1. Separation of concerns
SoC in MVC is not about separation business logic from UI. More importantly, it gives Controller main functions:
- to fill View Model from Domain Model;
- to handle View activity;
- to show views depending on Domain logic.
View is responsible only for data representation in MVC.
It makes testing very simple as Controller operates pure View Model classes, opposed to WebForms which operates events and Form.
In WebForms View handles all UI activity and it basically makes decisions about scenario flow.
Here I'd like to mention that terms of View Model and Domain Model are different. Domain Model is a term describing all the services, Business logic and DAL hidden from Controller with some facade. And View Model is a class that encapsulates data required by View. It may be shared by Domain Model in simple cases. Why two classes?
Here are similar code snippets of ASP.NET MVC and WebForms doing the same things: 1) get data 2) handle data submission. In both cases I assume that IDomainModel is injected.
MVC:
public class SomeController : Controller
{
// injected
public IDomainModel Domain { get; set; }
public ViewResult Edit()
{
var record = Domain.GetRecord(1);
var dictionary = Domain.GetSomeDictionary();
var model = new SomeViewModel(record, dictionary);
return View(model);
}
[HttpPost]
public ActionResult Edit(SomeViewModel model)
{
if (ModelState.IsValid)
// save
return RedirectToAction("Result");
else
return View(model);
}
}
WebForms:
public partial class SomePage : System.Web.UI.Page
{
// injected
public IDomainModel Domain { get; set; }
protected void Page_Load(object sender, EventArgs e)
{
var record = Domain.GetRecord(1);
var dictionary = Domain.GetSomeDictionary();
RecordId.Text = record.Id.ToString();
RecordName.Text = record.Name;
RecordDescription.Text = record.Description;
DicValue.DataSource = dictionary;
DicValue.DataValueField = "Id";
DicValue.DataTextField = "Value";
DicValue.SelectedValue = record.DictionaryEntryId.ToString();
DicValue.DataBind();
}
protected void btnSave_Click(object sender, EventArgs e)
{
var record = new RecordModel
{
Id = Int32.Parse(this.RecordId.Text),
Name = this.RecordName.Text,
Description = this.RecordDescription.Text,
DictionaryEntryId = Int32.Parse(this.DicValue.Text)
};
// save
}
}
Testing MVC controller Edit GET is incredibly simple:
[TestMethod]
public void EditGetTest()
{
SomeController target = new SomeController();
var record = new RecordModel { Id = 1, Name = "name1", Description = "desc1", DictionaryEntryId = 1 };
var dictionary = new List<SomeDictionaryEntry>
{
new SomeDictionaryEntry { Id = 1, Value = "test" }
};
target.Domain = new SimpleMVCApp.Models.Fakes.StubIDomainModel()
{
GetRecordInt32 = (id) => { return record; },
GetSomeDictionary = () => { return dictionary; }
};
var result = target.Edit();
var actualModel = (SomeViewModel)result.Model;
Assert.AreEqual(1, actualModel.Id);
Assert.AreEqual("name1", actualModel.Name);
Assert.AreEqual("desc1", actualModel.Description);
Assert.AreEqual(1, actualModel.DictionaryEntryId);
}
To test WebForms events we need to make a lot of changes and assumptions: we need to make the methods public, we need to initialize Form and its controls. It results in heavy hard-read tests which are impossible for 3) TDD.
2. Enable full control over the rendered HTML
I think this statement is a little bit exaggeration. Only HTML can give full control over rendered HTML. As for HtmlHelpers, DisplayTemplates and EditorTemplates, though the team made major improvements over 6 versions of the framework, it's still sometimes annoying to transform additionalViewData into html attributes.
For example, to pass some html attributes to an input you can't use @Html.EditorFor, you'll have to use @Html.TextBoxFor.
In the same time in ASP.NET you can specify any attributes on any elements and they will just render.
MVC:
Wrong:
@Html.EditorFor(m => m.Name, new { MySuperCustomAttribute = "Hello" })
Correct:
@Html.TextBoxFor(m => m.Name, new { MySuperCustomAttribute = "Hello" })
ASP.NET:
<asp:TextBox runat="server" ID="RecordName" MySuperCustomAttribute="hello"></asp:TextBox>
3. Enable Test Driven Development (TDD)
I think this statement is about testing of Controller vs Code-Behind. I covered this in 1.
4. No ViewState and PostBack events
ViewBag and ViewData are weak-typed facilities to pass data between Controller and Views. They are rendered as elements, nothing similar to ViewState. For example, in my View I initialize ViewBag.Title = "EditView"; which allows me to use this string on the Layout Page: <title>@ViewBag.Title - My ASP.NET MVC Application</title>. On the page it looks just like this <title>EditView - My ASP.NET MVC Application</title>
As to TempData, Session and Application, they are stored on server side. It's not rendered to page at all.
5. Easy integration with JQuery
I don't see how integration with JQuery becomes easier for MVC. Here is how we integrate JQuery into WebForms:
<script src="Scripts/jquery-1.8.2.min.js"></script>
<script>
$(document).ready(function () {
$('#DicValue').change(function () {
$('#ChosenValue').text($('#DicValue option:selected').val());
});
});
</script>
And here is almost the same snippet for ASP.NET MVC:
@section scripts{
<script src="~/Scripts/jquery-1.8.2.min.js"></script>
<script>
$(document).ready(function () {
$('#DictionaryEntryId').change(function () {
$('#ChosenValue').text($('#DictionaryEntryId option:selected').val());
});
});
</script>
}
There is another point to mention about JQuery here: as ASP.NET MVC is pretty Opinionated framework, it becomes somewhat restrictive for extensive JS usage. It was originally designed for Scaffold Templates based development, and it is best with it. JQuery is good for ajax requests and for some minor logic in ASP.NET MVC, but when you start using it extensively, you end up with two controllers for every view: a C# one and a JS one. Hello, Unit Testing! Also JQuery(UI) is very good with its rich set of UI controls.
ASP.NET is designed with Postbacks in mind and they dictate you the basic application model. However, there are also different UI Toolkits for ASP.NET to make an application more dynamic and there is still some place for JQuery.
Wow, that was a long answer. Hope it'll help.
