Judging from your first print, it seems that Angular is sending the data in JSON format. Webapp2 will not parse this data for you. For your particular request, you can do:
import json
d = json.loads(self.request.body)
v = d.get(key)
If you want to be able to access the POST data using self.request.POST.get(key)
, you probably need to submit the data as form data. See this SO answer for more information about that.