How to return the status code in Flask
What is Flask?
Flask is a lightweight Python framework for quick and rapid web application development.
What are status codes in HTTP?
HTTP response status codes are used in web development to determine whether a particular HTTP request has been completed successfully.
Status code in a tuple
The view function can return the status code as one of a tuple’s elements. A response object is automatically created from the return result of a view function. It is possible to get a tuple back that contains additional information. The tuple with the status code to be returned can be in any of the following formats:
(response, status_code)(response, status_code, headers)
Code
from flask import Flask, make_response, request
app = Flask(__name__)
@app.route("/userDetails", methods=["GET", "POST"])
def user_details():
if request.method == "POST":
username = request.form.get("username")
firstname = request.form.get("firstname")
lastname = request.form["lastname"]
return "Success", 201
@app.route("/userSignUp", methods=["POST"])
def sign_up():
if request.method == "POST":
username = request.form.get("username")
password = request.form.get("password")
return "Success", 200, {"Access-Control-Allow-Origin": "*"}Explanation
In the code above, the important lines to focus on are the following:
- Line 14: We are returning the response as a tuple with the response body as
Successand the status code of201. - Line 24: We are returning the response as a tuple with the response body as
Success, status code of200, and some headers as a dictionary.
Use the following curl commands to test the userDetails endpoint.
curl -X POST http://localhost:5000/userDetails -H "Content-Type: application/x-www-form-urlencoded" -d "username=sam&firstname=john&lastname=king"
Use the following curl commands to test the userSignUp endpoint.
curl -X POST http://localhost:5000/userSignUp -H "Content-Type: application/x-www-form-urlencoded" -d "username=sam&firstname=john"
The make_response() method
The make_response method from Flask returns a Response object that can be used to send custom headers and change the properties such as status_code, mimetype, and so on.
We can set the status code using the make_response method in two ways:
- Pass the status code as a constructor parameter.
- Use the property
status_codeto set the status code. Here, the value set has to be an integer.
Code
from flask import Flask, make_response, request
app = Flask(__name__)
@app.route("/userDetails", methods=["GET", "POST"])
def user_details():
if request.method == "POST":
username = request.form.get("username")
firstname = request.form.get("firstname")
lastname = request.form["lastname"]
response = make_response("<h1>Success</h1>", 201)
return response
@app.route("/userSignUp", methods=["POST"])
def sign_up():
if request.method == "POST":
username = request.form.get("username")
password = request.form.get("password")
response = make_response("<h1>Success</h1>")
response.status_code = 200
return responseExplanation
In the code above, the important lines to focus on are the following:
- Line 14: We use the
make_responsemethod to create an instance of theResponseclass. We pass the status code as a constructor parameter. - Lines 25–26: We use the
make_responsemethod to create an instance of theResponseclass. We set the status code by explicitly setting thestatus_codeproperty of the response object.
Use the following curl commands to test the userDetails endpoint.
curl -X POST http://localhost:5000/userDetails -H "Content-Type: application/x-www-form-urlencoded" -d "username=sam&firstname=john&lastname=king"
Use the following curl commands to test the userSignUp endpoint.
curl -X POST http://localhost:5000/userSignUp -H "Content-Type: application/x-www-form-urlencoded" -d "username=sam&firstname=john"
