ASP.NET Core Tutorial - Implementing Login Functionality (Part 70)

Overview

• Focus: Implementing login functionality using the Identity API in ASP.NET Core.
• Key Components: Login View Model, Login View, Login Actions (GET and POST).

Login View Model

• Purpose: To capture user data needed for login.
• Properties:
  • Email: Username (required, email address attributes used for validation).
  • Password: User's password.
  • Remember Me: Boolean to determine whether to create a persistent or session cookie.
• Location: Place in ViewModels folder (LoginViewModel class).
• Validation Attributes: Ensure to import data annotations namespace.

Login View

• Purpose: Display login form to the user.
• Model: Uses LoginViewModel.
• Placement: Account subfolder in the Views folder (Login.cshtml file).
• Components:
  • Page Title: Set using ViewBag.Title.
  • Form elements: Email, password, remember me checkbox, and submit button.
  • Bootstrap 4: Used for styling (row, col-md-12, text-danger, form-group classes).
  • Form Submission: HTTP POST request to login the user.
• Validation Summmary: Displays any validation errors.

Login Actions in Account Controller

• GET Action: Displays the login view when /account/login is requested.
• POST Action:
  • Handles form submission.
  • Parameters: Receives LoginViewModel.
  • Steps:
    1. Check if model state is valid.
    2. If valid, use SignInManager to sign the user in (PasswordSignInAsync method).
    3. Check the result: Redirect to Home Index if successful, otherwise display error.
• SignInManager Usage:
  • Injected via constructor.
  • PasswordSignInAsync method:
    • Parameters: Username, password, isPersistent (from remember me), lockoutOnFailure.
    • Returns: SignInResult object with success status.
• Post-Login Behavior:
  • Redirect to Home Index on success.
  • Display invalid login attempt error on failure.
  • Re-render login view with validation errors if model state is invalid.

Cookies: Session vs Persistent

• Session Cookie:
  • Created if remember me is NOT checked.
  • Lost when browser is closed.
  • Example: ASP.NET Core anti-forgery cookie.
• Persistent Cookie:
  • Created if remember me is checked.
  • Saved to the machine, persists after browser is closed.
  • Removed upon logout.
• Logout Behavior:
  • Removes either type of cookie immediately.
  • Application shows Register and Login links instead of Logout.

Example Output

• Login without Remember Me: Session cookie, lost on browser close.
• Login with Remember Me: Persistent cookie, retained on browser close.
• Logout Process: Immediate removal of login cookie.

Key Code Snippets

• Login View: Code for labels, input elements, validate summary.
• Account Controller: GET and POST login actions.

Conclusion: Successfully implemented the login functionality including validation, cookie handling, and redirect logic.