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Using the Python debugger with Requests

Introduction​

The Python debugger (pdb) is a powerful tool to inspect and troubleshoot your Python code. When combined with Requests, a popular Python library for making HTTP requests, pdb can help you understand the flow of your program, examine data, and identify bugs. This tutorial will guide you through the process of using pdb with Requests.

Setting up the environment​

Before we start, ensure you have Python and Requests installed. If not, install Python from python.org, then install Requests by running:

pip install requests

Using pdb in Python​

To use pdb, you need to import it in your Python script. You can set a breakpoint where you want your code execution to pause using pdb.set_trace().

import pdb
import requests

def get_website_content(url):
    response = requests.get(url)
    pdb.set_trace()
    return response.text

When the pdb.set_trace() line is executed, your program will pause, and you'll be able to inspect your code.

Running the debugger​

To run your script with the debugger, use the Python command followed by the name of your script. When your code hits the pdb.set_trace() breakpoint, you will be placed into an interactive prompt.

python your_script.py

pdb commands​

Below are some of the most useful pdb commands:

  • l(list): Display 11 lines around the current line or continue the previous listing.
  • s(step): Execute the current line and stop at the first possible occasion.
  • n(next): Continue execution until the next line in the current function is reached or it returns.
  • p(print): Evaluate the expression in the current context and print its value.

Debugging a request​

Let's debug a simple request to an API:

import pdb
import requests

def get_data():
    response = requests.get('https://api.github.com/events')
    pdb.set_trace()
    return response.json()

get_data()

Run this script, and the program will stop at pdb.set_trace(). You can now use pdb commands to inspect the response.

# print the status code
p response.status_code

# print the headers
p response.headers

# print the first 500 characters of the response body
p response.text[:500]

Conclusion​

Python's built-in debugger is a powerful tool to debug your HTTP requests. It allows you to pause your program, inspect your data, and isolate issues. Practice using pdb and its various commands to become more efficient in your debugging. Happy coding!