How do you handle query parameters in Flask?

Read them from request.args, which holds the parsed query string as a MultiDict. A MultiDict can keep several values for one key.

from flask import request

@app.route('/search')
def search():
    query = request.args.get('q', '')
    page = request.args.get('page', 1, type=int)
    category = request.args.getlist('category')  # Multiple values
    
    return f'Query: {query}, Page: {page}, Categories: {category}'

• get('q', '') returns the default when the key is missing.
• get('page', 1, type=int) converts the value and falls back to the default when the conversion fails, so ?page=abc gives 1.
• getlist('category') returns every value, so ?category=a&category=b gives both, and a missing key gives an empty list.

Indexing with request.args['q'] raises a KeyError for a missing key, and Flask turns that into 400 Bad Request. Prefer get(), because users can edit a URL by hand. Values arrive as strings until you convert them.