ORM, MVC, and Client Requests

Object-Relational Mapping (ORM)

• ORM maps database tables to PHP classes and objects.
• It allows interaction with the database using methods and properties of objects.
• ORM eliminates the need to write raw SQL queries.

Model-View-Controller (MVC)

• MVC divides the application into three components: Model, View, and Controller.
• The Model handles the data and business logic.
• The View manages the user interface and presentation of data.
• The Controller handles user requests and updates the Model and View.

Specifying Resources in Client Requests

• Clients specify resources using a Uniform Resource Identifier (URI) or Uniform Resource Locator (URL).
• The URL includes the scheme (protocol), host (server address), and path.
• The path pinpoints the exact resource, such as /users/123.
• HTTP methods (GET, POST, PUT) indicate the action to perform on the resource.
• Optional query parameters or headers (like Accept) further refine the request.

Specifying Resources and CRUD Actions

• Clients specify the resource and CRUD action using a combination of the HTTP method and the URI.
• HTTP methods indicate the CRUD action: GET (Read), POST (Create), PUT (Update), DELETE (Delete).
• The URI specifies the resource to interact with, such as /users/123.
• POST /users creates a new user
• GET /users/123 retrieves the details of user 123.

spl_autoload_register() Function

• The spl_autoload_register() function registers autoloaders.
• It enables automatic loading of classes and interfaces that are not currently defined.
• This gives PHP a last chance to load the class or interface before failing with an error.

Single Access Point in MVC

• MVC implementations typically use a single access point for handling requests.
• Routing systems or front controllers direct requests to the appropriate controller action based on the URL.
• The controller processes the request, retrieves or modifies data, and selects a view to render the response.
• Centralized handling ensures better organization and separation of concerns.

MVC Architecture Compliance

• The MVC implementation with SQL, PHP, and HTML follows the three-tier architecture.
• Presentation Layer (View) uses HTML, CSS, and JavaScript for the user interface.
• Application Layer (Controller) in PHP handles user requests and manages communication between the View and the Model.
• Data Layer (Model) manages database interactions with SQL and PHP.
• This improves scalability, maintainability, and security.

Loading Employees List on a Web Page Using MVC

• Client Makes a Request (URL & HTTP Request)
  • The client enters a URL (e.g., /employees) and sends an HTTP GET request to the server.
• Routing System (Directing the Request)
  • The web framework maps the URL to the appropriate controller action (e.g., EmployeeController#index).
• Controller Action (Processing the Request)
  • The EmployeeController is invoked to handle the request, interacting with the model to retrieve data.
• Model (Retrieving the Data)
  • The Employee Model communicates with the database to fetch data.
• Controller Passes Data to the View
  • The controller passes the retrieved data (list of employees) to a view.
• View (Rendering the Response)
  • The view generates the HTML to display the list of employees, populating a template with the employee data.
• HTTP Response (Sending the Data to the Client)
  • The HTTP response, including the generated HTML, is sent back to the client.
• Client Renders the Page
  • The client (browser) receives the HTTP response and renders the HTML content, displaying the list of employees on the web page.