Issue1414: wrong behavior of json() method with nested models containing custom root

changes/1414-silversurfer34.md

@@ -0,0 +1 @@
+Change the behavior of json() method to remove the extra `__root__` keys in the result when using nested models with custom root types

pydantic/main.py

@@ -428,8 +428,28 @@ def json(
             exclude_defaults=exclude_defaults,
             exclude_none=exclude_none,
         )
-        if self.__custom_root_type__:
-            data = data[ROOT_KEY]
+
+        def reparent_root(d: 'DictStrAny') -> 'DictStrAny':
+            """
+            Parse the input dictionary, search for the keys "__root__" and take the associated values and reparent them
+            to "__root__" parent
+            """
+            result = dict()
+            for k, v in d.items():
+                if isinstance(v, dict):
+                    if k is not ROOT_KEY:
+                        result[k] = reparent_root(v)
+                    else:
+                        return reparent_root(v)
+                else:
+                    if k is not ROOT_KEY:
+                        result[k] = v
+                    else:
+                        return v
+            return result
+
+        res = reparent_root(data)
+        data = res
         return self.__config__.json_dumps(data, default=encoder, **dumps_kwargs)
 
     @classmethod

tests/test_json.py

@@ -204,6 +204,37 @@ class Model(BaseModel):
     assert Model(__root__=['a', 'b']).json() == '["a", "b"]'
 
 
+def test_encode_nested_root():
+    class Pets(BaseModel):
+        __root__: List[str]
+
+    class PetHouse(BaseModel):
+        Animals: Pets
+        Location: str
+
+    assert (
+        PetHouse(**{'Animals': ['dog', 'cat'], 'Location': 'Montpellier'}).json()
+        == '{"Animals": ["dog", "cat"], "Location": "Montpellier"}'
+    )
+
+
+def test_encode_several_nested_root():
+    class PetsAlias(BaseModel):
+        __root__: List[str]
+
+    class Pets(BaseModel):
+        __root__: PetsAlias
+
+    class PetHouse(BaseModel):
+        Animals: Pets
+        Location: str
+
+    assert (
+        PetHouse(**{'Animals': ['dog', 'cat'], 'Location': 'Montpellier'}).json()
+        == '{"Animals": ["dog", "cat"], "Location": "Montpellier"}'
+    )
+
+
 def test_custom_decode_encode():
     load_calls, dump_calls = 0, 0
 

tests/test_schema.py

@@ -1432,6 +1432,23 @@ class Model(BaseModel):
     }
 
 
+def test_nested_root_model():
+    class Pets(BaseModel):
+        __root__: List[str]
+
+    class PetHouse(BaseModel):
+        Animals: Pets
+        Location: str
+
+    assert PetHouse.schema() == {
+        'title': 'PetHouse',
+        'type': 'object',
+        'properties': {'Animals': {'$ref': '#/definitions/Pets'}, 'Location': {'title': 'Location', 'type': 'string'}},
+        'required': ['Animals', 'Location'],
+        'definitions': {'Pets': {'title': 'Pets', 'type': 'array', 'items': {'type': 'string'}}},
+    }
+
+
 def test_new_type_schema():
     a_type = NewType('a_type', int)
     b_type = NewType('b_type', a_type)