Add JsonDict type

pydantic/__init__.py

@@ -324,6 +324,7 @@
     'GetPydanticSchema': (__package__, '.types'),
     'Tag': (__package__, '.types'),
     'CallableDiscriminator': (__package__, '.types'),
+    'JsonValue': (__package__, '.types'),
     # type_adapter
     'TypeAdapter': (__package__, '.type_adapter'),
     # warnings

pydantic/types.py

@@ -14,21 +14,23 @@
     Any,
     Callable,
     ClassVar,
+    Dict,
     FrozenSet,
     Generic,
     Hashable,
     Iterator,
     List,
     Set,
     TypeVar,
+    Union,
     cast,
 )
 from uuid import UUID
 
 import annotated_types
 from annotated_types import BaseMetadata, MaxLen, MinLen
 from pydantic_core import CoreSchema, PydanticCustomError, core_schema
-from typing_extensions import Annotated, Literal, Protocol, deprecated
+from typing_extensions import Annotated, Literal, Protocol, TypeAliasType, deprecated
 
 from ._internal import (
     _core_utils,
@@ -101,6 +103,7 @@
     'StringConstraints',
     'Tag',
     'CallableDiscriminator',
+    'JsonValue',
 )
 
 
@@ -2659,3 +2662,54 @@ def _convert_schema(self, original_schema: core_schema.CoreSchema) -> core_schem
             metadata=original_schema.get('metadata'),
             serialization=original_schema.get('serialization'),
         )
+
+
+_JSON_TYPES = {int, float, str, bool, list, dict, type(None)}
+
+
+def _get_type_name(x: Any) -> str:
+    type_ = type(x)
+    if type_ in _JSON_TYPES:
+        return type_.__name__
+
+    # Handle proper subclasses; note we don't need to handle None here
+    if isinstance(x, bool):
+        return 'bool'
+    if isinstance(x, int):
+        return 'int'
+    if isinstance(x, float):
+        return 'float'
+    if isinstance(x, str):
+        return 'str'
+    if isinstance(x, list):
+        return 'list'
+    if isinstance(x, dict):
+        return 'dict'
+
+    # Fail by returning the type's actual name
+    return getattr(type_, '__name__', '<no type name>')
+
+
+class _AllowAnyJson:
+    @classmethod
+    def __get_pydantic_core_schema__(cls, source_type: Any, handler: GetCoreSchemaHandler) -> CoreSchema:
+        python_schema = handler(source_type)
+        return core_schema.json_or_python_schema(json_schema=core_schema.any_schema(), python_schema=python_schema)
+
+
+JsonValue = TypeAliasType(
+    'JsonValue',
+    Annotated[
+        Union[
+            Annotated[List['JsonValue'], Tag('list')],
+            Annotated[Dict[str, 'JsonValue'], Tag('dict')],
+            Annotated[str, Tag('str')],
+            Annotated[int, Tag('int')],
+            Annotated[float, Tag('float')],
+            Annotated[bool, Tag('bool')],
+            Annotated[None, Tag('NoneType')],
+        ],
+        CallableDiscriminator(_get_type_name),
+        _AllowAnyJson,
+    ],
+)

tests/test_types.py

@@ -65,6 +65,7 @@
     GetCoreSchemaHandler,
     InstanceOf,
     Json,
+    JsonValue,
     NaiveDatetime,
     NameEmail,
     NegativeFloat,
@@ -6025,3 +6026,31 @@ class Model(BaseModel):
         value: str
 
     assert Model.model_validate_json(f'{{"value": {number}}}').model_dump() == {'value': expected_str}
+
+
+def test_json_value():
+    adapter = TypeAdapter(JsonValue)
+    valid_json_data = {'a': {'b': {'c': 1, 'd': [2, None]}}}
+    invalid_json_data = {'a': {'b': ...}}  # would pass validation as a dict[str, Any]
+
+    assert adapter.validate_python(valid_json_data) == valid_json_data
+    assert adapter.validate_json(json.dumps(valid_json_data)) == valid_json_data
+
+    with pytest.raises(ValidationError) as exc_info:
+        adapter.validate_python(invalid_json_data)
+    assert exc_info.value.errors() == [
+        {
+            'ctx': {
+                'discriminator': '_get_type_name()',
+                'expected_tags': "'list', 'dict', 'str', 'int', 'float', 'bool', " "'NoneType'",
+                'tag': 'ellipsis',
+            },
+            'input': Ellipsis,
+            'loc': ('dict', 'a', 'dict', 'b'),
+            'msg': "Input tag 'ellipsis' found using _get_type_name() does not match any "
+            "of the expected tags: 'list', 'dict', 'str', 'int', 'float', 'bool', "
+            "'NoneType'",
+            'type': 'union_tag_invalid',
+            'url': 'https://errors.pydantic.dev/2.4/v/union_tag_invalid',
+        }
+    ]