How to use Python Flask RESTful

1. RESTful Overview

REST (Representational State Transfer) style is a resource-oriented Web application design style. It follows some design principles to make Web applications highly readable and user-friendly. Scalability and maintainability. Let’s explain each aspect of RESTful style in detail:

• Resource Identifier: In RESTful style, each resource has a unique identifier, Usually a URL (Uniform Resource Locator) . A URL is used to identify the location of a resource so that clients can access it using the HTTP protocol. For example, a simple URL can be: http://example.com/products/123, where "products" represents the resource type and "123" Represents a resource identifier.

• Presentation layer: Resources can be represented in different formats, such as JSON, XML, HTML wait. Clients can choose the appropriate representation to interact with as needed. For example, a RESTful API can return data in JSON format so that clients can more easily parse and process the data.

• Self-describing messages: Each message should contain enough information to describe how to handle the message. For example, an HTTP response should contain information such as status code, response headers, and response body so that the client can understand the meaning of the response.

• Stateless Communication: RESTful style design emphasizes stateless communication, which means that each request should contain all necessary information to handle the request without relying on previous requests. This can make web applications simpler and scalable because the server does not need to retain any state information.

• Uniform interface: All resources should be accessed through the same interface. This means that the client can use the same HTTP method (such as GET, POST, PUT, DELETE, etc.) to operate different types H. This makes the API simpler and more consistent, and easier for other developers to understand and use.

In short, RESTful style design makes web applications more flexible, scalable and easier to maintain, and is a modern way of designing web applications.

2. RESTful in Python

Python can be used to implement RESTful-style web applications, usually using some web frameworks to simplify the development process. The following are some common Python web frameworks:

• Flask: Flask is a simple, lightweight web framework that can be used Build RESTful web applications. It uses Python's decorator syntax to define HTTP routes, making writing web applications simple and intuitive. Flask also provides an extension mechanism so that developers can easily add new features, such as database access, form validation, etc.

• Django: Django is a powerful and comprehensive web framework that can be used to build complex web applications. It provides many built-in features such as ORM (Object Relational Mapping), form validation, authentication, etc. that enable developers to build web applications faster. Django also supports RESTful style web application development, which can be implemented using third-party libraries Django REST framework.

• Bottle: Bottle is a lightweight Web framework that uses Python's decorator syntax to define HTTP routes, which can quickly Build RESTful web applications. Bottle also includes some useful features such as template engine, database access, static file processing, etc.

• Pyramid：Pyramid is a flexible, highly customizable web framework that can be used to build various types of web applications. Includes RESTful web applications. Pyramid provides many extension mechanisms that allow developers to easily add new functionality, such as database access, form validation, authentication, etc.

The above frameworks all support RESTful style Web application development, and all have their own advantages and disadvantages. Developers can choose the appropriate framework according to their own needs.

3. Flask RESTful API example explanation

1) Flask-RESTful library explanation

Flask-RESTful is a Flask-based extension library that provides some convenient tools to build RESTful APIs. The following are some of the main features and functions of Flask-RESTful:

• Resource Class: Flask-RESTful provides a Resource base class that can be used to create resources. The Resource class contains the processing logic of HTTP methods (GET, POST, PUT, DELETE, etc.) and provides some convenient Methods to handle requests and responses.

• Request parameter parsing: Flask-RESTful provides a RequestParser class for parsing request parameters. RequestParser can automatically parse query parameters, form parameters, JSON parameters, etc. into Python types, and provides some options to specify parameter types, default values, must exist and other restrictions.

• Response formatting: Flask-RESTful provides a marshal_with() decorator for formatting response data. marshal_with() The decorator can convert Python objects into specified output formats (such as JSON, XML, etc.), and supports functions such as specifying output fields, field types, nested fields, etc.

• Route definition: Flask-RESTful provides an Api class for defining the mapping relationship between routes and resources. The Api class contains the add_resource() method, which is used to bind resource classes and URL routing.

• Exception handling: Flask-RESTful provides some exception classes for handling errors in HTTP requests and responses. The exception classes of Flask-RESTful include abort, HTTPException, etc., which can easily handle HTTP status code, error message, etc.

To sum up, Flask-RESTful provides some convenient tools to simplify the development of RESTful API. Using Flask-RESTful, you can quickly define resources, parse request parameters, format response data, define routes, handle exceptions, etc., thereby improving development efficiency and reducing the risk of errors.

2) Flask-RESTful library installation

To install the Flask-RESTful library, you can use the pip command to install it. Execute the following command in the terminal:

pip3 install flask-restful

This will download the Flask-RESTful library from PyPI and install it into the local Python environment. After the installation is complete, you can import the flask_restful module in your code and use the functions provided by Flask-RESTful to build a RESTful API.

3) RESTful example explanation

The following is a simple Flask RESTful API example, which implements a simple To-Do List application:

from flask import Flask, request
from flask_restful import Api, Resource, reqparse, fields, marshal_with
app = Flask(__name__)
api = Api(app)
todos = {}
todo_fields = {
    'id': fields.Integer,
    'task': fields.String,
    'status': fields.Boolean
}
class TodoList(Resource):
    @marshal_with(todo_fields)
    def get(self):
        return todos
    @marshal_with(todo_fields)
    def post(self):
        parser = reqparse.RequestParser()
        parser.add_argument('task', type=str, help='Task is required', required=True)
        args = parser.parse_args()
        todo_id = len(todos) + 1
        todo = {'task': args['task'], 'status': False}
        todos[todo_id] = todo
        return todo, 201
class TodoItem(Resource):
    @marshal_with(todo_fields)
    def get(self, todo_id):
        return todos[todo_id]
    def put(self, todo_id):
        parser = reqparse.RequestParser()
        parser.add_argument('task', type=str)
        parser.add_argument('status', type=bool)
        args = parser.parse_args()
        todo = todos[todo_id]
        if args['task']:
            todo['task'] = args['task']
        if args['status']:
            todo['status'] = args['status']
        return todo
    def delete(self, todo_id):
        del todos[todo_id]
        return '', 204
api.add_resource(TodoList, '/todos')
api.add_resource(TodoItem, &#39;/todos/<int:todo_id>&#39;)
if __name__ == &#39;__main__&#39;:
    app.run(debug=True)

Startup

# 配置环境变量
export FLASK_APP=restful-test.py
# 启动服务，公开访问需要加上--host=0.0.0.0
python -m flask run --host=0.0.0.0

This example uses Flask and the Flask-RESTful library to implement a RESTful API for a To-Do List application. Here is an explanation of some important code snippets:

• Define resources: In the example, there are two resources: TodoList and TodoItem. TodoList is used to process all To-Do task lists, TodoItem is used to process a single task.

• Define request parameters: In the example, we use the RequestParser of the Flask-RESTful library to parse the request parameters. We define the 'task' and 'status' parameters and use the add_argument() method to specify their types and other constraints.

• Defining the response format: In the example, we use the marshal_with() decorator of the Flask-RESTful library to define the format of the response. We define a dictionary named todo_fields, which contains the id, task and status fields of the To-Do task.

• Define the request method: In the example, we use the Resource class of the Flask-RESTful library to define the request method. We have implemented the GET, POST, PUT and DELETE methods for getting the task list, Add task, Update task and Delete task.

• Add route: In the example, we use the Api class of the Flask-RESTful library to add the route. We use the add_resource() method to bind the TodoList and TodoItem classes with the corresponding URL routes.

After running the example, you can use the To-Do List application's RESTful API by accessing the URL. For example, to get a list of all tasks , you can use the following URL:

# GET http://localhost:5000/todos
curl http://localhost:5000/todos

To add a new task , you can use the following URL:

# POST http://localhost:5000/todos
curl -XPOST http://localhost:5000/todos -d 'task=123'
curl -XPOST http://localhost:5000/todos -d '{"task":"456"}'  --header "Content-Type: application/json"

To get a single task , you can use the following URL:

# GET http://localhost:5000/todos/1
curl http://localhost:5000/todos/1

To update a task , you can use the following URL:

# PUT http://localhost:5000/todos/1
curl -XPUT http://localhost:5000/todos/1 -d '{"task":"test"}'  --header "Content-Type: application/json"
# 查看
curl http://localhost:5000/todos/1

To delete For task , you can use the following URL:

# DELETE http://localhost:5000/todos/1
curl -XDELETE http://localhost:5000/todos/1

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