Support Decimal() type.

Author: flipbit03

graphene_sqlalchemy/converter.py

@@ -1,5 +1,6 @@
 import datetime
 import typing
+from decimal import Decimal
 from functools import singledispatch
 from typing import Any
 
@@ -288,6 +289,14 @@ def convert_hybrid_property_return_type_inner_float(arg):
     return Float
 
 
+@convert_hybrid_property_return_type_inner.register(value_equals(Decimal))
+def convert_hybrid_property_return_type_inner_decimal(arg):
+    # The reason Decimal should be serialized as a String is because this is a
+    # base10 type used in things like money, and string allows it to not
+    # lose precision (which would happen if we downcasted to a Float, for example)
+    return String
+
+
 @convert_hybrid_property_return_type_inner.register(value_equals(bool))
 def convert_hybrid_property_return_type_inner_bool(arg):
     return Boolean

graphene_sqlalchemy/tests/models.py

@@ -2,6 +2,7 @@
 
 import datetime
 import enum
+from decimal import Decimal
 from typing import List
 
 from sqlalchemy import (Column, Date, Enum, ForeignKey, Integer, String, Table,
@@ -115,6 +116,10 @@ def hybrid_prop_time(self) -> datetime.time:
     def hybrid_prop_datetime(self) -> datetime.datetime:
         return datetime.datetime.now()
 
+    @hybrid_property
+    def hybrid_prop_decimal(self) -> Decimal:
+        return Decimal("3.14")
+
     @hybrid_property
     def hybrid_prop_first_article(self) -> Article:
         return self.articles[0]

graphene_sqlalchemy/tests/test_types.py

@@ -106,6 +106,7 @@ class Meta:
         "hybrid_prop_date",
         "hybrid_prop_time",
         "hybrid_prop_datetime",
+        "hybrid_prop_decimal",
         "hybrid_prop_first_article",
         # Relationship
         "pets",
@@ -174,6 +175,11 @@ class Meta:
     assert hybrid_prop_datetime.type == DateTime
     assert hybrid_prop_datetime.description is None  # "doc" is ignored by hybrid_property
 
+    hybrid_prop_decimal = ReporterType._meta.fields['hybrid_prop_decimal']
+    # Decimal (base10) should serialize to String for correctness.
+    assert hybrid_prop_decimal.type == String
+    assert hybrid_prop_decimal.description is None  # "doc" is ignored by hybrid_property
+
     # relationship
     favorite_article_field = ReporterType._meta.fields['favorite_article']
     assert isinstance(favorite_article_field, Dynamic)
@@ -251,6 +257,7 @@ class Meta:
         "hybrid_prop_date",
         "hybrid_prop_time",
         "hybrid_prop_datetime",
+        "hybrid_prop_decimal",
         "hybrid_prop_first_article",
     ])
 
@@ -367,6 +374,7 @@ class Meta:
         "hybrid_prop_date",
         "hybrid_prop_time",
         "hybrid_prop_datetime",
+        "hybrid_prop_decimal",
         "hybrid_prop_first_article",
     ])
 
@@ -488,7 +496,7 @@ class Meta:
 
     assert issubclass(CustomReporterType, ObjectType)
     assert CustomReporterType._meta.model == Reporter
-    assert len(CustomReporterType._meta.fields) == 21
+    assert len(CustomReporterType._meta.fields) == 22
 
 
 # Test Custom SQLAlchemyObjectType with Custom Options