Add "fields" query parameter to spots and alerts API calls. Closes #140

server/handlers/api/alerts.py

@@ -58,8 +58,12 @@ class APIAlertsHandler(tornado.web.RequestHandler):
             # Fetch all alerts matching the query, then optionally enrich with online data
             credentials = extract_credentials(self.request.headers)
             data = get_alert_list_with_filters(self._alerts, query_params)
+            fields = [f.strip() for f in query_params["fields"].split(",")] if "fields" in query_params else []
             if credentials:
                 data = self._enrich(data, credentials)
+            # Filter for only the required fields, if necessary
+            if fields:
+                data = filter_fields(data, fields)
             self.write(safe_json_dumps(data))
             self.set_status(200)
         except ValueError as e:
@@ -81,6 +85,7 @@ class APIAlertsStreamHandler(tornado_eventsource.handler.EventSourceHandler):
         self._web_server_metrics = None
         self._query_params = None
         self._credentials = None
+        self._fields = None
         super().__init__(application, request, **kwargs)
 
     def initialize(self, sse_alert_broadcaster, web_server_metrics):
@@ -104,6 +109,9 @@ class APIAlertsStreamHandler(tornado_eventsource.handler.EventSourceHandler):
             # reduce that to just the first entry, and convert bytes to string
             self._query_params = {k: v[0].decode("utf-8") for k, v in self.request.arguments.items()}
             self._credentials = extract_credentials(self.request.headers)
+            self._fields = (
+                [f.strip() for f in self._query_params["fields"].split(",")] if "fields" in self._query_params else []
+            )
 
             # Flush headers immediately so nginx doesn't time out waiting for a response
             self.write_message("keepalive", "")
@@ -126,10 +134,15 @@ class APIAlertsStreamHandler(tornado_eventsource.handler.EventSourceHandler):
         """Callback when a new alert arrives"""
 
         try:
+            # If the new alert matches our param filters, send it to the client. If not, ignore it.
             if alert_allowed_by_query(alert, self._query_params):
+                # Add lookup data if we have credentials
                 if self._credentials:
                     alert = copy.deepcopy(alert)
                     alert.infer_missing(self._credentials)
+                # Filter fields returned if necessary
+                if self._fields:
+                    alert = filter_fields([alert], self._fields)[0]
                 self.write_message(msg=safe_json_dumps(alert))
         except Exception:
             logger.exception("Exception in SSE callback, connection will be closed")
@@ -216,3 +229,9 @@ def alert_allowed_by_query(alert, query):
                 ):
                     return False
     return True
+
+
+def filter_fields(alerts, fields):
+    """Given a list of alert objects, return copies containing only the named fields."""
+
+    return [{k: v for k, v in alert.__dict__.items() if k in fields} for alert in alerts]

server/handlers/api/spots.py

@@ -56,9 +56,13 @@ class APISpotsHandler(tornado.web.RequestHandler):
 
             # Fetch all spots matching the query, then optionally enrich with online data
             credentials = extract_credentials(self.request.headers)
+            fields = [f.strip() for f in query_params["fields"].split(",")] if "fields" in query_params else []
             data = get_spot_list_with_filters(self._spots, query_params)
             if credentials:
                 data = self._enrich(data, credentials)
+            # Filter for only the required fields, if necessary
+            if fields:
+                data = filter_fields(data, fields)
             self.write(safe_json_dumps(data))
             self.set_status(200)
         except ValueError as e:
@@ -80,6 +84,7 @@ class APISpotsStreamHandler(tornado_eventsource.handler.EventSourceHandler):
         self._web_server_metrics = None
         self._query_params = None
         self._credentials = None
+        self._fields = None
         super().__init__(application, request, **kwargs)
 
     def initialize(self, sse_spot_broadcaster, web_server_metrics):
@@ -105,6 +110,9 @@ class APISpotsStreamHandler(tornado_eventsource.handler.EventSourceHandler):
             # reduce that to just the first entry, and convert bytes to string
             self._query_params = {k: v[0].decode("utf-8") for k, v in self.request.arguments.items()}
             self._credentials = extract_credentials(self.request.headers)
+            self._fields = (
+                [f.strip() for f in self._query_params["fields"].split(",")] if "fields" in self._query_params else []
+            )
 
             # Flush headers immediately so nginx doesn't time out waiting for a response
             self.write_message("keepalive", "")
@@ -129,9 +137,13 @@ class APISpotsStreamHandler(tornado_eventsource.handler.EventSourceHandler):
         try:
             # If the new spot matches our param filters, send it to the client. If not, ignore it.
             if spot_allowed_by_query(spot, self._query_params):
+                # Add lookup data if we have credentials
                 if self._credentials:
                     spot = copy.deepcopy(spot)
                     spot.infer_missing(self._credentials)
+                # Filter fields returned if necessary
+                if self._fields:
+                    spot = filter_fields([spot], self._fields)[0]
                 self.write_message(msg=safe_json_dumps(spot))
         except Exception:
             logger.exception("Exception in SSE callback, connection will be closed")
@@ -266,3 +278,9 @@ def spot_allowed_by_query(spot, query):
                 if needs_good_location and not spot.dx_location_good:
                     return False
     return True
+
+
+def filter_fields(spots, fields):
+    """Given a list of spot objects, return copies containing only the named fields."""
+
+    return [{k: v for k, v in spot.__dict__.items() if k in fields} for spot in spots]