Creating dynamic mailto: links in Flask
I’ve spent the last month working on www.rtljobs.com, a niche job aggregator for logic design jobs. Our first scraping pipeline had some warts, so I wanted to be sure that the site had was a way to report bad job links. That way, if a user clicked on a job link that was no longer active, they could alert me that one of the job postings was taken down.
The simplest way I could think of doing this was thru email. I’ve always had a fondness for mailto: links, so I thought; why not use that here? Here’s what I came up with in my Flask application that runs RTLjobs.com:
def generate_mailto(url, recipient='fpga.rtl.jobs@gmail.com', subject="[Report] - Broken Link"):
body = f'''The following URL is having problems and may be broken:
{url}
Please investigate. Thank you!'''
body = urllib.parse.quote_plus(body)
mailto = 'mailto:?to='+recipient+'&subject='+subject+'&body='+body
return(mailto)
app.jinja_env.globals.update(generate_mailto=generate_mailto)
That last line adds generate_mailto() into Jinja2’s global namespace.
This way, you can call your function directly from a template, like this:
<a href="{{ generate_mailto(row['job_link']) }}">Report This Posting</a>
Which allows a user to click one button to generate a notification email to me, with the problematic URL already included.
This was a useful hack to help me crowdsource some feedback in the first weeks that RTLjobs was active. I’ve replaced it with some more sophisticated link health monitoring, but there’s no reason you can’t adapt this trick to other applications where a mailto: link might come in handy!