Replacing encode_default instance check with strict type check (#3197)

* Replacing encode_default instance check with strict type check

* Adding change notes

* Changing to dictionary indexing in tests

* Adding explicit Enum check and returning its value

changes/3190-joaommartins.md

@@ -0,0 +1 @@
+Always use `Enum` value as default in generated JSON schema.

pydantic/schema.py

@@ -922,7 +922,9 @@ def multitypes_literal_field_for_schema(values: Tuple[Any, ...], field: ModelFie
 
 
 def encode_default(dft: Any) -> Any:
-    if isinstance(dft, (int, float, str)):
+    if isinstance(dft, Enum):
+        return dft.value
+    elif isinstance(dft, (int, float, str)):
         return dft
     elif sequence_like(dft):
         t = dft.__class__

tests/test_schema.py

@@ -1435,6 +1435,26 @@ def test_list_default():
     }
 
 
+def test_enum_str_default():
+    class MyEnum(str, Enum):
+        FOO = 'foo'
+
+    class UserModel(BaseModel):
+        friends: MyEnum = MyEnum.FOO
+
+    assert UserModel.schema()['properties']['friends']['default'] is MyEnum.FOO.value
+
+
+def test_enum_int_default():
+    class MyEnum(IntEnum):
+        FOO = 1
+
+    class UserModel(BaseModel):
+        friends: MyEnum = MyEnum.FOO
+
+    assert UserModel.schema()['properties']['friends']['default'] is MyEnum.FOO.value
+
+
 def test_dict_default():
     class UserModel(BaseModel):
         friends: Dict[str, float] = {'a': 1.1, 'b': 2.2}