Remove temporary True/False handling from _execute_query()

method. The new where-clause implementation now implements
full predicate handling.

Update CHANGELOG with new where-clause predicate handling.

CHANGELOG

@@ -6,6 +6,7 @@ COMING SOON (0.9.2)
 -------------------
 
 * Improved data handling features and Python 3.7 support.
+* Changed Selector class keyword filtering to support predicate matching.
 * Changed Query class:
     * Added flatten() method to serialize dictionary results.
     * Added to_csv() method to quickly save results as a CSV file.

datatest/_query/query.py

@@ -1028,13 +1028,6 @@ def to_csv(self, file, fieldnames=None, **fmtparams):
     ])
 
 
-# Temporary functions for "where" keyword args.
-# NOTE!!!: Remove these after implementing full
-# predicate support for keyword filtering.
-_is_truthy = lambda x: bool(x)
-_is_falsy = lambda x: not bool(x)
-
-
 class Selector(object):
     """A class to quickly load and select tabular data. The given
     *objs*, *\*args*, and *\*\*kwds*, can be any values supported
@@ -1207,13 +1200,6 @@ def __call__(self, columns, **where):
     def _execute_query(self, select_clause, trailing_clause=None, **kwds_filter):
         """Execute query and return cursor object."""
         try:
-            for key, val in kwds_filter.items():  # Temporary partial keyword
-                if val is True:                   # handling to use until full
-                    val = _is_truthy              # predicate support is ready.
-                elif val is False:
-                    val = _is_falsy
-                kwds_filter[key] = val
-
             # Build select-query.
             stmnt = 'SELECT {0} FROM {1}'.format(select_clause, self._table)
             where_clause, params = self._build_where_clause(kwds_filter)

tests/test_query.py

@@ -1249,6 +1249,15 @@ def test_build_where_clause(self):
         self.assertEqual(result[1], [])
         self.assertEqual(len(select._user_function_dict), prev_len + 1)
 
+        # Predicate (a boolean)
+        prev_len = len(select._user_function_dict)
+        predicate = True
+        result = select._build_where_clause({'A': predicate})
+        self.assertEqual(len(result), 2)
+        self.assertRegex(result[0], r'FUNC\d+\(A\)')
+        self.assertEqual(result[1], [])
+        self.assertEqual(len(select._user_function_dict), prev_len + 1)
+
     def test_execute_query(self):
         data = [['A', 'B'], ['x', 101], ['y', 202], ['z', 303]]
         source = Selector(data)