FreqProcessor: Added support for nested fields.

plus data type check added

scripts/freq/freqProcessor.py

@@ -208,16 +208,34 @@ class FreqProcessor(AbstractProcessor):
         Get domain form record, compute probability using the FreqCounter,
         and store the resulting probabilities to the record.
         """
-        text = record.getValue(self.input_field_name)
-        if text is None:
-            # FlowFile attribute tells we should take the domain from the field
-            # names as $input_field_name, but such a field i not present in the
-            # record.
-            # Don't set the result fields
-            self.logger.warn("The 'Input field' attribute points to '{}' field which is not present in the record.".format(self.input_field_name))
-            return
+        # Get value of given field.
+        # The field name may look like 'xx/yy/zz'. There can be a field with
+        # exactly this key (incl. slashes), or there can be tree of nested
+        # keys/sub-objects.
+        # First, try to get the field by its full name.
+        value = record.getValue(self.input_field_name)
+        if value is None:
+            # The field named exactly as $input_field_name is not present in
+            # the record. Maybe it's a nested key ...
+            if "/" in self.input_field_name:
+                path_parts = self.input_field_name.split('/')
+                # Get first sub-key/sub-object (returns another MapRecord or None)
+                value = record.getValue(path_parts.pop(0))
+                # iterate any possible sub-objects to final sub-key
+                while value and path_parts:
+                    value = value.getValue(path_parts.pop(0))
+            
+            # If value is still None, the field is not there
+            # -> don't set the result fields
+            if value is None:
+                self.logger.warn("The 'Input field' attribute points to '{}' field which is not present in the record, record skipped.".format(self.input_field_name))
+                return
 
-        prob1, prob2 = self.fc.probability(text)
+        if not isinstance(value, (str, unicode)):
+            self.logger.warn("Value of the '{}' field is not a string, record skipped.".format(self.input_field_name))
+            return
+        
+        prob1, prob2 = self.fc.probability(value)
 
         record.setValue(self.result1_field_name, prob1)
         record.setValue(self.result2_field_name, prob2)