August 31, 2020
How to calculate content-length python
Python Networking
Calculate Content Length with Python Requests
Need to know how much data a URL returns? The requests package makes it simple to fetch a page and inspect the raw payload size. This walkthrough covers installation, a sample script, and best practices.
Prerequisites
Environment
- Python 3.8 or higher
- Terminal access (Command Prompt, PowerShell, or shell)
- Internet connection to reach target URLs
Install Requests
# Windows
pip install requests
# macOS / Linux
pip3 install requestsAlready installed? Run pip show requests to confirm the version.
Step-by-Step Implementation
-
1. Import the library.
Use a simple
import requests. If you see no errors, the installation succeeded. -
2. Send a GET request.
Wrap the call in
requests.get(). Consider usingtimeoutto avoid long waits on slow servers. -
3. Inspect the response.
The
contentattribute returns the raw bytes. Use Python’slen()to measure the payload size.
Example Script
import requests
def get_content_length(url: str, timeout: int = 10) -> int:
"""Return the size (in bytes) of the response body for a URL."""
response = requests.get(url, timeout=timeout)
response.raise_for_status() # raise an exception for 4xx/5xx errors
return len(response.content)
if __name__ == "__main__":
target_url = "https://www.example.com"
try:
size_in_bytes = get_content_length(target_url)
print(f"Content length for {target_url}: {size_in_bytes} bytes")
except requests.exceptions.RequestException as exc:
print(f"Request failed: {exc}")Why handle exceptions? Production scripts should catch network issues (timeouts, DNS errors) and HTTP errors to avoid silent failures or half-fetched data.
Sample Output
Content length for https://www.example.com: 12564 bytes
Troubleshooting
Common Issues
- Timeouts: Increase the
timeoutvalue or verify connectivity. - Redirect loops: Check
response.historyfor multiple hops. - Compressed responses: Some servers gzip content—length represents compressed bytes.
Tips
- Inspect
response.headers["Content-Length"]if provided. - Use streaming (
stream=True) for large downloads to avoid memory spikes. - Combine with
loggingto audit request performance.
Python programming