MVC Architecture Analysis--Understanding the Basic Principles of Web Applications

MVC (Model-View-Controller) architecture is a software design commonly used to build Web applications model. It divides the application into three basic components: Model, View and Controller. Each part is responsible for different functions and works together to make the application clearer, maintainable and scalable.

1. Model
   The model is the core part of the application and is responsible for managing data and business logic. It represents the state and behavior of the application and is independent of views and controllers. Models typically contain code that interacts with the database, including operations such as querying, updating, and deleting data. In MVC architecture, the model does not interact directly with the user.

The following is an example of a simple model class (using Python language):

class User: def __init__(self, username, password): self.username = username self.password = password def save(self): # 数据库插入操作的代码 def delete(self): # 数据库删除操作的代码 def update(self): # 数据库更新操作的代码 @staticmethod def find(username): # 数据库查询操作的代码

2. View (View)
   The view is the presentation part of the user interface and is responsible for Display data to the user, usually an HTML page. It receives data from the controller and presents it to the user. The view does not process business logic, but is only responsible for displaying data and sending user operations to the controller.

Here is an example of a simple view (using HTML and Jinja2 template engine):

   
  
用户信息
  {% for user in users %}  {% endfor %} 
 
 
用户名
 
密码
 
 
{{ user.username }}
 
{{ user.password }}
 
  

3. Controller (Controller)
   The controller is the model and the view The middle layer between them is responsible for processing user requests and managing business logic. It receives user operations from the view, updates the model accordingly, and sends the updated data to the view for rendering. The controller is also responsible for routing requests and mapping specific URLs to corresponding handler functions.

The following is an example of a simple controller (using Python and the Flask framework):

@app.route('/users', methods=['GET']) def get_users(): users = User.find_all() return render_template('users.html', users=users) @app.route('/users', methods=['POST']) def create_user(): username = request.form['username'] password = request.form['password'] user = User(username, password) user.save() return redirect('/users') @app.route('/users/', methods=['GET']) def get_user(username): user = User.find(username) return render_template('user.html', user=user) @app.route('/users/', methods=['POST']) def update_user(username): user = User.find(username) user.username = request.form['username'] user.password = request.form['password'] user.update() return redirect('/users') @app.route('/users/', methods=['DELETE']) def delete_user(username): user = User.find(username) user.delete() return redirect('/users')

Through the above code example, we can see the basic implementation of the MVC architecture. The model is responsible for defining data operation methods, the view is responsible for presenting data to the user, and the controller operates the model according to the user's request and returns the updated data to the view.

Summary:
MVC architecture is a software design pattern for building clear, maintainable and scalable web applications. By dividing the application into three parts: model, view, and controller, each part has clear responsibilities, the application's code can be better organized and managed. At the same time, the MVC architecture also provides a good project structure and module division, making teamwork more efficient and flexible. Whether it is a small project or a large project, the MVC architecture is a very classic and practical design pattern.

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