understand why it doesn't work. DDTListViewModel Vm in Index actions takes 'null' value, meanwhile I have seen with debug that Model got the list of data.

How can I pass the viewmodel to the action argument correctly?

Any doubt, ask !

Answer 1

For your particular case, You'll have to serialize your model as a JSON string, and send that to your controller to turn into an object.

Here's your ActionLink :

@Html.ActionLink("Inserimento manuale", "Index", "EanMatch",  new { jsonModel= Json.Encode(Model.DDTListViewModel) }, null)

And your Controller method would look like:

public ActionResult Index(string jsonModel)
{
  var serializer= new DataContractJsonSerializer(typeof(Model.DDTListViewModel));
  var yourmodel=  (DDTListViewModel)serializer.ReadObject(GenerateStreamFromString(jsonModel));
}

Answer 2

if you controller name is EanMatch, then the next issue is that I think you are passing the model in where it expects htmlattributes. So instead of null, new {Vm = Model}; switch them.

@Html.ActionLink("Inserimento manuale", "Index", "EanMatch", new {Vm = Model} ,null )

Answer 3

Try this:

@Html.ActionLink("Inserimento manuale", "Index", "EanMatch",  null,  Model)

OR: Each request to the server has its own context(thread) and doesn't know anything about others. If you need to share a model or another data between a few different requests to the server you can use temp data or session . Inside of the first action, you need to save this model:

Session["myModel"] = Model;

and read in another:

var val = Session["myModel"];

Answer 4

You don't need to create the anonymous object, just pass your view model:

@Html.ActionLink("Inserimento manuale", "Index", "EanMatch", null, Model)

The framework will convert your model to a query string that will be bound by your controller.

Answer 5

@Html.ActionLink("LinkName", "Index", "EanMatchController", new ViewModel { Id = 1, Name = "Sth", Description = "Hello" }, null);

You set the object as property to an anonymous object. This is why your object is not passed on the controller.

It is like having a wrapper object around your object like below.

public class Sth{
 public ViewModel { get; set; }
}

So C# does not recognize this as your object you need to somehow create it inside razor and send it back to the controller. The code above works. Try a simple example.