REQUEST - how to POST?

John1 · July 18, 2023, 7:26am

Hi,

I would like to use the REQUEST function to make a POST, PUT, or DELETE request, to use Grist to modify external state. At first glance, this might seem like a crazy thing to want do, however, there is a sensible way to modify external state outside of Grist.

My use case is I would like to automatically install an n8n workflow using Grist, only using the document and not require any plugins.

I have an n8n_integrations table, and a toggle for “install n8n workflow”. Based on the value of $install_n8n_workflow, I would have another column that would use REQUEST to idempotently make the state of this n8n workflow installed or not installed, and return its current state.

I believe this way of doing it is consistent with a database-spreadsheet hybrid that supports Python.

How can I make REQUEST submit POST, PUT, and DELETE requests? Alternatively, which part of the source code should I modify to get this to work?

Thanks a lot

paul-grist · July 19, 2023, 7:52pm

Hi @John1, good job at forestalling my “this is crazy” response. Doing this would require source code changes. First I guess would be to add a slot for specifying the request method type here:

github.com

gristlabs/grist-core/blob/f1e8cba57f02b1a24cb842923f6c261b868e4079/app/common/ActionBundle.ts#L72C1-L78


      
          // Represents a unique call to the Python REQUEST function
          export interface SandboxRequest {
            url: string;
            params: Record<string, string> | null;
            headers: Record<string, string> | null;
            deps: unknown;  // pass back to the sandbox unchanged in the response
          }

Then tweak the REQUEST method to let you pass it:

github.com

gristlabs/grist-core/blob/f1e8cba57f02b1a24cb842923f6c261b868e4079/sandbox/grist/functions/info.py#L661-L670


      
          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()

Then tweak the DocRequests method to honor the setting:

github.com

gristlabs/grist-core/blob/f1e8cba57f02b1a24cb842923f6c261b868e4079/app/server/lib/Requests.ts#L81-L92


      
          private async _handleSingleRequestRaw(request: SandboxRequest): Promise<Response> {
            try {
              if (process.env.GRIST_EXPERIMENTAL_PLUGINS != '1') {
                throw new Error("REQUEST is not enabled");
              }
              const {url, params, headers} = request;
              const urlObj = new URL(url);
              log.rawInfo("Handling sandbox request", {host: urlObj.host, docId: this._activeDoc.docName});
              for (const [param, value] of Object.entries(params || {})) {
                urlObj.searchParams.append(param, value);
              }
              const response = await fetch(urlObj.toString(), {headers: headers || {}, agent: proxyAgent(urlObj)});

I think that’s it. If others can access your Grist instance, I’d strongly suggest setting up GRIST_HTTPS_PROXY before letting them make arbitrary api calls to any internal endpoints you have.

John1 · July 20, 2023, 6:53am

Thanks @paul-grist - that helps massively!

John1 · July 24, 2023, 7:54am

Ok - now done! Please can you take a look at my PR? REQUEST now supports POST by johncant · Pull Request #588 · gristlabs/grist-core · GitHub