ASP.NET MVC2 - How to create a form?

Question

How can I create a form in ASP.NET MVC2, send the data to a controller that adds something to the database and then redirects to the home page? Can you give me an example/snippet of how it's done in the View?

---

For some reason, I have a bug in my form. Here's the code:

AddEvent.aspx

<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">

<h2>Add Event</h2>
<% using (Html.BeginForm()) { %>

    <div>
        <%= Html.LabelFor(x => x.EventName) %>: 
        <%= Html.TextBoxFor(x => x.EventName) %>
    </div>
    <div>
        <%= Html.LabelFor(x => x.EventDate) %>: 
        <%= Html.TextBoxFor(x => x.EventDate) %>
    </div>
    <div>
        <%= Html.LabelFor(x => x.EventLocation) %>: 
        <%= Html.TextBoxFor(x => x.EventLocation) %>
    </div>
    <div>
        <%= Html.LabelFor(x => x.EventDescription) %>: </br> 
        <%= Html.TextAreaFor(x => x.EventDescription) %>
    </div>

    <input type="submit" value="Submit" />
<% } %>

HomeController.cs

    public ActionResult AddEvent()
    {
        return View();
    }

    [HttpPost]
    public ActionResult AddEvent(Event e)
    {
        e.EventCreatorName = Session["UserName"].ToString();
        DatabaseModels db = new DatabaseModels();
        db.AddEvent(e);

        return RedirectToAction("Index", "Home");
    }

DatabaseModels.cs

    public bool AddEvent(Event e)
    {
        anEvent eventToAdd = new anEvent();
        eventToAdd.creator_nickname = e.EventCreatorName;
        eventToAdd.event_category = 1; // TODO
        if (e.EventDate == null)
        {
            eventToAdd.event_date = new DateTime();
        }
        else
        {
            eventToAdd.event_date = DateTime.Parse(e.EventDate);
        }
        eventToAdd.event_location = e.EventLocation;
        eventToAdd.event_name = e.EventName;

        m_db.AddToevents(eventToAdd);
        m_db.SaveChanges();
        return true;
    }

I type in details in the form and I get the following Exception:

This property cannot be set to a null value.

on event_location. Can anyone help solve this?

Answer 1

The asp.net/mvc site contains numerous examples, videos and tutorials about MVC that are worth reading. Here's an example of how the scenario you are asking about could be implemented:

Model:

public class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

Controller:

public class PersonsController: Controller
{
    public ActionResult Index()
    {
        return View(new Person());
    }

    [HttpPost]
    public ActionResult Index(Person person)
    {
        // The person object here will have it's FirstName
        // and LastName properties bound to whatever values
        // the user entered in the corresponding textboxes in the form

        // TODO: save person to database 

        // redirect to /home/index
        return RedirectToAction("index", "home");
    }
}

View:

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

<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">
    <% using (Html.BeginForm()) { %>
        <div>
            <%= Html.LabelFor(x => x.FirstName) %>:
            <%= Html.TextBoxFor(x => x.FirstName) %>
        </div>

        <div>
            <%= Html.LabelFor(x => x.LastName) %>:
            <%= Html.TextBoxFor(x => x.LastName) %>
        </div>

        <input type="submit" value="Save" />
    <% } %>
</asp:Content>

Now you might be wondering about the TODO part. Usually I create a repository to decouple my data access logic from my controller:

public interface IPersonsRepository
{
    void Save(Person person);
}

and then use constructor injection of this repository into my controller:

public class PersonsController: Controller
{
    private readonly IPersonsRepository _repository;
    public PersonsController(IPersonsRepository repository)
    {
        _repository = repository;
    }

    public ActionResult Index()
    {
        return View(new Person());
    }

    [HttpPost]
    public ActionResult Index(Person person)
    {
        // The person object here will have it's FirstName
        // and LastName properties bound to whatever values
        // the user entered in the corresponding textboxes in the form

        // save person to database 
        _repository.Save(person);

        // redirect to /home/index
        return RedirectToAction("index", "home");
    }
}

Obviously now the last part that's left is the implementation of this repository. This will depend on how/where your data is stored and the particular data access technology you would be using. So are you using a relational database, flat text file, XML file, object database, some database stored on the cloud, ... how are you going to access it: EF, NHibernate, Linq-to-XML, some REST API, ...

Once you make your choice you simply implement the interface and instruct your DI framework to pass the proper implementation to the controller constructor.