This is a small server that allows you to capture extra parameters passed in URLs.
For example, you can have a URL like this:
https://your-custom-site.herokuapp.com/?participant_label=JohnSmith&study_id=120383&gender=M
The participant_label will be passed as is; all other parameters such as 'study_id' and 'gender' will be passed to oTree as participant vars.
It uses oTree's REST API.
Clone this repo, then install dependencies with pip3 install -r requirements.txt.
Customize the constants in main.py.
To run locally, do uvicorn main:app --port 8500.
Visit a URL like:
http://localhost:8500/?participant_label=JohnSmith&aaa=120383&&bbb=h9w132
Observe how the participant vars get recorded into oTree.
Then, deploy to Heroku with:
heroku create
git push heroku master
heroku open
Now, rather than going directly to your oTree site, participants should come to this site, which will redirect them to your oTree site.