Passing data from Controller to View in ASP.NET MVC

ASP.NET MVC is a framework that facilitates building web applications based on MVC (Model-View-Controller) design pattern. Request coming from client reaches the Controller through URL Rewriting Module. Controller decides which model to use in order to fulfill the request. Further passing the Model data to View which then transforms the Model data and renders response to client as shown in following basic level request flow diagram.

In this ASP.NET MVC Tutorial, we will discuss and implement different options to pass data from ASP.NET MVC Controller to View.

Let's begin by answering a simple ASP.NET MVC Question

You are working as ASP.NET MVC developer at WebDevTutorials and developing a library that supports multiple ASP.NET MVC web applications on a shared server. This library provides implementations of security algorithms. If a problem with any of the security algorithms is discovered, a newer version of the library must be created and deployed. Application downtime during the update must be minimized. As a responsible developer, you need to ensure that the new version of the library will be used by all applications as soon as possible. What should you do?

A. Build the web applications and include the security assembly as an embedded resource. When an update is needed, copy the new assembly to the bin directory for the application.
B. Install the security assembly in the Global Assembly Cache (GAC). When an update is needed, update the assembly in the GAC.
C. Build the security assembly as a netmodule in a shared location. Use the assembly linker to merge the netmodule into the assemblies for the application. When an update is needed, update the netmodule in the shared location.
D. Sign all assemblies in each application with the same key used to sign the security assembly. When an update is needed, create a new key pair and re-sign all assemblies.

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Correct Answers: B

Following are the different available options to pass data from a Controller to View in ASP.NET MVC along with Introduction and Background:

Let’s discuss all these options step by step in this series.

Introduction

If we want to maintain state between a Controller and corresponding View– ViewData and ViewBag are the available options but both of these options are limited to a single server call (meaning it’s value will be null if a redirect occurs). But if we need to maintain state from one Controller to another (redirect case), then TempData is the other available option.

It’s common that initially it might be a bit difficult for a ASP.NET WebForms developer to digest above flow and need for options to pass data from Controller to View. Because in WebForms approach, Controller and View are tightly coupled to each other. Please follow the link for a detailed comparison of the differences between ASP.NET WebForms and ASP.NET MVC here.

For the purpose of implementation, we will take earlier ASP.NET MVC tutorial on this blog as base and implement with different options. If you haven’t gone through the article, please read “Building your first ASP.NET MVC application in 4 simple steps” first.

ViewBag Example

As we discussed earlier that ViewBag and ViewData serves the same purpose but ViewBag is basically a dynamic property (a new C# 4.0 feature) having advantage that it doesn’t have typecasting and null checks.
So, In order to pass data from Controller to View using ViewBag, we will modify our EmployeeController code as follows:

public class EmployeeController : Controller
{
// GET: /Employee/
public ActionResult Index()
{
ViewBag.EmployeeName = “Muhammad Hamza”;
ViewBag.Company = “Web Development Company”;
ViewBag.Address = “Dubai, United Arab Emirates”;

return View();
}
}

And to get Employee details passed from Controller using ViewBag, View code will be as follows:

<body>
<div>
<h1>Employee (ViewBag Data Example)</h1>
<div>
<b>Employee Name:</b> @ViewBag.EmployeeName<br />
<b>Company Name:</b> @ViewBag.Company<br />
<b>Address:</b> @ViewBag.Address<br />
</div>
</div>
</body>

In order to see the above changes in action run the solution, we will find the following output.

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ViewData Example

As compared to ViewBag, ViewData is a dictionary object which requires typecasting as well as null checks. Same above implementation using ViewData can be achieved as follows:

public class EmployeeController : Controller
{
// GET: /Employee/
public ActionResult Index()
{
ViewData[“EmployeeName”] = “Muhammad Hamza”;
ViewData[“Company”] = “Web Development Company”;
ViewData[“Address”] = “Dubai, United Arab Emirates”;

return View();
}
}

And to get Employee details passed from Controller using ViewBag, View code will be as follows:

<body>
<div>
<h1>Employee (ViewBag Data Example)</h1>
<div>
<b>Employee Name:</b> @ViewData[“EmployeeName”]<br />
<b>Company Name:</b> @ViewData[“Company”]<br />
<b>Address:</b> @ViewData[“Address”]<br />
</div>
</div>
</body>

Run the application to view the following output.

Hopefully, this ASP.NET MVC Tutorial will provide reader with a better understanding of passing data from Controller to View in ASP.NET MVC using ViewBag and ViewData. Please follow the link for detailed understanding about Using TempData in ASP.NET MVC.

Let’s test your ASP.NET MVC Skill.

Please choose the correct statements about ViewBag and ViewData [Choose Two]?

A. ViewData is a Dictionary object and it requires typecasting while getting data.
B. ViewData is a Dynamic Property so it doesn’t require typecasting for getting data.
C. ViewBag is a Dictionary object and it requires typecasting while getting data.
D. ViewBag is a Dynamic Property so it doesn’t require typecasting for getting data.