server: consolidate time processing and checks

nilmdb/server/server.py

@@ -174,6 +174,21 @@ class Root(NilmApp):
 class Stream(NilmApp):
     """Stream-specific operations"""
 
+    # Helpers
+    def _get_times(self, start_param, end_param):
+        (start, end) = (None, None)
+        if start_param is not None:
+            start = string_to_timestamp(start_param)
+        if end_param is not None:
+            end = string_to_timestamp(end_param)
+        if start is not None and end is not None:
+            if start >= end:
+                raise cherrypy.HTTPError(
+                    "400 Bad Request",
+                    sprintf("start must precede end (%s >= %s)",
+                            start_param, end_param))
+        return (start, end)
+
     # /stream/list
     # /stream/list?layout=float32_8
     # /stream/list?path=/newton/prep&extended=1
@@ -307,11 +322,7 @@ class Stream(NilmApp):
             raise cherrypy.HTTPError("404 Not Found", "No such stream")
 
         # Check limits
-        start = string_to_timestamp(start)
-        end = string_to_timestamp(end)
-        if start >= end:
-            raise cherrypy.HTTPError("400 Bad Request",
-                                     "start must precede end")
+        (start, end) = self._get_times(start, end)
 
         # Pass the data directly to nilmdb, which will parse it and
         # raise a ValueError if there are any problems.
@@ -333,14 +344,7 @@ class Stream(NilmApp):
         the interval [start, end).  Returns the number of data points
         removed.
         """
-        if start is not None:
-            start = string_to_timestamp(start)
-        if end is not None:
-            end = string_to_timestamp(end)
-        if start is not None and end is not None:
-            if start >= end:
-                raise cherrypy.HTTPError("400 Bad Request",
-                                         "start must precede end")
+        (start, end) = self._get_times(start, end)
         total_removed = 0
         while True:
             (removed, restart) = self.db.stream_remove(path, start, end)
@@ -371,15 +375,7 @@ class Stream(NilmApp):
         Note that the response type is the non-standard
         'application/x-json-stream' for lack of a better option.
         """
-        if start is not None:
-            start = string_to_timestamp(start)
-        if end is not None:
-            end = string_to_timestamp(end)
-
-        if start is not None and end is not None:
-            if start >= end:
-                raise cherrypy.HTTPError("400 Bad Request",
-                                         "start must precede end")
+        (start, end) = self._get_times(start, end)
 
         if len(self.db.stream_list(path = path)) != 1:
             raise cherrypy.HTTPError("404", "No such stream: " + path)
@@ -417,16 +413,7 @@ class Stream(NilmApp):
         If 'markup' is True, adds comments to the stream denoting each
         interval's start and end timestamp.
         """
-        if start is not None:
-            start = string_to_timestamp(start)
-        if end is not None:
-            end = string_to_timestamp(end)
-
-        # Check parameters
-        if start is not None and end is not None:
-            if start >= end:
-                raise cherrypy.HTTPError("400 Bad Request",
-                                         "start must precede end")
+        (start, end) = self._get_times(start, end)
 
         # Check path and get layout
         streams = self.db.stream_list(path = path)