Typing cleanup

- Compatibility with older Python versions
  - use `Optional` and `Union` instead of `... | None` and `a | b`
  - use `typing_extensions.Protocol` instead of `typing.Protocol`
  - use `typing.Dict`, `typing.List`, etc. instead of the concrete types.

- Fix backend `.get()` annotations; not all were marked as `Optional[str]`
- Don't return anything from `Backend.set()` methods.
- The `Coder.decode_as_type()` type parameter must be a type to be
  compatible with `ModelField(..., type_=...)`.
- Clean up `Optional[]` use, remove where it is not needed.
- Clean up variable use in decorator, keeping the raw cached value
  separate from the return value from the wrapped endpoint.
- Annotate the wrapper as returning either the original type _or_ a
  Response (returning a 304 Not Modified response).
- Clean up small edge-case where `response` could be `None`.
- Correct type annotation on `JsonCoder.decode()` to match `Coder.decode()`.

examples/in_memory/main.py

@@ -1,3 +1,5 @@
+from typing import Dict, Optional
+
 import pendulum
 import uvicorn
 from fastapi import FastAPI
@@ -84,9 +86,9 @@ app.get("/method")(cache(namespace="test")(instance.handler_method))
 # cache a Pydantic model instance; the return type annotation is required in this case
 class Item(BaseModel):
     name: str
-    description: str | None = None
+    description: Optional[str] = None
     price: float
-    tax: float | None = None
+    tax: Optional[float] = None
 
 
 @app.get("/pydantic_instance")
@@ -110,7 +112,7 @@ async def uncached_put():
 @cache(namespace="test", expire=5, injected_dependency_namespace="monty_python")
 def namespaced_injection(
     __fastapi_cache_request: int = 42, __fastapi_cache_response: int = 17
-) -> dict[str, int]:
+) -> Dict[str, int]:
     return {
         "__fastapi_cache_request": __fastapi_cache_request,
         "__fastapi_cache_response": __fastapi_cache_response,

fastapi_cache/coder.py

@@ -10,10 +10,10 @@ from pydantic import BaseConfig, ValidationError, fields
 from starlette.responses import JSONResponse
 from starlette.templating import _TemplateResponse as TemplateResponse
 
-_T = TypeVar("_T")
+_T = TypeVar("_T", bound=type)
 
 
-CONVERTERS: dict[str, Callable[[str], Any]] = {
+CONVERTERS: Dict[str, Callable[[str], Any]] = {
     "date": lambda x: pendulum.parse(x, exact=True),
     "datetime": lambda x: pendulum.parse(x, exact=True),
     "decimal": Decimal,

fastapi_cache/decorator.py

@@ -2,7 +2,7 @@ import logging
 import sys
 from functools import wraps
 from inspect import Parameter, Signature, isawaitable, iscoroutinefunction
-from typing import Awaitable, Callable, Optional, Type, TypeVar
+from typing import Awaitable, Callable, List, Optional, Type, TypeVar, Union
 
 if sys.version_info >= (3, 10):
     from typing import ParamSpec
@@ -36,7 +36,7 @@ def _augment_signature(signature: Signature, *extra: Parameter) -> Signature:
     return signature.replace(parameters=[*parameters, *extra, *variadic_keyword_params])
 
 
-def _locate_param(sig: Signature, dep: Parameter, to_inject: list[Parameter]) -> Parameter:
+def _locate_param(sig: Signature, dep: Parameter, to_inject: List[Parameter]) -> Parameter:
     """Locate an existing parameter in the decorated endpoint
 
     If not found, returns the injectable parameter, and adds it to the to_inject list.
@@ -56,9 +56,9 @@ def cache(
     expire: Optional[int] = None,
     coder: Optional[Type[Coder]] = None,
     key_builder: Optional[KeyBuilder] = None,
-    namespace: Optional[str] = "",
+    namespace: str = "",
     injected_dependency_namespace: str = "__fastapi_cache",
-) -> Callable[[Callable[P, Awaitable[R]]], Callable[P, Awaitable[R]]]:
+) -> Callable[[Callable[P, Awaitable[R]]], Callable[P, Awaitable[Union[R, Response]]]]:
     """
     cache all function
     :param namespace:
@@ -80,7 +80,7 @@ def cache(
         kind=Parameter.KEYWORD_ONLY,
     )
 
-    def wrapper(func: Callable[P, Awaitable[R]]) -> Callable[P, Awaitable[R]]:
+    def wrapper(func: Callable[P, Awaitable[R]]) -> Callable[P, Awaitable[Union[R, Response]]]:
         # get_typed_signature ensures that any forward references are resolved first
         wrapped_signature = get_typed_signature(func)
         to_inject: list[Parameter] = []
@@ -89,7 +89,7 @@ def cache(
         return_type = get_typed_return_annotation(func)
 
         @wraps(func)
-        async def inner(*args: P.args, **kwargs: P.kwargs) -> R:
+        async def inner(*args: P.args, **kwargs: P.kwargs) -> Union[R, Response]:
             nonlocal coder
             nonlocal expire
             nonlocal key_builder
@@ -139,15 +139,15 @@ def cache(
                 cache_key = await cache_key
 
             try:
-                ttl, ret = await backend.get_with_ttl(cache_key)
+                ttl, cached = await backend.get_with_ttl(cache_key)
             except Exception:
                 logger.warning(
                     f"Error retrieving cache key '{cache_key}' from backend:", exc_info=True
                 )
-                ttl, ret = 0, None
+                ttl, cached = 0, None
             if not request:
-                if ret is not None:
-                    return coder.decode_as_type(ret, type_=return_type)
+                if cached is not None:
+                    return coder.decode_as_type(cached, type_=return_type)
                 ret = await ensure_async_func(*args, **kwargs)
                 try:
                     await backend.set(cache_key, coder.encode(ret), expire)
@@ -161,15 +161,15 @@ def cache(
                 return await ensure_async_func(*args, **kwargs)
 
             if_none_match = request.headers.get("if-none-match")
-            if ret is not None:
+            if cached is not None:
                 if response:
                     response.headers["Cache-Control"] = f"max-age={ttl}"
-                    etag = f"W/{hash(ret)}"
+                    etag = f"W/{hash(cached)}"
                     if if_none_match == etag:
                         response.status_code = 304
                         return response
                     response.headers["ETag"] = etag
-                return coder.decode_as_type(ret, type_=return_type)
+                return coder.decode_as_type(cached, type_=return_type)
 
             ret = await ensure_async_func(*args, **kwargs)
             encoded_ret = coder.encode(ret)
@@ -179,6 +179,7 @@ def cache(
             except Exception:
                 logger.warning(f"Error setting cache key '{cache_key}' in backend:", exc_info=True)
 
+            if response:
                 response.headers["Cache-Control"] = f"max-age={expire}"
                 etag = f"W/{hash(encoded_ret)}"
                 response.headers["ETag"] = etag

fastapi_cache/key_builder.py

@@ -1,5 +1,5 @@
 import hashlib
-from typing import Any, Callable, Optional
+from typing import Any, Callable, Dict, Optional, Tuple
 
 from starlette.requests import Request
 from starlette.responses import Response
@@ -10,8 +10,8 @@ def default_key_builder(
     namespace: str = "",
     request: Optional[Request] = None,
     response: Optional[Response] = None,
-    args: Optional[tuple[Any, ...]] = None,
-    kwargs: Optional[dict[str, Any]] = None,
+    args: Optional[Tuple[Any, ...]] = None,
+    kwargs: Optional[Dict[str, Any]] = None,
 ) -> str:
     cache_key = hashlib.md5(  # nosec:B303
         f"{func.__module__}:{func.__name__}:{args}:{kwargs}".encode()

fastapi_cache/types.py

@@ -1,7 +1,8 @@
-from typing import Any, Awaitable, Callable, Optional, Protocol, Union
+from typing import Any, Awaitable, Callable, Dict, Optional, Tuple, Union
 
 from starlette.requests import Request
 from starlette.responses import Response
+from typing_extensions import Protocol
 
 
 _Func = Callable[..., Any]
@@ -15,7 +16,7 @@ class KeyBuilder(Protocol):
         *,
         request: Optional[Request] = ...,
         response: Optional[Response] = ...,
-        args: tuple[Any, ...] = ...,
-        kwargs: dict[str, Any] = ...,
+        args: Tuple[Any, ...] = ...,
+        kwargs: Dict[str, Any] = ...,
     ) -> Union[Awaitable[str], str]:
         ...

poetry.lock

@@ -304,14 +304,14 @@ crt = ["awscrt (==0.11.24)"]
 
 [[package]]
 name = "certifi"
-version = "2022.12.7"
+version = "2023.5.7"
 description = "Python package for providing Mozilla's CA Bundle."
 category = "dev"
 optional = false
 python-versions = ">=3.6"
 files = [
-    {file = "certifi-2022.12.7-py3-none-any.whl", hash = "sha256:4ad3232f5e926d6718ec31cfc1fcadfde020920e278684144551c91769c7bc18"},
-    {file = "certifi-2022.12.7.tar.gz", hash = "sha256:35824b4c3a97115964b408844d64aa14db1cc518f6562e8d7261699d1350a9e3"},
+    {file = "certifi-2023.5.7-py3-none-any.whl", hash = "sha256:c6c2e98f5c7869efca1f8916fed228dd91539f9f1b444c314c06eef02980c716"},
+    {file = "certifi-2023.5.7.tar.gz", hash = "sha256:0f0d56dc5a6ad56fd4ba36484d6cc34451e1c6548c61daad8c320169f91eddc7"},
 ]
 
 [[package]]
@@ -1099,18 +1099,18 @@ files = [
 
 [[package]]
 name = "redis"
-version = "4.5.4"
+version = "4.5.5"
 description = "Python client for Redis database and key-value store"
 category = "main"
 optional = true
 python-versions = ">=3.7"
 files = [
-    {file = "redis-4.5.4-py3-none-any.whl", hash = "sha256:2c19e6767c474f2e85167909061d525ed65bea9301c0770bb151e041b7ac89a2"},
-    {file = "redis-4.5.4.tar.gz", hash = "sha256:73ec35da4da267d6847e47f68730fdd5f62e2ca69e3ef5885c6a78a9374c3893"},
+    {file = "redis-4.5.5-py3-none-any.whl", hash = "sha256:77929bc7f5dab9adf3acba2d3bb7d7658f1e0c2f1cafe7eb36434e751c471119"},
+    {file = "redis-4.5.5.tar.gz", hash = "sha256:dc87a0bdef6c8bfe1ef1e1c40be7034390c2ae02d92dcd0c7ca1729443899880"},
 ]
 
 [package.dependencies]
-async-timeout = {version = ">=4.0.2", markers = "python_version <= \"3.11.2\""}
+async-timeout = {version = ">=4.0.2", markers = "python_full_version <= \"3.11.2\""}
 importlib-metadata = {version = ">=1.0", markers = "python_version < \"3.8\""}
 typing-extensions = {version = "*", markers = "python_version < \"3.8\""}
 
@@ -1120,21 +1120,21 @@ ocsp = ["cryptography (>=36.0.1)", "pyopenssl (==20.0.1)", "requests (>=2.26.0)"
 
 [[package]]
 name = "requests"
-version = "2.29.0"
+version = "2.30.0"
 description = "Python HTTP for Humans."
 category = "dev"
 optional = false
 python-versions = ">=3.7"
 files = [
-    {file = "requests-2.29.0-py3-none-any.whl", hash = "sha256:e8f3c9be120d3333921d213eef078af392fba3933ab7ed2d1cba3b56f2568c3b"},
-    {file = "requests-2.29.0.tar.gz", hash = "sha256:f2e34a75f4749019bb0e3effb66683630e4ffeaf75819fb51bebef1bf5aef059"},
+    {file = "requests-2.30.0-py3-none-any.whl", hash = "sha256:10e94cc4f3121ee6da529d358cdaeaff2f1c409cd377dbc72b825852f2f7e294"},
+    {file = "requests-2.30.0.tar.gz", hash = "sha256:239d7d4458afcb28a692cdd298d87542235f4ca8d36d03a15bfc128a6559a2f4"},
 ]
 
 [package.dependencies]
 certifi = ">=2017.4.17"
 charset-normalizer = ">=2,<4"
 idna = ">=2.5,<4"
-urllib3 = ">=1.21.1,<1.27"
+urllib3 = ">=1.21.1,<3"
 
 [package.extras]
 socks = ["PySocks (>=1.5.6,!=1.5.7)"]
@@ -1476,4 +1476,4 @@ redis = ["redis"]
 [metadata]
 lock-version = "2.0"
 python-versions = "^3.7"
-content-hash = "4325f045144b309e8378c02465b4e66544d28fc74751883f9a50ff391df08dbe"
+content-hash = "479b55889016688ab9b82e0a1c998ac2faaddf0807d0174b99289d02613387a8"

pyproject.toml

@@ -22,7 +22,7 @@ redis = { version = "^4.2.0rc1", optional = true }
 aiomcache = { version = "*", optional = true }
 pendulum = "*"
 aiobotocore = { version = "^1.4.1", optional = true }
-typing-extensions = { version = ">=4.1.0", markers = "python_version < \"3.10\"" }
+typing-extensions = { version = ">=4.1.0" }
 aiohttp = { version = ">=3.8.3", markers = "python_version >= \"3.11\"" }
 
 [tool.poetry.group.dev.dependencies]

tests/test_codecs.py

@@ -1,5 +1,5 @@
 from dataclasses import dataclass
-from typing import Any, Optional
+from typing import Any, Optional, Tuple
 
 import pytest
 from pydantic import BaseModel, ValidationError
@@ -46,7 +46,7 @@ def test_pickle_coder(value: Any) -> None:
     [
         (1, None),
         ("some_string", None),
-        ((1, 2), tuple[int, int]),
+        ((1, 2), Tuple[int, int]),
         ([1, 2, 3], None),
         ({"some_key": 1, "other_key": 2}, None),
         (DCItem(name="foo", price=42.0, description="some dataclass item", tax=0.2), DCItem),