ASP.NET MVC2 - How to create a form? - asp.net-mvc-2

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.