From e2e4488bd0922e13767da1ded012ad2a910409c5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=B6ren=20Oldag?= <soeren.oldag@kiwi.ki>
Date: Mon, 15 May 2023 15:56:15 +0200
Subject: [PATCH] Allow to create request scopes outside of the middleware

---
 fastapi_injector/__init__.py      |  2 ++
 fastapi_injector/request_scope.py | 42 ++++++++++++++++++++++++-------
 tests/test_request_scope.py       | 23 +++++++++++++++++
 3 files changed, 58 insertions(+), 9 deletions(-)

diff --git a/fastapi_injector/__init__.py b/fastapi_injector/__init__.py
index 98260c7..14784eb 100644
--- a/fastapi_injector/__init__.py
+++ b/fastapi_injector/__init__.py
@@ -9,6 +9,7 @@
 from fastapi_injector.request_scope import (
     InjectorMiddleware,
     RequestScope,
+    RequestScopeFactory,
     request_scope,
 )
 
@@ -20,5 +21,6 @@
     "InjectorNotAttached",
     "request_scope",
     "RequestScope",
+    "RequestScopeFactory",
     "InjectorMiddleware",
 ]
diff --git a/fastapi_injector/request_scope.py b/fastapi_injector/request_scope.py
index 0fa015e..99c1ef3 100644
--- a/fastapi_injector/request_scope.py
+++ b/fastapi_injector/request_scope.py
@@ -1,8 +1,17 @@
 import uuid
+from contextlib import contextmanager
 from contextvars import ContextVar
 from typing import Any, Dict, Type
 
-from injector import Injector, InstanceProvider, Provider, Scope, ScopeDecorator, T
+from injector import (
+    Inject,
+    Injector,
+    InstanceProvider,
+    Provider,
+    Scope,
+    ScopeDecorator,
+    T,
+)
 from starlette.types import Receive, Send
 
 from fastapi_injector.exceptions import RequestScopeError
@@ -66,6 +75,27 @@ def clear_key(self, key: uuid.UUID) -> None:
 request_scope = ScopeDecorator(RequestScope)
 
 
+class RequestScopeFactory:
+    """
+    Allows to create request scopes.
+    """
+
+    def __init__(self, request_scope_instance: Inject[RequestScope]) -> None:
+        self.request_scope_instance = request_scope_instance
+
+    @contextmanager
+    def create_scope(self):
+        """Creates a new request scope within dependencies are cached."""
+        rid = uuid.uuid4()
+        rid_ctx = _request_id_ctx.set(rid)
+        self.request_scope_instance.add_key(rid)
+        try:
+            yield
+        finally:
+            self.request_scope_instance.clear_key(rid)
+            _request_id_ctx.reset(rid_ctx)
+
+
 class InjectorMiddleware:
     """
     Middleware that enables request-scoped injection through ContextVar-based cache.
@@ -73,18 +103,12 @@ class InjectorMiddleware:
 
     def __init__(self, app, injector: Injector) -> None:
         self.app = app
-        self.request_scope_instance = injector.get(RequestScope)
+        self.request_scope_factory = injector.get(RequestScopeFactory)
 
     async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
         """
         Add an identifier to the request
         that can be used retrieve scoped dependencies.
         """
-        rid = uuid.uuid4()
-        rid_ctx = _request_id_ctx.set(rid)
-        self.request_scope_instance.add_key(rid)
-        try:
+        with self.request_scope_factory.create_scope():
             await self.app(scope, receive, send)
-        finally:
-            self.request_scope_instance.clear_key(rid)
-            _request_id_ctx.reset(rid_ctx)
diff --git a/tests/test_request_scope.py b/tests/test_request_scope.py
index 8c28b4b..c70197d 100644
--- a/tests/test_request_scope.py
+++ b/tests/test_request_scope.py
@@ -14,6 +14,7 @@
     Injected,
     InjectorMiddleware,
     RequestScope,
+    RequestScopeFactory,
     attach_injector,
     request_scope,
 )
@@ -209,3 +210,25 @@ def get_root(
         await client.get("/")
 
     assert len(scope_instance.cache) == 0
+
+
+async def test_caches_instances_with_scope_factory():
+    class DummyInterface:
+        pass
+
+    class DummyImpl:
+        pass
+
+    inj = Injector()
+    inj.binder.bind(DummyInterface, to=DummyImpl, scope=request_scope)
+
+    factory = inj.get(RequestScopeFactory)
+
+    with factory.create_scope():
+        dummy1 = inj.get(DummyInterface)
+        dummy2 = inj.get(DummyInterface)
+        assert dummy1 is dummy2
+
+    with factory.create_scope():
+        dummy3 = inj.get(DummyInterface)
+        assert dummy1 is not dummy3