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Part 51 - Advantages of using strongly typed views

Suggested Videos 
Part 48 - Custom html helpers in mvc
Part 49 - Html encoding in asp.net mvc
Part 50 - Detect errors in views at compile time

There are several ways available to pass data from a controller to a view in an mvc application. 
1. ViewBag or ViewData
2. Dynamic type
3. Strongly typed view



The following are the advantages of using strongly typed views. We get
1. Intellisense and
2. Compile-time error checking

With ViewBag and Dynamic type, we don't have these advantages.



Using ViewBag: 
Notice that, the employee object is stored in ViewBag.
In HomeController.cs
public ActionResult Details(int id)
{
    SampleDBContext db = new SampleDBContext();
    Employee employee = db.Employees.Single(x => x.Id == id);
    ViewBag.EmployeeData = employee;
    return View();
}

We want to display employee FullName and Gender. Notice that, as we are typing FullName and Gender properties, we don't get intellisense. Also, if we mis-spell FullName or Gender properties, we will not get any compilation errors. We will come to know about these errors only at runtime.
In Details.cshtml View
<div class="display-label">
    @Html.DisplayName("FullName")
</div>
<div class="display-field">
    @ViewBag.EmployeeData.FullName
</div>
<div class="display-label">
    @Html.DisplayName("Gender")
</div>
<div class="display-field">
    @ViewBag.EmployeeData.Gender
</div>

Using Dynamic Type: 
In HomeController.cs
public ActionResult Details(int id)
{
    SampleDBContext db = new SampleDBContext();
    Employee employee = db.Employees.Single(x => x.Id == id);
    return View(employee);
}

In Details.cshtml View
@model dynamic
<div class="display-label">
    @Html.DisplayName("FullName")
</div>
<div class="display-field">
    @Model.FullName
</div>
<div class="display-label">
    @Html.DisplayName("Gender")
</div>
<div class="display-field">
    @Model.Gender
</div>

With dynamic type also, we don't get intellisense and compile-time error checking.

Using Strongly Typed View: No change is required in the controller action method. Make the following change to Details.cshtml view. Notice that the view is strongly typed against Employee model class. We get intellisense and if we mis-spell a property name, we get to know about it at compile time.
@model MVCDemo.Models.Employee
<div class="display-label">
    @Html.DisplayName("FullName")
</div>
<div class="display-field">
    @Model.FullName
</div>
<div class="display-label">
    @Html.DisplayName("Gender")
</div>
<div class="display-field">
    @Model.Gender
</div>

Please Note: We discussed enabling compile time error checking in views in Part 50 of the MVC tutorial.

2 comments:

  1. Please keep the slides what you are showing the videos

    ReplyDelete
  2. Hi Sir,

    Your videos and the study material are awesome. Can I request you to post some thing on Dependency injection and Unit of work.

    Many thanks again for providing such good study materials.

    ReplyDelete

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