feat: add decimal validation for numeric precision and scale supported by Spanner (#340)

* feat: updated googleapis proto changes for request tags * feat: added support for numberic for python decimal value * feat: add decimal validation for numeric precission and scale supported by spanner * fix: moved decimal validation from spanner_dbapi to spanner_v1/helper function

Author: vi3k6i5

google/cloud/spanner_v1/_helpers.py

@@ -30,6 +30,16 @@
 from google.cloud.spanner_v1 import ExecuteSqlRequest
 
 
+# Validation error messages
+NUMERIC_MAX_SCALE_ERR_MSG = (
+ "Max scale for a numeric is 9. The requested numeric has scale {}"
+)
+NUMERIC_MAX_PRECISION_ERR_MSG = (
+ "Max precision for the whole component of a numeric is 29. The requested "
+ + "numeric has a whole component with precision {}"
+)
+
+
 def _try_to_coerce_bytes(bytestring):
  """Try to coerce a byte string into the right thing based on Python
  version and whether or not it is base64 encoded.
@@ -87,6 +97,28 @@ def _merge_query_options(base, merge):
  return combined
 
 
+def _assert_numeric_precision_and_scale(value):
+ """
+ Asserts that input numeric field is within Spanner supported range.
+
+ Spanner supports fixed 38 digits of precision and 9 digits of scale.
+ This number can be optionally prefixed with a plus or minus sign.
+ Read more here: https://cloud.google.com/spanner/docs/data-types#numeric_type
+
+ :type value: decimal.Decimal
+ :param value: The value to check for Cloud Spanner compatibility.
+
+ :raises NotSupportedError: If value is not within supported precision or scale of Spanner.
+ """
+ scale = value.as_tuple().exponent
+ precision = len(value.as_tuple().digits)
+
+ if scale < -9:
+ raise ValueError(NUMERIC_MAX_SCALE_ERR_MSG.format(abs(scale)))
+ if precision + scale > 29:
+ raise ValueError(NUMERIC_MAX_PRECISION_ERR_MSG.format(precision + scale))
+
+
 # pylint: disable=too-many-return-statements,too-many-branches
 def _make_value_pb(value):
  """Helper for :func:`_make_list_value_pbs`.
@@ -129,6 +161,7 @@ def _make_value_pb(value):
  if isinstance(value, ListValue):
  return Value(list_value=value)
  if isinstance(value, decimal.Decimal):
+ _assert_numeric_precision_and_scale(value)
  return Value(string_value=str(value))
  raise ValueError("Unknown type: %s" % (value,))
 

tests/unit/spanner_dbapi/test_parse_utils.py

@@ -254,8 +254,6 @@ def test_rows_for_insert_or_update(self):
 
  @unittest.skipIf(skip_condition, skip_message)
  def test_sql_pyformat_args_to_spanner(self):
- import decimal
-
  from google.cloud.spanner_dbapi.parse_utils import sql_pyformat_args_to_spanner
 
  cases = [
@@ -300,16 +298,6 @@ def test_sql_pyformat_args_to_spanner(self):
  ("SELECT * from t WHERE id=10", {"f1": "app", "f2": "name"}),
  ("SELECT * from t WHERE id=10", {"f1": "app", "f2": "name"}),
  ),
- (
- (
- "SELECT (an.p + %s) AS np FROM an WHERE (an.p + %s) = %s",
- (1, 1.0, decimal.Decimal("31")),
- ),
- (
- "SELECT (an.p + @a0) AS np FROM an WHERE (an.p + @a1) = @a2",
- {"a0": 1, "a1": 1.0, "a2": decimal.Decimal("31")},
- ),
- ),
  ]
  for ((sql_in, params), sql_want) in cases:
  with self.subTest(sql=sql_in):

tests/unit/test__helpers.py

@@ -233,6 +233,65 @@ def test_w_unknown_type(self):
  with self.assertRaises(ValueError):
  self._callFUT(object())
 
+ def test_w_numeric_precision_and_scale_valid(self):
+ import decimal
+ from google.protobuf.struct_pb2 import Value
+
+ cases = [
+ decimal.Decimal("42"),
+ decimal.Decimal("9.9999999999999999999999999999999999999E+28"),
+ decimal.Decimal("-9.9999999999999999999999999999999999999E+28"),
+ decimal.Decimal("99999999999999999999999999999.999999999"),
+ decimal.Decimal("1E+28"),
+ decimal.Decimal("1E-9"),
+ ]
+ for value in cases:
+ with self.subTest(value=value):
+ value_pb = self._callFUT(value)
+ self.assertIsInstance(value_pb, Value)
+ self.assertEqual(value_pb.string_value, str(value))
+
+ def test_w_numeric_precision_and_scale_invalid(self):
+ import decimal
+ from google.cloud.spanner_v1._helpers import (
+ NUMERIC_MAX_SCALE_ERR_MSG,
+ NUMERIC_MAX_PRECISION_ERR_MSG,
+ )
+
+ max_precision_error_msg = NUMERIC_MAX_PRECISION_ERR_MSG.format("30")
+ max_scale_error_msg = NUMERIC_MAX_SCALE_ERR_MSG.format("10")
+
+ cases = [
+ (
+ decimal.Decimal("9.9999999999999999999999999999999999999E+29"),
+ max_precision_error_msg,
+ ),
+ (
+ decimal.Decimal("-9.9999999999999999999999999999999999999E+29"),
+ max_precision_error_msg,
+ ),
+ (
+ decimal.Decimal("999999999999999999999999999999.99999999"),
+ max_precision_error_msg,
+ ),
+ (
+ decimal.Decimal("-999999999999999999999999999999.99999999"),
+ max_precision_error_msg,
+ ),
+ (
+ decimal.Decimal("999999999999999999999999999999"),
+ max_precision_error_msg,
+ ),
+ (decimal.Decimal("1E+29"), max_precision_error_msg),
+ (decimal.Decimal("1E-10"), max_scale_error_msg),
+ ]
+
+ for value, err_msg in cases:
+ with self.subTest(value=value, err_msg=err_msg):
+ self.assertRaisesRegex(
+ ValueError, err_msg, lambda: self._callFUT(value),
+ )
+
 
 class Test_make_list_value_pb(unittest.TestCase):
  def _callFUT(self, *args, **kw):