ASP.NET MVC - Passing a Model referencing a different assembly from a Controller to a View using C#

Question

Given two assemblies:

project.web
project.lib

The project.web assembly references project.lib which contains some business logic. A simple class from project.lib:

public class Person
{
    public string Name;
}

In project.web.Controllers:

Using project.lib.models;

public class PersonController : Controller
{
    Person person = new Person();

    public ActionResult Index()
    {
        return View(person);
    }
}

This is the part where I have some questions. In a lot of sample projects I've seen the following in the View (in this case Index.aspx):

<% @Import Namespace="project.lib.models" %>

Allowing you to use the Model object like this:

<%= Model.Name %>

I haven't gotten that to work like the examples, I've had to do:

<%= (Model as Person).Name %>

or

<%
    var person = (Person)Model;
    Response.Write(person.Name);
%>

Why is this thus? What is the reason for this thusness? Comments? Suggestions? My class definition looks like this:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace project.lib.models
{
    public class Person
    {
        public Int64 PersonID;
        public string DisplayName;
        public string RealName;
    }
}

Answer 1

Your view may not be strongly typed. Try the following:

1. Copy the View markup
2. Delete the View
3. Go to the controller action that drives the View
4. Right click within this method, select the Add View option.
5. Ensure that this is a Strongly typed view and that you properly identify the type of your intended model.
6. Paste your View markup into the newly created view.

This should work. It doesn't look like you're missing an assembly because you're able to cast the model correctly.

It should be noted that you can do the above without the pain of deleting/restoring a View. Each view has a declaration as its first line that is similar to the following:

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<DomainModel.Person>" %>

The important section to understand is the Inherits attribute, which implies that this View extends the MVC ViewPage<DomainModel.Person> class. The Model property will be of type DomainModel.Person at runtime.

Also, there are issues with previous versions of ASP.NET MVC that effectively prevent strongly-typed views from working correctly. See http://stackoverflow.com/questions/492671/problem-using-add-view-dialog-in-asp-net-mvc-rc1-for-strongly-typed-view for more detail.

EDIT: After a bit of detective work by everyone who has posted here, it looks like Visual Studio was referencing older versions of the assembly containing the Person class. Closing the development environment down, clearing out all obj/bin folders, and restarting seems to have fixed this issue.

Answer 2

Could you please post your <%@ Page %> directive? It should be something like:

<%@ Page Language="C#"
         [...]
         Inherits="System.Web.Mvc.ViewPage<project.lib.models.Person>" %>

Have you tried creating a strongly typed code-behind file for this view instead?

You'd need to update the inherits property of the view to be the code-behind file:

<%@ Page Language="C#" 
    CodeBehind="Index.aspx.cs" Inherits="project.web.Views.People.Index" %>

and then in the code-behind:

namespace project.web.Views.People.Index {
  public partial class Index : System.Web.Mvc.ViewPage<project.lib.models.Person>
  {}
}

I don't think it's an issue with resolving the System.Web.Mvc.ViewPage class as then the page wouldn't load (you'd get an exception along the lines that System.Web.Mvc.ViewPage cannot be found), and you wouldn't even be able to access the Model property.

Answer 3

What version of System.Web.MVC are you using?

Answer 4

Update 1: Note that you can be pretty certain that it isn't an issue loading/getting to the types System.Web.Mvc.ViewPage or project.lib.models.Person. As you mentioned in your question, it does work when you use:

<% @Import Namespace="project.lib.models" %>
...
<%= (Model as Person).Name %>

Using System.Web.Mvc.ViewPage<project.lib.models.Person> on the page directive and <%= Model.Name %> must work. Some extra things I would try if that doesn't work:

• Remove the import directive when doing so.
• Check if you have that namespace added on the web.config.

While none of those 2 above should cause any trouble, if you don't get it to work with what is mentioned before that, it would be a very weird scenario. Also note that if you did add commonly used namespaces in the web.config you can use ViewPage<Person> on the page directive.

---

The Model.Name you refer to doesn't have to do with importing the namespace, you get it from the type you set in the page directive.

The ViewPage class has the property T Model, which is why you get access to the Name property (you are working with the type you specified).

Answer 5

to do that your view should be strongly typed to your model object in your case the Person class

all you need to make it work is adding refrence to the project.lib and adding updating the page derictive :

<%@ Page Title="" Language="C#" Inherits="System.Web.Mvc.ViewPage<Project.lib.Models.Person>" %>