ASP.NET

Session04 Notes

3 min read

Session 4: Views, Razor Syntax, Bootstrap, and Helpers

📝 Overview

In this session, we covered the following concepts:

  • Creating and Organizing Views in MVC
  • Razor Syntax for dynamic content rendering
  • Bootstrap integration for responsive UI
  • Using Tag Helpers and HTML Helpers
  • View Components
  • ViewImports and ViewStart
  • ViewData vs ViewBag
  • OOP Concepts in MVC: Encapsulation, Inheritance, Polymorphism, Abstraction, DTO

📚 Topics Covered

✅ Creating and Organizing Views

Learn how views are structured in ASP.NET Core MVC, how to use layouts and partials.

✅ Razor Syntax

Use C# inside HTML with Razor to build dynamic views
⭐ Razor Docs

✅ Bootstrap

Integrate responsive design into your app using Bootstrap
⭐ Bootstrap W3Schools

✅ Tag Helpers and HTML Helpers

Tools to simplify HTML generation in Razor views

📌 Notes

Collected from various sources including Microsoft Learn, W3Schools, and ChatGPT

Part 1: Introduction to Views

  • Views (.cshtml files) are templates that render HTML with Razor syntax.
  • Views are organized in Views/ControllerName/ViewName.cshtml.
  • The View() method in a controller renders the corresponding view.
  • Layouts (_Layout.cshtml) allow reuse of common HTML structure like headers/footers.
  • Partial Views help modularize repeated sections (like a profile box).

Part 2: Razor Syntax

  • Use @ to enter C# in HTML.
  • Implicit: @Model.Name, Explicit: @(Model.Name + "!")
  • Code blocks: @{ var msg = "Hello"; }
  • Loops and conditionals are supported: @if, @for, @foreach, @switch
  • Razor supports local functions in code blocks for reusability

Part 3: Bootstrap

  • Bootstrap helps in building responsive UI components.
  • Grid system, forms, buttons, navbars, modals etc. are supported.
  • Integration involves adding Bootstrap CSS/JS in layout or view.

Part 4: Tag Helpers and HTML Helpers

Tag Helpers:

  • Looks like HTML with asp-* attributes
  • Example: <a asp-controller="Home" asp-action="About">Link</a>
  • Requires @addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers in _ViewImports.cshtml

HTML Helpers:

  • Use C# syntax like @Html.TextBoxFor(...), @Html.BeginForm()
  • More verbose but offers fine control with C# expressions

Comparison:

FeatureTag HelpersHTML Helpers
SyntaxHTML-likeC# methods
ReadabilityHighModerate
Useasp-*@Html.*

Part 5: View Components

  • View components are reusable UI elements with server-side logic.
  • Similar to partial views but support code execution (e.g., DB queries).
  • Suitable for dynamic parts like shopping carts or recent posts.

Part 6: ViewImports and ViewStart

  • _ViewStart.cshtml sets the layout for Razor Pages. Placing one in a folder affects all views inside it.
  • _ViewImports.cshtml adds namespaces, tag helpers, etc.
  • Hierarchical: Local files override root-level ones.

Part 7: ViewData vs ViewBag

FeatureViewDataViewBag
TypeDictionaryDynamic
AccessViewData["Key"]ViewBag.Key
Compile-time check❌❌
Shared storage✅✅
  • Use ViewBag for simpler, cleaner access; ViewData for explicit key-value access.
  • Both are weakly typed and best avoided in favor of ViewModels in large apps.

Part 8: OOP Concepts in MVC

Encapsulation

  • Use private fields with public get/set properties.
  • Prevents external access to internal data structures.

DTO (Data Transfer Object)

  • Used to carry data between layers.
  • Reduces coupling and increases control over exposed data.

Inheritance

  • Share common logic between base and derived classes.
  • Enables better reuse and organization.

Polymorphism

  • Compile-time: Method overloading.
  • Runtime: Method overriding.
  • One interface, many implementations.

Abstraction

  • Hides complex implementation from the user.
  • Achieved via abstract classes or interfaces.

🧪 Practice

  • Create a view with a layout and partial
  • Use Razor syntax to display dynamic data
  • Build a form with Tag Helpers
  • Refactor a view using HTML Helpers
  • Create and render a View Component
  • Use _ViewStart.cshtml and _ViewImports.cshtml for configuration

🙏 Acknowledgments

Sources:

Graph View

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