feat(django_getter): use function cache to increase performance

ninja/schema.py

@@ -18,14 +18,15 @@ def resolve_name(obj):
 
 """
 
+from __future__ import annotations
+
 import warnings
+from functools import partial
 from typing import (
     Any,
     Callable,
-    Dict,
-    Type,
+    ClassVar,
     TypeVar,
-    Union,
     no_type_check,
 )
 
@@ -39,6 +40,7 @@ def resolve_name(obj):
 from pydantic.json_schema import GenerateJsonSchema, JsonSchemaValue
 from typing_extensions import dataclass_transform
 
+from ninja.constants import NOT_SET
 from ninja.signature.utils import get_args_names, has_kwargs
 from ninja.types import DictStrAny
 
@@ -50,45 +52,68 @@ def resolve_name(obj):
 S = TypeVar("S", bound="Schema")
 
 
+def dict_getter(key: str, obj: DjangoGetter) -> Any:
+    if key not in obj._obj:
+        raise AttributeError(key)
+    return obj._obj[key]
+
+
+def attr_getter(key: str, obj: DjangoGetter) -> Any:
+    try:
+        return Variable(key).resolve(obj._obj)
+    except VariableDoesNotExist as e:
+        raise AttributeError(key) from e
+
+
+def resolver(resolve_func: Callable, _: str, obj: DjangoGetter) -> Any:
+    return resolve_func(getter=obj)
+
+
+def get_attr(key: str, obj: DjangoGetter) -> Any:
+    return getattr(obj._obj, key)
+
+
 class DjangoGetter:
-    __slots__ = ("_obj", "_schema_cls", "_context", "__dict__")
+    __slots__ = ("_obj", "_schema_cls", "_context", "__dict__", "_cache_key")
+    _cache: ClassVar[dict[str, Callable]] = {}
 
-    def __init__(self, obj: Any, schema_cls: Type[S], context: Any = None):
+    def __init__(self, obj: Any, schema_cls: type[S], context: Any = None) -> None:
         self._obj = obj
         self._schema_cls = schema_cls
         self._context = context
+        self._cache_key = f"{self._schema_cls.__module__}.{self._schema_cls.__name__}.{self._obj.__class__.__name__}"
 
     def __getattr__(self, key: str) -> Any:
-        # if key.startswith("__pydantic"):
-        #     return getattr(self._obj, key)
-
-        resolver = self._schema_cls._ninja_resolvers.get(key)
-        if resolver:
-            value = resolver(getter=self)
-        else:
-            if isinstance(self._obj, dict):
-                if key not in self._obj:
-                    raise AttributeError(key)
-                value = self._obj[key]
-            else:
-                try:
-                    value = getattr(self._obj, key)
-                except AttributeError:
-                    try:
-                        # value = attrgetter(key)(self._obj)
-                        value = Variable(key).resolve(self._obj)
-                        # TODO: Variable(key) __init__ is actually slower than
-                        #       Variable.resolve - so it better be cached
-                    except VariableDoesNotExist as e:
-                        raise AttributeError(key) from e
+        cache_key = f"{self._cache_key}.{key}"
+        if cache_key in DjangoGetter._cache:
+            # Use cached function, if available.
+            value = DjangoGetter._cache[cache_key](key, self)
+            return self._convert_result(value)
+
+        stored_resolver = self._schema_cls._ninja_resolvers.get(key)
+        if stored_resolver:
+            # Use resolver when provided for this key.
+            value = stored_resolver(getter=self)
+            # bind resolver of this key to the _cache
+            DjangoGetter._cache[cache_key] = partial(resolver, stored_resolver)
+            return self._convert_result(value)
+
+        if isinstance(self._obj, dict):
+            # Use dict lookup, faster than getattr
+            value = dict_getter(key, self)
+            DjangoGetter._cache[cache_key] = dict_getter
+            return self._convert_result(value)
+
+        value = getattr(self._obj, key, NOT_SET)
+        if value is not NOT_SET:
+            # If getattr worked, use that.
+            DjangoGetter._cache[cache_key] = get_attr
+            return self._convert_result(value)
+        # Finally, fallback to attr_getter
+        value = attr_getter(key, self)
+        DjangoGetter._cache[cache_key] = attr_getter
         return self._convert_result(value)
 
-    # def get(self, key: Any, default: Any = None) -> Any:
-    #     try:
-    #         return self[key]
-    #     except KeyError:
-    #         return default
-
     def _convert_result(self, result: Any) -> Any:
         if isinstance(result, Manager):
             return list(result.all())
@@ -116,7 +141,7 @@ class Resolver:
     _func: Any
     _takes_context: bool
 
-    def __init__(self, func: Union[Callable, staticmethod]):
+    def __init__(self, func: Callable | staticmethod):
         if isinstance(func, staticmethod):
             self._static = True
             self._func = func.__func__
@@ -139,25 +164,10 @@ def __call__(self, getter: DjangoGetter) -> Any:
         )  # pragma: no cover
         # return self._func(self._fake_instance(getter), getter._obj)
 
-    # def _fake_instance(self, getter: DjangoGetter) -> "Schema":
-    #     """
-    #     Generate a partial schema instance that can be used as the ``self``
-    #     attribute of resolver functions.
-    #     """
-
-    #     class PartialSchema(Schema):
-    #         def __getattr__(self, key: str) -> Any:
-    #             value = getattr(getter, key)
-    #             field = getter._schema_cls.model_fields[key]
-    #             value = field.validate(value, values={}, loc=key, cls=None)[0]
-    #             return value
-
-    #     return PartialSchema()
-
 
 @dataclass_transform(kw_only_default=True, field_specifiers=(Field,))
 class ResolverMetaclass(ModelMetaclass):
-    _ninja_resolvers: Dict[str, Resolver]
+    _ninja_resolvers: dict[str, Resolver]
 
     @no_type_check
     def __new__(cls, name, bases, namespace, **kwargs):
@@ -228,7 +238,7 @@ def _run_root_validator(
         return handler(values)
 
     @classmethod
-    def from_orm(cls: Type[S], obj: Any, **kw: Any) -> S:
+    def from_orm(cls: type[S], obj: Any, **kw: Any) -> S:
         return cls.model_validate(obj, **kw)
 
     def dict(self, *a: Any, **kw: Any) -> DictStrAny: