Hello all,
I extracted the demographic data from Prolific and also the main data from otree hub. I need to merge these two data. But, I cannot match the data together as in the data of otree there is no participants id. There is only participant code which different from participant id on Prolific. Does anyone know how can I match my data together? Is there any way to fix this problem for other experiments beforehand?

Best,
Sahar

What start link did you provide to Prolific? Did you use oTree HR?
Depending on how you deployed it, the prolific ID may be available in participant.label in oTree.

I am not sure what otree HR is. I just created an experiment with pycharm and then deployed it on Heroku with otree hub (a public project). Everything is alright except that there is no participant id the same as what I have in Prolific. The participant label column is empty.

See the section here about Prolific: https://otree.readthedocs.io/en/latest/mturk.html#prolific

If you use one of those options, Prolific ID is recorded.

Do I need to add participant_label={{%PROLIFIC_PID%}} at the end of my study link? Where exactly I should put that? Sorry I can't get it.

Try using oTree HR as described in that documentation; that will guide you through the process.

Thank you for your help. For those who are wondering: I create a new study on prolific and in the URL part I add a new parameter in configure as participant_label. The problem solved.