Creating a REST Api using Flask-Restful and MongoDB

About REST

REST (Representational State Transfer) is an architecture style for designing networked applications. The idea is using simple HTTP methods for making calls between machines rather than complex mechanisms such as CORBA, RPC or SOAP. So a RESTful system typically communicates over the Hypertext Transfer Protocol with the same HTTP verbs (GET, POST, PUT, DELETE, etc.)

Flask and Flask-RESTful

Flask is a microframework for Python based on Werkzeug, Jinja2. Flask-RESTful provides an extension to Flask for building REST APIs.

Installing packages

For the api, we need to install some packages like Flask-Restful, pymongo etc. It’s good practice to install packages and modules for a project in a virtual environment. So i am going to create a virtual environment and activate it.

$ virtualenv env
$ source env/bin/activate

Now the required packages can be installed using pip. (Link: requirements.txt)

$ pip install -r requirements.txt

API

Lets do the code first,

This is a basic api with only one Resource Student. First we created an instance of Flask,

app = Flask(__name__)

after that we configured app with MongoDB. The resource Student has HTTP methods defined in it as it’s own method. By calling different HTTP methods we can perform basic CRUD operations. Like post method for inserting/creating, put for updating, get for reading and delete for deleting a document.

In the code post, put, delete methods are basic. These methods perform create, update and delete operation on the collection student.

But in the get method, by calling different url we can perform different operations. If no parameter passed with url, the method will return all the documents in the collection. If a registration number passed with the url then, it will check the parameter name and will return one document. If request is made in /api/department/<string:department> url, it will check for parameter name department in the get method and returns all the documents for a particular department.

There are several urls for same resource so we added different endpoints for them.

Testing

We will use python requests module (version > 2.4.2) for testing the api. But also curl and other mechanism can be used. For get request we can view the data in browsers also.

In [1]: from requests import get, post, put, delete
In [2]: get("http://127.0.0.1:5000/api")
In [3]: data = {"name": "Example Name", "registration": "123433199", "department": "cse"}
In [4]: post("http://127.0.0.1:5000/api", json=data).json()
In [5]: put("http://127.0.0.1:5000/api/123433199", json={"website": "www.example.com"}).json()
In [6]: delete("http://127.0.0.1:5000/api/123433199").json()

Lets take some REST.