Communication between the Controller and View is crucial in ASP.NET MVC.

• Data is sent to the View by the Controller once it has processed requests.
• User input is gathered by the View and returned to the Controller.

CRUD (Create, Read, Update, Delete) systems and other dynamic web applications are made possible by this two-way communication.

This essay will teach us:

• How to pass Controller → View data
• How to send data from View to Controller
• Various methods
• A basic example of CRUD

Everything is explained in simple beginner-friendly steps.

MVC Architecture Overview

MVC stands for:

Flow example:
Ways to Transfer Data from Controller to View: User → Controller → Model → Controller → View → User

There are four common methods.

1 Passing Data Using ViewBag

ViewBag is a dynamic property used to pass small data.
Controller
public ActionResult Index()
{
    ViewBag.Name = "Scott";
    ViewBag.City = "London";

    return View();
}

View
<h2>Name: @ViewBag.Name</h2>
<h2>City: @ViewBag.City</h2>

What is this?
Output
Name: Scott City: London

When to Use?

• Small data
• Simple messages

2 Passing Data Using ViewData
ViewData works like a dictionary.
Controller
public ActionResult Index()
{
    ViewData["Course"] = "ASP.NET MVC";
    return View();
}

View
<h2>@ViewData["Course"]</h2>

What is this?
3 Passing Data Using TempData
TempData stores data until the next request.

Controller
public ActionResult Index()
{
    TempData["Message"] = "Record Saved Successfully";
    return RedirectToAction("Display");
}

public ActionResult Display()
{
    return View();
}

View
<h2>@TempData["Message"]</h2>

What is this?
4 Passing Data Using Model (Best Method)
This is the most recommended approach.

Step 1 Create Model
public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }
}

Step 2 Controller
public ActionResult Details()
{
    Student s = new Student()
    {
        Id = 1,
        Name = "Scott",
        Age = 22
    };

    return View(s);
}

Step 3 View
@model Student

<h2>ID: @Model.Id</h2>
<h2>Name: @Model.Name</h2>
<h2>Age: @Model.Age</h2>

Passing Data From View to Controller
Now let’s see how user input goes from View → Controller.
This is done using HTML forms.

Simple CRUD Example
We will build a simple Student CRUD system.

Step 1 Model
public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }
}

Step 2 Controller
public class StudentController : Controller
{
    static List<Student> students = new List<Student>();

    public ActionResult Index()
    {
        return View(students);
    }

    public ActionResult Create()
    {
        return View();
    }

    [HttpPost]
    public ActionResult Create(Student s)
    {
        students.Add(s);
        return RedirectToAction("Index");
    }
}

Step 3 Create View
@model Student

@using (Html.BeginForm())
{
    <label>Name</label>
    @Html.TextBoxFor(m => m.Name)

    <br/>

    <label>Age</label>
    @Html.TextBoxFor(m => m.Age)

    <br/>

    <input type="submit" value="Save"/>
}

Here the form sends data to the controller.

Step 4 Display Data
View
@model List<Student>

<table border="1">
<tr>
    <th>ID</th>
    <th>Name</th>
    <th>Age</th>
</tr>

@foreach(var item in Model)
{
<tr>
    <td>@item.Id</td>
    <td>@item.Name</td>
    <td>@item.Age</td>
</tr>
}
</table>

Flow of Data in CRUD
User enters data in View ↓ Form submits to Controller ↓ Controller receives Model ↓ Data saved ↓ Controller sends updated data to View ↓ View displays result

Important Concepts
Model Binding
Model binding automatically converts form values into model objects.

Example:
Name → Student.Name
Age → Student.Age

MVC automatically maps them.

Best Practice for Beginners
Always prefer Model-based data passing instead of ViewBag or ViewData.

Example:
Good
return View(student);

Not recommended
ViewBag.Name = "Peter";

Quick Comparison

Conclusion
Passing data between Controller and View is one of the most important concepts in ASP.NET MVC development.
Developers can use:

• ViewBag
• ViewData
• TempData
• Models

However, for real-world applications and CRUD operations, the Model approach is the most powerful and recommended method.