#141: Make use of setAttributes() for distinct filter

- Also moved the log.debug() to the start of the function. When it was at the end, it would not be logged out if there was an exception, the situation where you want that debug statement

datagateway_api/common/icat/filters.py

@@ -117,6 +117,8 @@ def __init__(self, fields):
     def apply_filter(self, query):
         try:
             log.info("Adding ICAT distinct filter to ICAT query")
+            log.debug("Fields for distinct filter: %s", self.fields)
+
             if (
                 query.aggregate == "COUNT"
                 or query.aggregate == "AVG"
@@ -127,12 +129,9 @@ def apply_filter(self, query):
             else:
                 query.setAggregate("DISTINCT")
 
-            # Using where filters to identify which fields to apply distinct too
-            for field in self.fields:
-                where_filter = PythonICATWhereFilter(field, "null", "ne")
-                where_filter.apply_filter(query)
+            # TODO - Remove 'distinct where' logic in query class
+            query.setAttributes(self.fields)
 
-            log.debug("Fields for distinct filter: %s", self.fields)
         except ValueError as e:
             raise FilterError(e)