Python HTTP for Humans as cross docs data exchange

paul-grist · March 23, 2023, 6:35pm

There are some notes on installing extra python packages in self-hosted Grist here:

There is actually an undocumented, disabled REQUEST() function that works similarly to requests:

gristlabs/grist-core/blob/3faab1a03566dc68d6cb4cfa52538e5e60c77a93/sandbox/grist/functions/info.py#L661-L681


      
          def REQUEST(url, params=None, headers=None):
            # Makes a GET HTTP request with an API similar to `requests.get`.
            # Actually jumps through hoops internally to make the request asynchronously (usually)
            # while feeling synchronous to the formula writer.
          
            # Requests are identified by a string key in various places.
            # The same arguments should produce the same key so the request is only made once.
            args = dict(url=url, params=params, headers=headers)
            args_json = json.dumps(args, sort_keys=True)
            key = hashlib.sha256(args_json.encode()).hexdigest()
          
            # This may either return the raw response data or it may raise a special exception
            # to delegate the request and reevaluate the formula later.
            response_dict = docmodel.global_docmodel._engine._requesting(key, args)
          
            if "error" in response_dict:
              # Indicates a complete failure to make the request, such as a connection problem.
              # An unsuccessful status code like 404 or 500 doesn't raise this error.
              raise HTTPError(response_dict["error"])
          
            return Response(**response_dict)

You can use this method if you set GRIST_EXPERIMENTAL_PLUGINS=1 in Grist’s environment. As far as I remember, the syntax was:

response = REQUEST("...url...")
# should now have response.status_code, response.text, response.encoding, response.json()
response = REQUEST("...url...", params=dict(bar=123))  # to add query parameters conveniently

The function is disabled for a reason though, it is quite easy to make a mess using it, since cells can end up getting reevaluated for various reasons, which (when you use REQUEST) means requests get re-sent - maybe lots of them in a big doc. In trigger formulas, it could be useful. We didn’t figure out a way to communicate its limits well, and feared a big support load if we released it, so it got shelved. Apologies in advance, but I won’t be able to provide support if you use this function.