Flask Getting Started

Mar 17, 2024 · 2 min read · python ·

The tasks project

Flask is a micro web framework.
You can use it to create web sites, but also to create web services, which are programs that communicate over the http protocol.
We'll use it here to create a simple web service and api.
In our api, we'll send and receive JSON strings to represent tasks

Installation

Create a directory for you application, and cd into it (tasks in my example)
Create a python virtual environment inside your new directory
Activate your new virtual environment

1$> mkdir tasks
2$> cd tasks
3$> python3 -m venv flaskenv
4$> source flaskenv/bin/activate
5(flaskenv) $>

Now install flask:

1pip install flask

Flask Applicaion

Create your application file (tasks.py in my example)
Inside it, create your application object (with the module name as init in it):

1from flask import Flask
2
3app = Flask(__name__)

Now, register URIs, using the route method:

 1all_tasks = [
 2    None,
 3    {'id':1, 'title':'shop', 'details':'Milk'},
 4    {'id':2, 'title':'post-office', 'details':'Send Letter'},
 5    {'id':3, 'title':'phone', 'details':'Call Joan'},
 6    {'id':4, 'title':'kitchen', 'details':'Wash the dishes'},    
 7]
 8@app.route("/tasks")
 9def get_all_tasks():
10    return json.dumps(all_tasks)

I have created a list of dictionaries to represent my tasks.

When I run my application, refering to /tasks should return all of the tasks.

1$ curl http://localhost:5000/tasks
2[null, {"id": 1, "title": "shop", "details": "Milk"}, {"id": 2, "title": "post-office", "details": "Send Letter"}, {"id": 3, "title": "phone", "details": "Call Joan"}, {"id": 4, "title": "kitchen", "details": "Wash the dishes"}]
3$

Running the application

If the virtual environment is activated (in IDE or in bash), then you can just run the program itself:

1(flaskenv) $> python  tasks.py
2 * Serving Flask app 'tasks'
3 * Debug mode: off
4WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead.
5 * Running on http://127.0.0.1:5000
6Press CTRL+C to quit
7127.0.0.1 - - [17/Mar/2024 07:06:19] "GET /tasks HTTP/1.1" 200 -