Ensured a Dictionary was passed to Transform & Calc Functions

bmsapp/calcs/calcreadings.py

@@ -124,8 +124,7 @@ class CalculateReadings:
 
         'calcFuncName' is a string giving the name of a method of this class.  The method
         is used to calculate new readings for the sensor database.  'calcParams' is one string
-        that is formatted like the keyword parameters of a function call; for example:
-            heat_capacity=1.08, flow=60
+        that is YAML formatted to provide keyword parameters to the function.
         
         There are two categories of functions that can be named by 'calcFuncName':
             *  Functions that expect at least one of the parameters to be the ID of an 
@@ -165,6 +164,8 @@ class CalculateReadings:
         
         # Get the function parameters as a dictionary
         params = yaml.load(calcParams)
+        if params is None:
+            params = {}    # substitute empty dictionary for no parameters
         
         # Start a List to hold the sensor IDs that need to be synchronized.  Also start
         # a separate dictionary that will map the parameter names to these IDs, since the

bmsapp/calcs/transforms.py

@@ -25,11 +25,14 @@ class Transformer:
         '''
         Returns transformed sensor reading information, using a transformation
         function identified by the string trans_func, and additional parameters to that function
-        given by the string 'trans_params'.  That string is in keyword format, like "abc=23.3, xyz=True".
+        given by the string 'trans_params'.  That string is in YAML format and must
+        convert to a Python dictionary.
         All three elements of the reading--ts, id, and val--can be transformed by the function.
         '''
         
         params = yaml.load(trans_params)
+        if params is None:
+            params = {}    # substitute an empty dictionary for empty parameter string
         if hasattr(self, trans_func.strip()):
             the_func = getattr(self, trans_func.strip())
             return the_func(ts, id, val, **params)