A TextExpander snippet for Amazon affiliate links

• Posted 29 August 2014
• Tagged with textexpander

Earlier this evening, Casey Liss tweeted a link to a post by Stoyan Stefanov with a bookmarklet for creating Amazon affiliate links. It’s short, clean and functional. I like it, but it still needs you to copy and paste the link into your document. I wanted to cut out that step, by writing a TextExpander snippet that takes the URL of the frontmost browser window, and outputs an Amazon affiliate link.

Stefan’s post has a succinct explanation of the four components of an Amazon affiliate link:

• http://www.amazon.com/ - self-explanatory, I think
• /dp/ - standing for “details product” or maybe “details page”¹
• /1847194141/ - a 10 character product code, aka ASIN code, Amazon Standard Identification Number
• ?tag=affiliatecode-20 - your affiliate code, or tag

A typical Amazon link includes all of this information, but also includes a lot of extraneous junk:

http://www.amazon.co.uk/Special-Topics-Calamity-Physics-Marisha/dp/0141024321/ref=sr_1_1?ie=UTF8&qid=1409346826&sr=8-1&keywords=calamity+physics

By splitting at the slashes, we can extract what we want and throw away the rest. We can then use this to construct an affiliate URL.

I’ve wrapped this idea in a Python script, which I can use in TextExpander:

#!/usr/bin/env python

import re
import sys

FRONT_URL      = "%snippet:;furl%"
AFFILIATE_CODE = "123-abc-456"

if re.match('[www\.]?amazon', FRONT_URL) is None:
    print FRONT_URL
    sys.exit()

components  = FRONT_URL.split('/')
amazon_site = filter(lambda x: 'amazon' in x, components)[0]
if 'dp' in FRONT_URL:
    asin_code   = components[components.index('dp') + 1]
elif 'gp' in FRONT_URL:
    idx = components.index('gp') + 1
    if components[idx + 1] == 'product':
        asin_code = components[idx + 2]
    else:
        asin_code = components[idx + 1]

aff_link = 'http://{amazon}/dp/{asin}/?tag={aff_code}'.format(
    amazon   = amazon_site,
    asin     = asin_code,
    aff_code = AFFILIATE_CODE
)

print aff_link

This is saved as a shell script snippet in TextExpander, and I have it bound to the abbreviation ;az. Of course, I replace the AFFILIATE_CODE with my actual affiliate code.

The %snippet:;furl% component gets the front URL from the running browser, using a snippet I originally got from Dr. Drang. Then I put my affiliate code in at the top of the script.

Then I use a simple regex to check that it’s an Amazon page. If not, I just print the URL.

Next I split the URL at the slashes, and extract the domain name for that particular Amazon site, and the ASIN as the next component after /dp/. Older links have /gp/product (see footnote), so we treat those separately. Finally, I combine these pieces into an affiliate URL, and print it out. Then TextExpander types this link into my front document.

Now all I need to do is actually write a post that requires an Amazon affiliate link.

are programs used on Amazon’s backend to generate product pages, although I’ve been unable to verify that.