Building Mock APIs with Swagger
Last Updated :
22 Jan, 2024
This step-by-step tutorial for constructing a mock API in Python using Swagger. In this article, we’ll step through the full process, from defining our API with Swagger to developing and testing a mock server. Whether you’re an experienced developer or just starting started, this article will show you how to construct Mock APIs with Swagger. The project entails developing basic Mock APIs with Swagger, building a mock server in Python, and testing it to replicate API behavior.
Basic Terminologies
- Swagger: An API standard with tools for designing, creating, documenting, and consuming RESTful web services.
- A mock API is a mimicked version of a genuine API that is used for testing and development.
Building Mock APIs with Swagger in Python
Using Swagger, we will build a “basic Todo API“, produce a Python server stub, implement mock server logic, and execute the application. To replicate API answers, mock data for todos will be utilized. Below is the step-by-step procedure to build mock APIs with Swagger:
Step 1: Installation
In this step, we will install all the dependencies that we will require to build Mock APIs with Swagger. These are:
Install the below dependencies using pip and the following command:
pip install flask-restful
pip install flasgger
Step 2: Project Structure
Folder Structure
|--->app.py
|--->swagger.yml
Step 3: Create Swagger Specification
The provided Swagger YAML file (swagger.yml) defines the API structure and is used by the Swagger instance to generate Swagger UI documentation for the API. In this code, a Swagger 2.0 specification defines a Todo API with CRUD operations. It includes endpoints for retrieving all todos, creating a new todo, and managing individual todos by ID through GET, PUT, and DELETE operations.
Python3
swagger: '2.0'
info:
title: Todo API
description: Simple Todo API with CRUD operations
version: '1.0'
paths:
/todos:
get:
summary: Get all todos
responses:
'200':
description: A list of todos
post:
summary: Create a new todo
parameters:
- name: todo
in: body
required: true
schema:
type: object
properties:
task:
type: string
description: The task for the new todo
completed:
type: boolean
description: Whether the task is completed
responses:
'201':
description: Todo created successfully
/todos/{todo_id}:
parameters:
- name: todo_id
in: path
required: true
type: integer
get:
summary: Get a specific todo by ID
responses:
'200':
description: Todo details
'404':
description: Todo not found
put:
summary: Update a specific todo by ID
parameters:
- name: todo
in: body
required: true
schema:
type: object
properties:
task:
type: string
description: The updated task
completed:
type: boolean
description: Whether the task is completed
responses:
'200':
description: Todo updated successfully
'404':
description: Todo not found
delete:
summary: Delete a specific todo by ID
responses:
'200':
description: Todo deleted successfully
'404':
description: Todo not found
|
Step 4: Implement Mock API Server Logic
In this Python code, a Flask application is created to implement a Todo API using Flask-Restful. The endpoints for managing todos are defined with GET, PUT, DELETE, POST methods, and Swagger is integrated for API documentation using the provided Swagger YAML template.
app.py
Python3
from flask import Flask, request
from flask_restful import Api, Resource
from flasgger import Swagger
app = Flask(__name__)
api = Api(app)
swagger = Swagger(app, template_file='swagger.yml')
todos = []
class TodoResource(Resource):
def get(self, todo_id):
todo = next((t for t in todos if t['id'] == todo_id), None)
if todo:
return todo
else:
return {'message': 'Todo not found'}, 404
def put(self, todo_id):
todo = next((t for t in todos if t['id'] == todo_id), None)
if todo:
todo['task'] = request.json.get('task', todo['task'])
todo['completed'] = request.json.get(
'completed', todo['completed'])
return {'message': 'Todo updated successfully'}
else:
return {'message': 'Todo not found'}, 404
def delete(self, todo_id):
global todos
todos = [t for t in todos if t['id'] != todo_id]
return {'message': 'Todo deleted successfully'}
class TodoListResource(Resource):
def get(self):
return {'todos': todos}
def post(self):
new_todo = {
'id': len(todos) + 1,
'task': request.json['task'],
'completed': request.json.get('completed', False)
}
todos.append(new_todo)
return {'message': 'Todo created successfully'}, 201
api.add_resource(TodoListResource, '/todos')
api.add_resource(TodoResource, '/todos/<int:todo_id>')
if __name__ == '__main__':
app.run(debug=True)
|
Step By Step Explanation of this Code
Import Necessary Modules
Import necessary modules and libraries, including Flask for the web framework, request for handling HTTP requests, Api and Resource from Flask-RESTful for building REST APIs, and Swagger from flasgger for integrating Swagger UI. Initialize the Flask app, API, and Swagger.
Python3
from flask import Flask, request
from flask_restful import Api, Resource
from flasgger import Swagger
app = Flask(__name__)
api = Api(app)
swagger = Swagger(app, template_file='swagger.yml')
todos = []
|
TodoResource Class
Define a class for handling individual todos (TodoResource). Implement methods for handling GET (retrieve todo by ID), PUT (update todo by ID), and DELETE (delete todo by ID) operations. The methods use the global todos list to store todo items.
Python3
class TodoResource(Resource):
def get(self, todo_id):
todo = next((t for t in todos if t['id'] == todo_id), None)
if todo:
return todo
else:
return {'message': 'Todo not found'}, 404
def put(self, todo_id):
todo = next((t for t in todos if t['id'] == todo_id), None)
if todo:
todo['task'] = request.json.get('task', todo['task'])
todo['completed'] = request.json.get(
'completed', todo['completed'])
return {'message': 'Todo updated successfully'}
else:
return {'message': 'Todo not found'}, 404
def delete(self, todo_id):
global todos
todos = [t for t in todos if t['id'] != todo_id]
return {'message': 'Todo deleted successfully'}
|
TodoListResource Class
Define a class for handling the list of todos (TodoListResource). Implement methods for handling GET (retrieve all todos) and POST (create a new todo) operations. The POST method adds a new todo to the todos list.
Python3
class TodoListResource(Resource):
def get(self):
return {'todos': todos}
def post(self):
new_todo = {
'id': len(todos) + 1,
'task': request.json['task'],
'completed': request.json.get('completed', False)
}
todos.append(new_todo)
return {'message': 'Todo created successfully'}, 201
|
Resource Registration
Register the TodoListResource class to handle routes for listing and creating todos (‘/todos’) and the TodoResource class to handle routes for individual todos (‘/todos/<int:todo_id>’). Start the Flask application if the script is run directly.
Python3
api.add_resource(TodoListResource, '/todos')
api.add_resource(TodoResource, '/todos/<int:todo_id>')
if __name__ == '__main__':
app.run(debug=True)
|
Step 5: Run the Mock Server:
Execute the Python script (python app.py). To execute the script, open a terminal and navigate to the project directory then run the command:
python app.py
Now, access Swagger UI at http://127.0.0.1:5000/apidocs/ to interact with the mock API.
http://127.0.0.1:5000/apidocs/
Output
Video Demonstration
Building Mock API Using Swagger Another Example
Below is the step-by-step procedure to build another mock APIs with Swagger in Python.
Note: We are using same file structure as above.
Folder Structure
|--->books.py
|--->swagger_books.yml
Step 1: Create Swagger Specification (swagger_books.yml)
In this code, a Swagger 2.0 specification defines a simple Book API with CRUD operations, including endpoints for retrieving all books, creating a new book, and managing individual books by ID through GET, PUT, and DELETE operations. The API documentation is structured to include details about book title, author, and appropriate HTTP responses.
Python3
swagger: '2.0'
info:
title: Book API
description: Simple Book API with CRUD operations
version: '1.0'
paths:
/books:
get:
summary: Get all books
responses:
'200':
description: A list of books
post:
summary: Create a new book
parameters:
- name: book
in: body
required: true
schema:
type: object
properties:
title:
type: string
description: The title of the book
author:
type: string
description: The author of the book
responses:
'201':
description: Book created successfully
/books/{book_id}:
parameters:
- name: book_id
in: path
required: true
type: integer
get:
summary: Get a specific book by ID
responses:
'200':
description: Book details
'404':
description: Book not found
put:
summary: Update a specific book by ID
parameters:
- name: book
in: body
required: true
schema:
type: object
properties:
title:
type: string
description: The updated title
author:
type: string
description: The updated author
responses:
'200':
description: Book updated successfully
'404':
description: Book not found
delete:
summary: Delete a specific book by ID
responses:
'200':
description: Book deleted successfully
'404':
description: Book not found
|
Step 2: Write Python Script
In this Python code, a Flask application with Flask-Restful is implemented to create a Book API. Endpoints for managing books include GET, PUT, DELETE, and POST methods, with Swagger used for API documentation based on the provided Swagger YAML template (‘swagger_books.yml’). The code defines resources for book details, supports CRUD operations, and runs a development server when executed.
books.py
Python3
from flask import Flask, request
from flask_restful import Api, Resource
from flasgger import Swagger
app = Flask(__name__)
api = Api(app)
swagger = Swagger(app, template_file='swagger_books.yml')
books = []
class BookResource(Resource):
def get(self, book_id):
book = next((b for b in books if b['id'] == book_id), None)
if book:
return book
else:
return {'message': 'Book not found'}, 404
def put(self, book_id):
book = next((b for b in books if b['id'] == book_id), None)
if book:
book['title'] = request.json.get('title', book['title'])
book['author'] = request.json.get('author', book['author'])
return {'message': 'Book updated successfully'}
else:
return {'message': 'Book not found'}, 404
def delete(self, book_id):
global books
books = [b for b in books if b['id'] != book_id]
return {'message': 'Book deleted successfully'}
class BookListResource(Resource):
def get(self):
return {'books': books}
def post(self):
new_book = {
'id': len(books) + 1,
'title': request.json['title'],
'author': request.json['author']
}
books.append(new_book)
return {'message': 'Book created successfully'}, 201
api.add_resource(BookListResource, '/books')
api.add_resource(BookResource, '/books/<int:book_id>')
if __name__ == '__main__':
app.run(debug=True)
|
Step 5: Run the Mock Server
Execute the Python script (python app.py). To execute the script, open a terminal and navigate to the project directory then run the command:
python books.py
Now, access Swagger UI at http://127.0.0.1:5000/apidocs/ to interact with the mock API.
http://127.0.0.1:5000/apidocs/
Video Demonstration
Please Login to comment...