MVC stands for Model-View-Controller, and it is a design pattern that helps organize web applications into three components: models, views, and controllers. It makes the code more modular, reusable, and maintainable.
In this post, you will learn how to use MVC in Express.js, a popular web framework for Node.js. You will also see how to create models, views, and controllers for a simple web application.
What is MVC?
MVC is a design pattern that separates the concerns of an application into three components:
- Models are responsible for managing the data of the application. They interact with databases or other sources of information, and provide an abstraction layer for the controllers. Models can also define the business logic and validation rules of the application.
- Views are responsible for presenting the data to the user. They are usually templates that generate HTML, CSS, or other output formats. Views can also include dynamic elements such as forms, buttons, or charts that interact with the user or the controllers.
- Controllers are responsible for handling the requests from the user. They receive input from the views, call the appropriate models to manipulate or retrieve data, and send the response back to the views. Controllers act as a bridge between models and views.
Models
Models manage the application's data. They handle interactions with databases, APIs, or other data sources, abstracting data access for the controllers. In addition, models can define business logic and validation rules, ensuring data integrity and consistency.
// Example Model
const UserModel = {
getById: (id) => {
// Fetch user from database
},
create: (userData) => {
// Create a new user
},
};
Views
Views are responsible for presenting data to users. They generate HTML, CSS, or other output formats, often incorporating templates. Dynamic elements like forms, buttons, and interactive charts can also be part of views, enabling user interaction.
<!-- Example View using EJS -->
<!DOCTYPE html>
<html>
<head>
<title>User Profile</title>
</head>
<body>
<h1><%= user.name %></h1>
<p><%= user.bio %></p>
</body>
</html>
Controllers
Controllers manage user requests and coordinate actions between models and views. They receive input from views, use models to manipulate or fetch data, and send the response back to views. Controllers bridge the gap between data and presentation.
// Example Controller
const UserController = {
showUserProfile: (req, res) => {
const user = UserModel.getById(req.params.userId);
res.render('userProfile', { user });
},
};
Leveraging Express.js for MVC
Express.js, a popular Node.js web framework, seamlessly supports MVC architecture. With its flexibility, Express.js simplifies server creation, route handling, middleware integration, and error management. You can also enhance its functionality using various libraries.
To implement MVC in Express.js, start by creating a structured folder hierarchy that separates models, views, and controllers. Utilize a template engine like EJS, Pug, or Handlebars for rendering views. Below is a simplified example structure:
- my-express-app/
- controllers/
- userController.js
- models/
- userModel.js
- views/
- userView.ejs
- app.js
In conclusion, adopting MVC architecture can greatly improve the organization and maintainability of your web applications. It encourages clean separation of concerns, making your codebase more robust and scalable. With the support of frameworks like Express.js, implementing MVC becomes even more seamless and effective.
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