Infer root type from Annotated (but toss away the rest of the annotat…

…ion)

pydantic/fields.py

@@ -28,6 +28,7 @@
 from .errors import NoneIsNotAllowedError
 from .types import Json, JsonWrapper
 from .typing import (
+    Annotated,
     Callable,
     ForwardRef,
     NoArgAnyCallable,
@@ -424,6 +425,10 @@ def _type_analysis(self) -> None:  # noqa: C901 (ignore complexity)
             if isinstance(self.type_, type) and isinstance(None, self.type_):
                 self.allow_none = True
             return
+        if origin is Annotated:
+            self.type_ = get_args(self.type_)[0]
+            self._type_analysis()
+            return
         if origin is Callable:
             return
         if origin is Union:

pydantic/typing.py

@@ -127,6 +127,17 @@ def get_args(tp: Type[Any]) -> Tuple[Any, ...]:
         # the fallback is needed for the same reasons as `get_origin` (see above)
         return typing_get_args(tp) or getattr(tp, '__args__', ()) or generic_get_args(tp)
 
+if sys.version_info < (3, 9):
+    if TYPE_CHECKING:
+        from typing_extensions import Annotated
+    else:  # due to different mypy warnings raised during CI for python 3.7 and 3.8
+        try:
+            from typing_extensions import Annotated
+        except ImportError:
+            Annotated = None
+else:
+    from typing import Annotated
+
 
 if TYPE_CHECKING:
     from .fields import ModelField