How do you access request data in Flask?

Import the request object and read the attribute for the part of the request you need. request looks like a global, but it is a context-local proxy, so each worker sees only the request it is handling.

from flask import request

@app.route('/form', methods=['POST'])
def handle_form():
    # Form data
    username = request.form['username']
    email = request.form.get('email', '')
    
    # Files
    if 'file' in request.files:
        file = request.files['file']
    
    # Headers
    auth_header = request.headers.get('Authorization')
    
    # Cookies
    session_id = request.cookies.get('session_id')
    
    return 'Data processed'

• request.form holds fields from a form body. form['username'] raises a KeyError when the field is missing, and Flask turns that into 400 Bad Request. form.get() returns a default instead.
• request.files holds uploads. It stays empty unless the form was sent as multipart/form-data.
• request.headers and request.cookies work like dictionaries, so get() is the safe way to read them.

Other parts sit beside these. request.args holds the query string, request.get_json() parses a JSON body, and request.method gives the HTTP method.