cck_gpx.py

cck_gpx.py is a special-purpose Python script for Cambridge Community Kitchen delivery volunteers. It reads a delivery route from the current (2022-09) web app, and copies its delivery stops into waypoints in a GPX file, which some people may find more convenient to use with mapping applications, etc.

This is hopefully a short-term stop-gap until the web app can produce GPX files natively.

The script works by parsing the HTML source of the web page, and guessing which bits are the relevant data, without any assistance from the web app. This is an awful fragile bodge, and could break at any time. cck_gpx.py is therefore quite paranoid when looking at the structure of the web page, with a fallback strategy to try to produce some useful output even when it thinks it is confused.

Prerequisites

cck_gpx.py is a standalone Python (3) script. You can just download that one file if you like; nothing else in this git repository is needed for it to run.

It depends on a few packages outside the Python standard library, which you'll need to make available. They can all be installed with pip:

pip install openlocationcode
pip install gpxpy
pip install lxml

cck_gpx.py ought to work on any platform that can run Python, although it was originally written and tested on Linux.

Usage

1. Just before a delivery shift, you'll have been sent a link to the web app; open that in a web browser, and wait for route information to be displayed. (To test the script, you can use https://app.cckitchen.uk/?p=DEMO.)
2. Save the web page to a .html file (see below).
3. Run this script, with arguments being the HTML you just saved and the name of the GPX file to create: python3 cck_gpx.py saved.html route.gpx

Three possible outcomes:

• Script says nothing and produces a GPX file: all is good.
• Script kvetches a bit, but still produces a GPX file. Read the warnings - GPX file may not have good labels, or less likely, may be missing some waypoints, but should still have some useful info. Proceed with caution.
• Script complains, and doesn't produce a GPX file at all.

If a .gpx file was produced, you can then load it into your tool of choice.

Do not rely solely on the GPX file when delivering! It deliberately doesn't try to include all the information you'll need; keep the web app and/or printed route sheet to hand too. (And please delete all copies of the GPX file when you're done with the route, since it contains personal information.)

Obtaining the HTML input

You must save the HTML from a web browser, in a specific way.

• Firefox: right-click on page; select "Save Page As..."; in the file selector, make sure that "Web Page, complete" is selected; choose a path/filename and click "Save". (This will create a _files directory as well as a .html file, but cck_gpx.py only needs the latter.)

• Chrome and derived browsers: FIXME I haven't tried this, and I don't know if there's a straightforward way to save the modified DOM; I'm seeing hints online that maybe not, so maybe you have to muck around with "Copy HTML" in dev tools, or use a browser extension? What a faff if so, sorry.

If you haven't managed to save the HTML in the right kind of way, the script will tell you and produce no output.

(Why this faff: the current web app uses client-side Javascript to fetch the actual route data and populate the DOM with it, and the script needs to see that copy. So this script can't just fetch directly from the network, since nothing would execute the Javascript in that case.)