Accessing query parameters in Flask - Mini Project: Build & Apply

Accessing query parameters in Flask

📖 Scenario: You are building a simple web app using Flask. You want to read values that users send in the URL after the question mark, called query parameters. For example, in /search?term=python, the query parameter is term with value python.

🎯 Goal: Create a Flask app that reads a query parameter called name from the URL and shows a greeting message using that name.

📋 What You'll Learn

Create a Flask app with one route /greet

Read the query parameter name from the URL

If name is missing, use Guest as default

Return a greeting message like Hello, <name>!

💡 Why This Matters

🌍 Real World

Web apps often need to read information from the URL to customize what they show. Query parameters are a common way to send small pieces of data from the browser to the server.

💼 Career

Knowing how to access query parameters is essential for backend web developers working with Flask or similar frameworks to build interactive web applications.

1

Set up the Flask app and route

Write code to import Flask and request from flask. Create a Flask app called app. Define a route for /greet using @app.route('/greet'). Inside the route function called greet, return the string 'Hello!'.

Flask

# Your code here to import Flask and request, create app, and define /greet route

Need a hint?

Remember to import both Flask and request from the flask package. Use @app.route('/greet') to create the route.

2

Get the query parameter name

Inside the greet function, create a variable called name. Use request.args.get('name') to get the name query parameter from the URL.

Flask

from flask import Flask, request

app = Flask(__name__)

@app.route('/greet')
def greet():
    # Get the 'name' query parameter from the URL
    # Your code here
    return 'Hello!'

Need a hint?

Use request.args.get('name') to read the query parameter named name.

3

Set a default value for name

Change the code to set name to request.args.get('name', 'Guest') so that if the name parameter is missing, it uses 'Guest' as the default value.

Flask

from flask import Flask, request

app = Flask(__name__)

@app.route('/greet')
def greet():
    # Get 'name' query parameter or use 'Guest' if missing
    # Your code here
    return 'Hello!'

Need a hint?

Use the second argument of get to provide a default value.

4

Return a greeting message using the name

Change the return statement to return a string that says Hello, <name>! using an f-string with the variable name.

Flask

from flask import Flask, request

app = Flask(__name__)

@app.route('/greet')
def greet():
    name = request.args.get('name', 'Guest')
    # Return greeting message using name
    # Your code here

Need a hint?

Use an f-string like f'Hello, {name}!' to include the variable in the string.