Python Urllib Error Module

In this short post, we will discuss the urllib.error module that defines exception classes from the urllib.request module.

The module supports the following exceptions:

1. URLError – This type of exception is raised when fetching a specific resource. The function provides a reason property which hold detailed information about the cause of the error.
2. HTTPError – This type of exception is raised in the encounter of exotic HTTP errors such as auth. Similarly, the function supports a code, reason, and headers properties that returns the HTTP status code, explanation of the error, and the HTTP response headers for the request, respectively.
3. ContentTooShortError – This exception is raised if the returned data is lass than expected amount. The data length is defined in the Content-Length header.

Example 1 – URLError Exception

The following example code shows how to use the errors raised in the errors module.

import urllib.request

try:
    r = urllib.request.urlopen("https://cloudenv.io")
    print(r.read().decode('utf-8'))  # Print the response content as a string
except Exception as e:
    print(str(e))

Keep in mind that the URLError is a subclass of OSError. Therefore, if we run the code above without internet connectivity, it should return a URLError as shown:

URL Error: urlopen error [Errno 11001] getaddrinfo failed

Example 2 - HTTPError Exception

In the example below, we illustrate how to use the urllb.error module to handle HTTPError exceptions.

import urllib.request

try:
    r = urllib.request.urlopen("https://httpstat.us/403")
    print(r.read().decode('utf-8'))
except Exception as e:
    print(str(e))

Running the code above should return a HTTPError exception as the request encounters a 403 status code.

The resulting output:

HTTP Error 403: Forbidden

Closing

In this post, we discussed how to use the urllib.error module to handle URLError and HTTPError exceptions.