sql30: Allow range based queries.

Change here allows constraints to be based on ranges when performing various queries. Change is central so that all CRUD operations and miscellaneous operations are being able to consume it.

Author: gitvipin

sql30/db.py

@@ -219,7 +219,14 @@ def _get_fields(self, tbl_name):
  return [key for key, _ in _schema['fields'].items()]
 
  def _form_constraints(self, _separator='and', kwargs=None):
- constraints = ['%s=:%s' % (key, key) for key, _ in kwargs.items()]
+ def is_range(x): return isinstance(x, tuple) or isinstance(x, list)
+ constraints = []
+ for key, val in kwargs.items():
+ if is_range(val):
+ cparam = '%s BETWEEN %s AND %s' % (key, val[0], val[1])
+ else:
+ cparam = '%s=:%s' % (key, key)
+ constraints.append(cparam)
  return (' %s ' % _separator).join(constraints)
 
  def _validate_bfr_write(self, tbl, kwargs):

sql30/tests/test_misc.py

@@ -37,53 +37,95 @@ def setUp(self):
  self.db = Square()
  self.db.table = self.TABLE
 
- # add 3 records
+ # Populate 3 records for validating queries later.
  self.db.write(num=1, square=1)
  self.db.write(num=2, square=4)
  self.db.write(num=3, square=9)
  self.db.commit()
 
  def test_count(self):
  """
- Tests for context manager operations.
+ Tests for COUNT operations.
  """
  with Square() as db:
  db.table = self.TABLE
+ # case 1: Total numnber of records should be 3.
  self.assertEqual(db.count(), 3)
 
+ # Number of records where num is 2 should be 1.
  self.assertEqual(db.count(num=2), 1)
+
+ # Number of records where square is 9 should be 1.
  self.assertEqual(db.count(square=9), 1)
 
+ # Number of records where 4 <= square <= 9 should be 1.
+ self.assertEqual(db.count(square=[4, 9]), 2)
+
  def test_min(self):
  """
- Tests for context manager operations.
+ Tests for MIN operations.
  """
  with Square() as db:
  db.table = self.TABLE
+ # Minimum value for num is 1
  self.assertEqual(db.min('num'), 1)
+ # Minimum value for square is 1
  self.assertEqual(db.min('square'), 1)
 
+ # Minimum value for square when num = 2, is 4
  self.assertEqual(db.min('square', num=2), 4)
+ # Minimum value for square when 3 <= num <= 5, is 9
+ self.assertEqual(db.min('square', num=[3, 5]), 9)
 
  def test_max(self):
  """
- Tests for context manager operations.
+ Tests for MAX operations.
  """
  with Square() as db:
  db.table = self.TABLE
+ # Maximum value for num is 3
  self.assertEqual(db.max('num'), 3)
+ # Maximum value for square is 9
  self.assertEqual(db.max('square'), 9)
 
+ # Maximum value for square when num = 2, is 4
  self.assertEqual(db.max('square', num=2), 4)
 
+ # Minimum value for square when 0 <= num <= 5, is 9
+ self.assertEqual(db.max('square', num=[0, 5]), 9)
+
  def test_avg(self):
  """
- Tests for context manager operations.
+ Tests for AVERAGE operations.
  """
  with Square() as db:
  db.table = self.TABLE
+ # Average of all num values is 2.
  self.assertEqual(db.avg('num'), 2)
  self.assertEqual(db.avg('square', num=3), 9)
 
+ # Average value of square when 1 <= num <= 2 should be 2.5
+ self.assertEqual(db.avg('square', num=(1, 2)), 2.5)
+
+ def test_range(self):
+ """
+ Tests for RANGE operations.
+ """
+ with Square() as db:
+ db.table = self.TABLE
+ # Read records where : 0 <= num <= 3. There should be 3 records.
+ self.assertEqual(len(db.read(num=(0, 3))), 3)
+
+ # Read records where : 1 <= num <= 2. There should be 2 records.
+ self.assertEqual(len(db.read(num=(1, 2))), 2)
+
+ # Read records where : 2 < quare < 5. There should be 1 record.
+ # Also check that list based range is expected
+ self.assertEqual(len(db.read(square=[2, 5])), 1)
+
+ # Check that range is inclusive i.e. no records for :
+ # 2 <= square <= 3.
+ self.assertEqual(len(db.read(square=[2, 3])), 0)
+
  def tearDown(self):
  os.remove(DB_NAME)