Overview
This lecture explains the Model-View-Controller (MVC) pattern in web development and how it separates code responsibilities to make complex applications easier to manage.
Evolution of Websites & Need for Patterns
- Websites have evolved from simple HTML/CSS pages to complex applications with thousands of developers.
- Patterns help organize code to reduce complexity and make maintenance easier.
- The most popular architectural pattern is MVC (Model-View-Controller).
MVC Pattern Overview
- MVC divides applications into three sections: Model, View, and Controller.
- Each section has a specific purpose and only interacts with the Controller, not directly with each other.
Controller Responsibilities
- The Controller receives user requests and decides how to handle them.
- It acts as a middleman, delegating data operations to the Model and presentation tasks to the View.
- The Controller should contain minimal logic and not directly handle data or presentation.
Model Responsibilities
- The Model manages all data logic, including database interactions, validation, and CRUD (Create, Read, Update, Delete) operations.
- It does not handle user requests or presentation logic.
- The Model returns data or errors to the Controller.
View Responsibilities
- The View handles how information is presented to the user, usually as dynamic HTML templates.
- It only receives data from the Controller and presents it accordingly.
- The View does not manage data or user requests.
Example: Handling a User Request (Cats List)
- User requests a list of cats; the Controller handling cats receives the request.
- The Controller asks the Cat Model for data; the Model queries the database and returns a list or an error.
- If successful, the Controller sends the list to the Cat View to be rendered in HTML.
- If an error occurs, the Controller sends the error to an Error View for presentation.
- The Controller returns the final output to the user.
Key Terms & Definitions
- MVC (Model-View-Controller) — A pattern that separates data (Model), presentation (View), and logic (Controller) in an application.
- Model — Handles all data logic and database interactions.
- View — Handles the display and presentation of information.
- Controller — Manages requests and coordinates between Model and View.
Action Items / Next Steps
- Watch the next video for the basic setup of the library application and deployment instructions.