ASP.NET MVC Passing models by ActionLink

Question

I would like to pass a model and an int to a controller upon clicking an ActionLink.

@Html.ActionLink("Next", "Lookup", "User", new { m = Model.UserLookupViewModel, page = Model.UserLookupViewModel.curPage }, null)

Does not work, instead it passes a blank instance of the model, which one would expect when using new.

@Html.ActionLink("Next", "Lookup", "User", Model.UserLookupViewModel, null)

Does work.

Controller

[HttpGet]
public ActionResult Lookup(UserLookupViewModel m, int page = 0)
{
    return this.DoLookup(m, page);
}

View model

public class UserLookupViewModel
{
    public int curPage { get; set; }

    [Display(Name = "Forenames")]
    public string Forenames { get; set; }

    [Display(Name = "Surname")]
    public string Surname { get; set; }

    [Display(Name = "DOB")]
    public DateTime? DoB { get; set; }

    [Display(Name = "Post code")]
    public string Postcode { get; set; }
}

How can I pass them together? The Lookup method's arguments match the named properties in the ActionLink.

Answer 1

You can't use an ActionLink to pass properties with a Link but you can do the following to get the same behavior.

<form action="/url/to/action" Method="GET">   <input type="hidden" name="Property" value="hello,world" />   <button type="submit">Go To User</button> </form> 

If you create a helper to generate these GET forms, you will be able to style them like they are regular link buttons. The only thing I caution against is that ALL forms on the page are susceptible to modification so I wouldn't trust the data. I'd rather just pull the data again when you get to where you are going.

I use the technique above when creating search actions and want to retain a search history and keep the back button working.

Hope this helps,

Khalid :)

---

P.S.

The reason this works.

@Html.ActionLink("Next", "Lookup", "User", Model.UserLookupViewModel, null) 

Is because the parameter list of the ActionLink method is generalized to take an object, so it will take anything. What it will do with that object is pass it to a RouteValueDictionary and then try to create a querystring based on the properties of that object.

If you say that method is working above, you could also just try adding a new property to the viewmodel called Id and it will work like you wanted it to.

Answer 2

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("Next", "Lookup", "User", new { JSONModel = Json.Encode(Model.UserLookupViewModel), page = Model.UserLookupViewModel.curPage }, null)

In your controller, you'll need a method to turn your JSON data into a MemoryStream:

private Stream GenerateStreamFromString(string s)
{
  MemoryStream stream = new MemoryStream();
  StreamWriter writer = new StreamWriter(stream);
  writer.Write(s);
  writer.Flush();
  stream.Position = 0;
  return stream;
}

In your ActionResult, you turn the JSON string into an object:

public ActionResult YourAction(string JSONModel, int page)
{
  DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(Model.UserLookupViewModel));
  var yourobject =  (UserLookupViewModel)ser.ReadObject(GenerateStreamFromString(JSONModel));
}