What is MVC? Model View Controller Explained

Опубликовано: 22 Август 2024
на канале: Cameron McKenzie

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What is Model View Controller? Also known as the MVC design pattern, model-view-controller describes a way for developers to split their applications up into isolated and loosely coupled domains.

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The Model-View-Controller (MVC) is an architectural pattern used in software engineering for organizing code in a way that separates concerns. It's commonly applied in web development but also used in desktop and mobile applications. MVC divides an application into three interconnected components, allowing for modularity and clearer separation of logic and user interface.

1. Model
Purpose: The model represents the data and the business logic of the application. It directly manages the data, logic, and rules of the application.
Responsibilities:
Retrieves and manipulates data from the database.
Contains the business logic, such as calculations or data validation.
Acts as an interface between the application’s data and the user interface (UI).
Example: In a web-based e-commerce application, the Product model would represent product-related data, including attributes like price, description, and stock availability. It would handle operations like querying products from the database or calculating discounts.
2. View
Purpose: The view is responsible for presenting the data to the user. It defines how the information from the model is displayed, typically through a user interface like HTML for web apps or graphical elements for desktop/mobile apps.
Responsibilities:
Displays data from the model to the user in a presentable format.
Does not contain any business logic or direct interaction with data storage.
Renders UI elements based on the model’s state.
Example: In the e-commerce application, the view could be an HTML template that displays the product list and details to the user. This view would format the data retrieved from the Product model and render it in the browser.
3. Controller
Purpose: The controller acts as an intermediary between the model and the view. It processes user input, interacts with the model, and determines which view should be displayed.
Responsibilities:
Receives user input from the view (e.g., form submissions or button clicks).
Updates the model based on the input.
Chooses the appropriate view to display based on changes in the model or user interactions.
Example: In the e-commerce application, when a user adds a product to the shopping cart, the controller processes this action, updates the Cart model with the new product, and returns a view showing the updated cart.
How MVC Works Together
Interaction Flow:

User Interaction: The user interacts with the application through the view (e.g., clicking a button or submitting a form).
Controller Handling: The controller captures this input, processes it, and decides how to handle the action. This may involve updating the model.
Model Update: If necessary, the controller updates the model, which might involve CRUD operations or business logic processing.
View Update: The controller selects the appropriate view, which reflects the updated state of the model, and renders it back to the user.