Models

Models in MVC

Eyal Vardi
CEO E4D Solutions LTD
Microsoft MVP Visual C#
blog: www.eVardi.com

Agenda
 Integrating the Model & Controller

 Model Binders

 Model Validation

© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

What Is a Model?
Model Template
Model

Deserialization

HTML View Controller HTTP

Template


Model Attributes
 Scaffolding
 [ScaffoldColumn]

 View
 [HiddenInput]
 [Display]
 [DisplayName], Attribute on a Class
 [DataType(...)]
 [UIHint(...)]
 [AdditionalMetadata( key , value )]


Display Attribute
[DisplayName("Book")] Model
public class E4DBook
{
[Display(Name = "Title")]
public string E4DTitle { get; set; }

}
<h2>@Html.LabelForModel()</h2> View
@Html.EditorForModel()

Or

@Html.LabelFor(m => m.E4DTitle)


DataType Attribute
 DateTime  Password
 Date  Url
 Time  EmailAddress
 Text

 MultilineText


UIHint Attribute
 Use the UIHint attribute to specify the
template we want to use to render HTML for a
property.

{
[DateType(DataType.MultilineText)]
[UIHint("MultilineText")]

}


Built in View Template
 Boolean  Object
 Collection  Password
 Decimal  String
 EmailAddress  Text
 HiddenInput  Url
 Html
 MultilineText


Model Templates


What Is a Model?
Model Binding
Model

Deserialization

HTML View Controller HTTP

Template


HTTP to .NET Classes

public ActionResult Index(Reservation reservation)
{
// TODO BL.
return View( reservation );
} Deserialization


Model Binders
 Binders are like type converters, because they
can convert HTTP requests into objects that
are passed to an action method.


DefaultModelBinder Class
 Translate HTTP request into
complex models, including
nested types and arrays.
 URL
 Form data, Culture - Sensitive

1. Request.Form

2. RoutedData.Values
(Key,Value)
3. Request.QueryString

4. Request.Files


Binding to Complex Types
{

public Reservation MyReservation { get; set; }
}

@Html.LabelFor(model => model.MyReservation.FlightNum) View
@Html.EditorFor(model => model.MyReservation.FlightNum)

Html
<label for="MyReservation_FlightNum">FlightNum</label>

<input type="text" value=""
id = "MyReservation_FlightNum"
name = "MyReservation.FlightNum" />


Specifying Custom Prefixes
Controller
public ActionResult Index(
Reservation res1 ,
[Bind(Prefix="myRes")] Reservation res2 ) { ... }

<!– First Arg --> Html
<label for="FlightNum">FlightNum</label>
<input type="text" id="FlightNum" name="FlightNum" />

...

<!– Second Arg -->
<label for="MyRes_FlightNum">FlightNum</label>
<input type="text" id="MyRes_FlightNum" name="MyRes.FlightNum" />


Bind Attribute (“View”)
 Represents an attribute that is used to provide
details about how model binding to a
parameter should occur.

[Bind(Include = "FlightNum, TravelDate)]
public class Reservation
{
public int FlightNum { get; set; }
public DateTime TravelDate { get; set; }
public int TicketCount { get; set; }
public int DiscountPercent { get; set; }
}


Bind Attribute


Binding to a String Collections
Controller
public ActionResult Index( List< string > reservation ) { ... }

Html
<input type="text" name="reservation" value="…" />


Binding to a Collections
Controller
public ActionResult Index( List<Reservation> reservation ) { ... }

<!– Option I--> Html
<input type="text" name="[0].Name" />
<input type="text" name="[1].Name" />

<!– Option II -->
<input type="hidden" name="Index" value="f1" />
<input type="text" name="[f1].Name" />

<input type="hidden" name="Index" value="f2" />
<input type="text" name="[f2].Name" />


Binding to a Dictionary
Controller
public ActionResult Index( Dictionary<Reservation> reservation ) { ... }

Html
<input type="hidden" name="[0].key" value="f1" />
<input type="text" name="[0].value.Name" />

<input type="hidden" name="[1].key" value="f2" />
<input type="text" name="[1].value.Name" />


Manually Invoking Model Binding


Custom Model Binders
 ASP.NET MVC allows us to override both the
default model binder, as well as add custom
model binders.
ModelBinders.Binders.DefaultBinder = new CustomDefaultBinder();

ModelBinders.Binders.Add(
typeof(DateTime),
new DateTimeModelBinder() );


ModelBinder Attribute
 Represents an attribute that is used to
associate a model type to a model-builder
type.

public ActionResult Contact(
[ModelBinder(typeof(ContactBinder))] Contact contact )
{
ViewData["name"] = contact.Name;
ViewData["email"] = contact.Email;
ViewData["message"] = contact.Message;
ViewData["title"] = "Succes!";

return View();
}


Custom Binder


Integrating The Model & Controller
Deserialization

public ActionResult Index(Reservation reservation)
{
int totalCost = reservation.TicketCount * 100;

if (reservation.DiscountPercent != 0)
{
BL totalCost -= (totalCost * reservation.DiscountPercent / 100);
}

ViewBag.TotalCost = totalCost; Index.cshtml
@model Reservation
return View( reservation );
}
Model


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