Change how Private is implemented to better support type checkers

RELEASE.md

@@ -0,0 +1,4 @@
+Release type: minor
+
+This release changes how `strawberry.Private` is implemented to
+improve support for type checkers.

strawberry/experimental/pydantic/utils.py

@@ -2,7 +2,7 @@
 from typing import Any, List, Type
 
 from strawberry.experimental.pydantic.exceptions import UnregisteredTypeException
-from strawberry.private import Private
+from strawberry.private import is_private
 from strawberry.utils.typing import (
     get_list_annotation,
     get_optional_annotation,
@@ -30,7 +30,9 @@ def get_strawberry_type_from_model(type_: Any):
 
 def get_private_fields(cls: Type) -> List[dataclasses.Field]:
     private_fields: List[dataclasses.Field] = []
+
     for field in dataclasses.fields(cls):
-        if isinstance(field.type, Private):
+        if is_private(field.type):
             private_fields.append(field)
+
     return private_fields

strawberry/ext/mypy_plugin.py

@@ -78,13 +78,6 @@ def strawberry_field_hook(ctx: FunctionContext) -> Type:
     return AnyType(TypeOfAny.special_form)
 
 
-def private_type_analyze_callback(ctx: AnalyzeTypeContext) -> Type:
-    type_name = ctx.type.args[0]
-    type_ = ctx.api.analyze_type(type_name)
-
-    return type_
-
-
 def _get_named_type(name: str, api: SemanticAnalyzerPluginInterface):
     if "." in name:
         return api.named_type_or_none(name)  # type: ignore
@@ -638,9 +631,6 @@ def get_type_analyze_hook(self, fullname: str):
         if self._is_strawberry_lazy_type(fullname):
             return lazy_type_analyze_callback
 
-        if self._is_strawberry_private(fullname):
-            return private_type_analyze_callback
-
         return None
 
     def get_class_decorator_hook(
@@ -682,11 +672,6 @@ def _is_strawberry_enum(self, fullname: str) -> bool:
     def _is_strawberry_lazy_type(self, fullname: str) -> bool:
         return fullname == "strawberry.lazy_type.LazyType"
 
-    def _is_strawberry_private(self, fullname: str) -> bool:
-        return fullname == "strawberry.private.Private" or fullname.endswith(
-            "strawberry.Private"
-        )
-
     def _is_strawberry_decorator(self, fullname: str) -> bool:
         if any(
             strawberry_decorator in fullname

strawberry/private.py

@@ -1,27 +1,31 @@
-class Private:
-    """Represent a private field that won't be converted into a GraphQL field
+from typing import TypeVar
 
-    Example:
+from typing_extensions import Annotated, get_args, get_origin
 
-    >>> import strawberry
-    >>> @strawberry.type
-    ... class User:
-    ...     name: str
-    ...     age: strawberry.Private[int]
-    """
 
-    __slots__ = ("type",)
+class StrawberryPrivate:
+    ...
 
-    def __init__(self, type):
-        self.type = type
 
-    def __repr__(self):
-        if isinstance(self.type, type):
-            type_name = self.type.__name__
-        else:
-            # typing objects, e.g. List[int]
-            type_name = repr(self.type)
-        return f"strawberry.Private[{type_name}]"
+T = TypeVar("T")
 
-    def __class_getitem__(cls, type):
-        return Private(type)
+Private = Annotated[T, StrawberryPrivate()]
+Private.__doc__ = """Represent a private field that won't be converted into a GraphQL field
+
+Example:
+
+>>> import strawberry
+>>> @strawberry.type
+... class User:
+...     name: str
+...     age: strawberry.Private[int]
+"""
+
+
+def is_private(type_: object) -> bool:
+    if get_origin(type_) is Annotated:
+        return any(
+            isinstance(argument, StrawberryPrivate) for argument in get_args(type_)
+        )
+
+    return False

strawberry/types/type_resolver.py

@@ -9,7 +9,7 @@
     PrivateStrawberryFieldError,
 )
 from strawberry.field import StrawberryField
-from strawberry.private import Private
+from strawberry.private import is_private
 
 from ..arguments import UNSET
 
@@ -81,7 +81,7 @@ class if one is not set by either using an explicit strawberry.field(name=...) o
 
         if isinstance(field, StrawberryField):
             # Check that the field type is not Private
-            if isinstance(field.type, Private):
+            if is_private(field.type):
                 raise PrivateStrawberryFieldError(field.python_name, cls.__name__)
 
             # Check that default is not set if a resolver is defined
@@ -125,7 +125,7 @@ class if one is not set by either using an explicit strawberry.field(name=...) o
         # Create a StrawberryField for fields that didn't use strawberry.field
         else:
             # Only ignore Private fields that weren't defined using StrawberryFields
-            if isinstance(field.type, Private):
+            if is_private(field.type):
                 continue
 
             field_type = field.type

tests/pyright/test_private.py

@@ -0,0 +1,50 @@
+from .utils import Result, requires_pyright, run_pyright, skip_on_windows
+
+
+pytestmark = [skip_on_windows, requires_pyright]
+
+
+CODE = """
+import strawberry
+
+
+@strawberry.type
+class User:
+    name: str
+    age: strawberry.Private[int]
+
+
+patrick = User(name="Patrick", age=1)
+User(n="Patrick")
+
+reveal_type(patrick.name)
+reveal_type(patrick.age)
+"""
+
+
+def test_pyright():
+    results = run_pyright(CODE)
+
+    assert results == [
+        Result(
+            type="error",
+            message='No parameter named "n" (reportGeneralTypeIssues)',
+            line=12,
+            column=6,
+        ),
+        Result(
+            type="error",
+            message=(
+                "Arguments missing for parameters "
+                '"name", "age" (reportGeneralTypeIssues)'
+            ),
+            line=12,
+            column=1,
+        ),
+        Result(
+            type="info", message='Type of "patrick.name" is "str"', line=14, column=13
+        ),
+        Result(
+            type="info", message='Type of "patrick.age" is "int"', line=15, column=13
+        ),
+    ]