🚧 [#4908] Add processing of attachments in plugin

The content of the attachment is now added to the result

src/openforms/registrations/contrib/json/plugin.py

@@ -19,19 +19,29 @@ def register_submission(self, submission: Submission, options: OptionsT) -> None
             variable.key: variable.initial_value for variable in static_variables
         }
 
+        values = {}
+        if submission.attachments.exists():
+            for attachment in submission.attachments:
+                if not attachment.form_key in options["form_variables"]:
+                    continue
+                options["form_variables"].remove(attachment.form_key)
+                with attachment.content.open("rb") as f:
+                    values[attachment.form_key] = f.read()
+
         # TODO-4908: what should the behaviour be when a form
         #  variable is not in the data or static variables?
-        values = {
+        values.update({
             form_variable: submission.data.get(
                 form_variable, static_variables_dict.get(form_variable)
             )
             for form_variable in options["form_variables"]
-        }
+        })
 
         print(values)
 
-        # TODO-4908: send `values` to some service
-        data_to_be_sent = {"values": values}
+        # TODO-4908: send `values` to the service
+        # TODO-4908: added return for testing purposes
+        return {"values": values}
 
     def check_config(self):
         pass