Request object properties in Flask - Step-by-Step Execution

Concept Flow - Request object properties

Client sends HTTP request

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Flask receives request

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Request object created

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Access properties: method, url, headers, args, form, json

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Use properties in route function

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Send response back to client

When Flask gets a request, it creates a Request object. You can then read its properties like method, URL, headers, and data to handle the request.

Execution Sample

Flask

from flask import Flask, request
app = Flask(__name__)

@app.route('/submit', methods=['GET', 'POST'])
def submit():
    return f"Method: {request.method}, URL: {request.url}"

This code shows how to read the HTTP method and URL from the Flask request object inside a route.

Execution Table

Step	Action	Request.method	Request.url	Output
1	Client sends GET request to /submit	GET	http://localhost/submit	None yet
2	Flask creates Request object	GET	http://localhost/submit	None yet
3	Route function runs, reads request.method and request.url	GET	http://localhost/submit	Method: GET, URL: http://localhost/submit
4	Response sent back with output string	GET	http://localhost/submit	Method: GET, URL: http://localhost/submit
5	Client receives response	GET	http://localhost/submit	Method: GET, URL: http://localhost/submit
6	Client sends POST request to /submit	POST	http://localhost/submit	None yet
7	Flask creates Request object	POST	http://localhost/submit	None yet
8	Route function runs, reads request.method and request.url	POST	http://localhost/submit	Method: POST, URL: http://localhost/submit
9	Response sent back with output string	POST	http://localhost/submit	Method: POST, URL: http://localhost/submit
10	Client receives response	POST	http://localhost/submit	Method: POST, URL: http://localhost/submit

💡 Execution stops after response is sent back to client.

Variable Tracker

Variable	Start	After Step 2	After Step 7	Final
request.method	None	GET	POST	POST
request.url	None	http://localhost/submit	http://localhost/submit	http://localhost/submit

Key Moments - 2 Insights

Why does request.method change between steps 2 and 7?

Because each HTTP request creates a new Request object with its own method property. Step 2 is for the GET request, step 7 is for the POST request.

Can request.url be different for the same route?

Yes, request.url includes the full URL including query parameters, so it can vary even if the route path is the same.

Visual Quiz - 3 Questions

Look at the execution table, what is the request.method at step 8?

A GET

B POST

C PUT

D DELETE

💡 Hint

Check the 'Request.method' column at step 8 in the execution_table.

At which step does Flask create the Request object for the POST request?

A Step 2

B Step 6

C Step 7

D Step 8

💡 Hint

Look for the step where 'Flask creates Request object' with method POST.

If the client sends a GET request with query parameters, which Request property holds them?

A request.args

B request.form

C request.json

D request.headers

💡 Hint

Query parameters are accessed via request.args in Flask.

Concept Snapshot

Flask creates a Request object for each HTTP request.
Use request.method to get HTTP method (GET, POST, etc).
Use request.url for full URL.
Use request.args for query parameters.
Use request.form for form data.
Use request.json for JSON body data.

Full Transcript

When a client sends an HTTP request to a Flask app, Flask creates a Request object representing that request. This object has properties like method, url, args, form, and json. The method tells you if the request is GET or POST. The url shows the full address requested. Query parameters are in args, form data in form, and JSON data in json. The route function can read these properties to decide how to respond. Each new request creates a new Request object with its own properties. This trace showed GET and POST requests to the same route, how Flask creates the Request object, and how the route reads method and url to build a response.