ASP.NET Core MVC Fundamentals

Level: Intermediate

ℹ️ What You'll Learn

• MVC pattern: Model (data objects), View (HTML templates), Controller (request handlers)
• Request flow: Browser → Controller action → gets Model data → passes to View → View renders HTML
• Controller: Class handling HTTP requests (StudentsController, TeachersController)
• Controller base class: public class StudentsController : Controller (includes View(), RedirectToAction(), etc.)
• Action methods: public IActionResult Index() handles HTTP request, returns HTML response
• View (.cshtml): HTML template mixing C# and HTML (@model List<Student>, @foreach (var s in Model))
• Model: Data passed from Controller to View (return View(students) passes student list)
• Model binding: Form data automatically converts to model (Create(Student student) populated from POST form)
• Tag helpers: <input asp-for="Name"> generates form fields bound to model properties
• Routing: URL maps to Controller action (/students/details/5 → StudentsController.Details(id: 5))
• ViewData/ViewBag: Flexible data passing Controller → View (ViewData["Title"] = "Students")
• School Management pages: StudentList (Index), StudentDetails, CreateStudent, EditStudent
• HTML form submission: POST to action, action validates, returns View with errors or redirects to success page
• CRUD workflow: Index (list) → Create (form) → POST Create (save) → Redirect → Details (view)

What is MVC?

Model-View-Controller architectural pattern.

• Model = Data (Student, Exam, Fee)
• View = HTML UI (Razor .cshtml files)
• Controller = Request handler, business logic

User Request → Controller → Model → View → HTML Response

Project Structure

SMS.Web/
├── Controllers/
│   ├── StudentsController.cs
│   ├── ExamsController.cs
│   └── FeesController.cs
├── Views/
│   ├── Students/
│   │   ├── Index.cshtml
│   │   ├── Details.cshtml
│   │   ├── Create.cshtml
│   │   └── Edit.cshtml
│   ├── Shared/
│   │   ├── _Layout.cshtml
│   │   └── _ValidationScriptsPartial.cshtml
│   └── Home/
│       └── Index.cshtml
├── Models/
│   ├── Student.cs
│   ├── Exam.cs
│   └── ViewModels/
│       └── StudentViewModel.cs
├── Program.cs
└── appsettings.json

Controllers and Actions

Controller = class handling HTTP requests. Action = public method returning view or data.

using Microsoft.AspNetCore.Mvc;

public class StudentsController : Controller
{
    private readonly IStudentService _service;

    public StudentsController(IStudentService service)
    {
        _service = service;
    }

    // GET: /students
    public async Task<IActionResult> Index()
    {
        var students = await _service.GetStudentsAsync();
        return View(students);
    }

    // GET: /students/5
    public async Task<IActionResult> Details(int id)
    {
        var student = await _service.GetStudentAsync(id);
        if (student == null)
            return NotFound();

        return View(student);
    }

    // GET: /students/create
    public IActionResult Create()
    {
        return View();
    }

    // POST: /students/create
    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> Create(Student student)
    {
        if (ModelState.IsValid)
        {
            await _service.CreateStudentAsync(student);
            return RedirectToAction(nameof(Details), new { id = student.Id });
        }

        return View(student);
    }

    // GET: /students/edit/5
    public async Task<IActionResult> Edit(int id)
    {
        var student = await _service.GetStudentAsync(id);
        if (student == null)
            return NotFound();

        return View(student);
    }

    // POST: /students/edit/5
    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> Edit(int id, Student student)
    {
        if (id != student.Id)
            return NotFound();

        if (ModelState.IsValid)
        {
            await _service.UpdateStudentAsync(id, student);
            return RedirectToAction(nameof(Index));
        }

        return View(student);
    }

    // POST: /students/delete/5
    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> Delete(int id)
    {
        await _service.DeleteStudentAsync(id);
        return RedirectToAction(nameof(Index));
    }
}

Views and Razor Syntax

View = Razor .cshtml file. Mix C# and HTML.

File: Views/Students/Index.cshtml

@model List<Student>

@{
    ViewData["Title"] = "Students";
}

<h1>Students List</h1>

<a class="btn btn-primary" asp-action="Create">Add Student</a>

<table class="table">
    <thead>
        <tr>
            <th>Name</th>
            <th>Roll Number</th>
            <th>Class</th>
            <th>Status</th>
            <th>Actions</th>
        </tr>
    </thead>
    <tbody>
        @foreach (var student in Model)
        {
            <tr>
                <td>@student.Name</td>
                <td>@student.RollNumber</td>
                <td>@student.ClassName</td>
                <td>@student.Status</td>
                <td>
                    <a asp-action="Details" asp-route-id="@student.Id">View</a>
                    <a asp-action="Edit" asp-route-id="@student.Id">Edit</a>
                    <form asp-action="Delete" asp-route-id="@student.Id" method="post" style="display:inline;">
                        <button type="submit" onclick="return confirm('Are you sure?');">Delete</button>
                    </form>
                </td>
            </tr>
        }
    </tbody>
</table>

Model Binding from Forms

Forms automatically bind to model properties.

File: Views/Students/Create.cshtml

@model Student

@{
    ViewData["Title"] = "Create Student";
}

<h1>Add New Student</h1>

<form asp-action="Create" method="post">
    <div class="form-group">
        <label asp-for="Name"></label>
        <input asp-for="Name" class="form-control" />
        <span asp-validation-for="Name" class="text-danger"></span>
    </div>

    <div class="form-group">
        <label asp-for="RollNumber"></label>
        <input asp-for="RollNumber" class="form-control" />
        <span asp-validation-for="RollNumber" class="text-danger"></span>
    </div>

    <div class="form-group">
        <label asp-for="ClassName"></label>
        <select asp-for="ClassName" class="form-control">
            <option value="">Select Class</option>
            <option value="10-A">10-A</option>
            <option value="10-B">10-B</option>
            <option value="11-A">11-A</option>
        </select>
        <span asp-validation-for="ClassName" class="text-danger"></span>
    </div>

    <div class="form-group">
        <label asp-for="Status"></label>
        <select asp-for="Status" class="form-control">
            <option value="Active">Active</option>
            <option value="Inactive">Inactive</option>
        </select>
    </div>

    <button type="submit" class="btn btn-primary">Create</button>
    <a asp-action="Index" class="btn btn-secondary">Cancel</a>
</form>

@section Scripts {
    @{
        await Html.RenderPartialAsync("_ValidationScriptsPartial");
    }
}

POST binds form values to Student model automatically.

Tag Helpers

Replace HTML with smart tags. Generate correct URLs automatically.

Tag Helper	Purpose
asp-action	Action method name
asp-controller	Controller name
asp-route-id	Route parameter value
asp-for	Property binding (label, input)
asp-validation-for	Validation error message

Layout and Shared Views

File: Views/Shared/_Layout.cshtml

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <title>@ViewData["Title"] - SMS</title>
    <link rel="stylesheet" href="~/lib/bootstrap/css/bootstrap.min.css" />
</head>
<body>
    <nav class="navbar navbar-expand-sm navbar-toggleable-sm navbar-light bg-white border-bottom box-shadow mb-3">
        <div class="container-fluid">
            <a class="navbar-brand" asp-controller="Home" asp-action="Index">SMS</a>
            <button class="navbar-toggler" type="button">
                <span class="navbar-toggler-icon"></span>
            </button>
            <div class="navbar-collapse collapse">
                <ul class="navbar-nav flex-grow-1">
                    <li class="nav-item">
                        <a class="nav-link text-dark" asp-controller="Students" asp-action="Index">Students</a>
                    </li>
                    <li class="nav-item">
                        <a class="nav-link text-dark" asp-controller="Exams" asp-action="Index">Exams</a>
                    </li>
                </ul>
            </div>
        </div>
    </nav>

    <div class="container">
        <main role="main" class="pb-3">
            @RenderBody()
        </main>
    </div>

    <script src="~/lib/jquery/jquery.min.js"></script>
    <script src="~/lib/bootstrap/js/bootstrap.min.js"></script>
</body>
</html>

In other views: @{ Layout = "_Layout"; }

Program.cs Setup

var builder = WebApplicationBuilder.CreateBuilder(args);

// Add MVC
builder.Services.AddControllersWithViews();

// Services
builder.Services.AddScoped<IStudentService, StudentService>();

var app = builder.Build();

if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Home/Error");
}

app.UseStaticFiles();
app.UseRouting();

app.MapControllerRoute(
    name: "default",
    pattern: "{controller=Home}/{action=Index}/{id?}"
);

app.Run();

Routing

Default route: {controller}/{action}/{id?}

Examples:

• /students → StudentsController.Index()
• /students/details/5 → StudentsController.Details(id=5)
• /students/edit/5 → StudentsController.Edit(id=5)

Key Takeaways

• MVC = separate concerns (Model, View, Controller)
• Controllers = handle requests and orchestrate
• Views = Razor templates with C# expressions
• Model binding = automatic form-to-object conversion
• Tag helpers = generate proper HTML and URLs
• Layout = shared header, nav, footer

💡 MVC Tip

Keep business logic in services, not controllers. Controllers orchestrate only.

🤖Use AI to Learn Faster

Use ChatGPT, Claude, or Copilot to go deeper on ASP.NET Core MVC Fundamentals. Try these prompts:

• "What's the difference between MVC and Web API?"
• "How does model binding work?"
• "What are tag helpers?"
• "When should I use partials vs layouts?"
• "Quiz me on ASP.NET Core MVC"

💡 Tip: After reading this article, paste your own code into AI and ask "What could go wrong here and why?" — fastest way to find edge cases and deepen understanding.