[add] added supported for filter expressions on aggregations. include…

… more examples on test_builder.py

redisearch/aggregation.py

@@ -104,7 +104,7 @@ def build_args(self):
  for reducer in self.reducers:
  ret += ['REDUCE', reducer.NAME, str(len(reducer.args))]
  ret.extend(reducer.args)
- if reducer._alias:
+ if reducer._alias is not None:
  ret += ['AS', reducer._alias]
  return ret
 
@@ -172,6 +172,7 @@ def __init__(self, query='*'):
  self._query = query
  self._aggregateplan = []
  self._loadfields = []
+ self._filters = []
  self._limit = Limit()
  self._max = 0
  self._with_schema = False
@@ -218,7 +219,7 @@ def apply(self, **kwexpr):
  expression itself, for example `apply(square_root="sqrt(@foo)")`
  """
  for alias, expr in kwexpr.items():
- projection = Projection(alias, expr)
+ projection = Projection(expr, alias )
  self._aggregateplan.extend(projection.build_args())
 
  return self
@@ -306,6 +307,22 @@ def sort_by(self, *fields, **kwargs):
  self._aggregateplan.extend(sortby.build_args())
  return self
 
+ def filter(self, expressions):
+ """
+ Specify filter for post-query results using predicates relating to values in the result set.
+
+ ### Parameters
+
+ - **fields**: Fields to group by. This can either be a single string,
+ or a list of strings.
+ """
+ if isinstance(expressions, (string_types)):
+ expressions = [expressions]
+
+ self._filters.extend(expressions)
+
+ return self
+
  def with_schema(self):
  """
  If set, the `schema` property will contain a list of `[field, type]`
@@ -353,6 +370,10 @@ def build_args(self):
 
  ret.extend(self._aggregateplan)
 
+ for expr in self._filters:
+ ret.append('FILTER')
+ ret.append(expr)
+
  ret += self._limit.build_args()
 
  return ret

test/test_builder.py

@@ -62,6 +62,10 @@ def testAggRequest(self):
  req = a.AggregateRequest().group_by('@foo', r.count())
  self.assertEqual(['*', 'GROUPBY', '1', '@foo', 'REDUCE', 'COUNT', '0'], req.build_args())
 
+ # Test with group_by and alias on reducer
+ req = a.AggregateRequest().group_by('@foo', r.count().alias('foo_count'))
+ self.assertEqual(['*', 'GROUPBY', '1', '@foo', 'REDUCE', 'COUNT', '0', 'AS', 'foo_count'], req.build_args())
+
  # Test with limit
  req = a.AggregateRequest(). \
  group_by('@foo', r.count()). \
@@ -77,6 +81,10 @@ def testAggRequest(self):
  self.assertEqual(['*', 'APPLY', '@bar / 2', 'AS', 'foo', 'GROUPBY', '1', '@foo', 'REDUCE', 'COUNT', '0'],
  req.build_args())
 
+ # Test with filter
+ req = a.AggregateRequest().group_by('@foo', r.count()).filter( "@foo=='bar'")
+ self.assertEqual(['*', 'GROUPBY', '1', '@foo', 'REDUCE', 'COUNT', '0', 'FILTER', "@foo=='bar'" ], req.build_args())
+
  # Test with sort_by
  req = a.AggregateRequest().group_by('@foo', r.count()).sort_by('@date')
  # print req.build_args()