Passing complex object from view to controller/view in ASP.NET MVC

Question

In my MVC application I have a problem with passing data from view to controller. I have fairly complex domain classes:

public class TaskBase : PersistableObject
{
    public virtual TaskCategory Category { get; set; }
    public virtual IList<TaskNote> Notes { get; set; }
    public virtual string TaskTitle { get; set; }
    public virtual string TaskBody { get; set; }
    public virtual DateTime? CreationTime { get; set; }
    public virtual User CreatedBy { get; set; }
    public virtual int CompletionRatio { get; set; }
}

public class MainTask : TaskBase
{
    public virtual IList<TaskBase> ChildTasks { get; set; }
    public virtual User AssignedTo { get; set; }
    public virtual IList<TaskHistory> History { get; set; }
}

public class TaskFormModel : ViewDomainBase
{
    public MainTask Task { get; set; }
    public LoginForm LoginInfo { get; set; }
}

And in my view I want to pass an instance of TaskFormModel to the controller.

<%= Html.ActionLink<TaskController>("Edit Task", (x) => x.Edit(new TaskFormModel() { Task = item, LoginInfo = Model.LoginInfo }))%>

And here is the controller action:

public ActionResult Edit (TaskFormModel taskInfo)
{
    return View(ViewPageName.TaskDetailsForm, task.Task);
}

In this action method taskInfo comes null even if I pass non-null instance from view. I think I have a binding problem here. I think, writing custom model binder requires every property to be converted and also when new fields added then binder class should also be changed, so I don't want custom model binder to do this. Is there any other way to pass data to controller in this scenario? Or could custom model binder can be coded so that less code written and also when new properies are added binder class will not need to be changed?

Edit After Comments: What I am trying to achieve is basically to pass an instance from one view to another view, without querying repository/db in my controller's action.

Answer 1

First version of answer:

Your GET edit method should be like:

public ActionResult Edit (int id)
{
    var model = taskRepository.GetTaskEditModel(id);
    return View(ViewPageName.TaskDetailsForm, model);
}

and ActionLink:

<%= Html.ActionLink("Edit Task", "Edit", "Task", new { model.Task.id })%>

If you want to pass complex objects to controller, you should wrap them up in html form and pass to POST action.

Answer 2

In my opinion you are doing something wrong. As I understand: you are trying to instantiate a new object, pass it to browser and get it back. well you cant.

If object you want to edit exists already in your storage, then you should alter your ActionLink to reference it by id, and instantiate it inside your Edit action.

Take a look at default strongly typed index views created by tooling.