Use BSON preconf stage and store response values under top-level keys, so created_at attribute is compatible with TTL index

3 files changed, 25 insertions, 10 deletions

diff --git a/requests_cache/serializers/__init__.py b/requests_cache/serializers/__init__.py
index dc78489..91c5e4c 100644
--- a/requests_cache/serializers/__init__.py
+++ b/requests_cache/serializers/__init__.py
@@ -19,6 +19,7 @@ __all__ = [
     'SerializerPipeline',
     'Stage',
     'bson_serializer',
+    'dict_serializer',
     'json_serializer',
     'pickle_serializer',
     'safe_pickle_serializer',
@@ -29,7 +30,6 @@ __all__ = [
 
 SERIALIZERS = {
     'bson': bson_serializer,
-    'dict': dict_serializer,
     'json': json_serializer,
     'pickle': pickle_serializer,
     'yaml': yaml_serializer,
diff --git a/requests_cache/serializers/cattrs.py b/requests_cache/serializers/cattrs.py
index e0bde94..da7fd79 100644
--- a/requests_cache/serializers/cattrs.py
+++ b/requests_cache/serializers/cattrs.py
@@ -28,8 +28,8 @@ class CattrStage(Stage):
     on its own, or as a stage within a :py:class:`.SerializerPipeline`.
     """
 
-    def __init__(self, factory: Callable[..., GenConverter] = None):
-        self.converter = init_converter(factory)
+    def __init__(self, factory: Callable[..., GenConverter] = None, **kwargs):
+        self.converter = init_converter(factory, **kwargs)
 
     def dumps(self, value: CachedResponse) -> Dict:
         if not isinstance(value, CachedResponse):
@@ -42,14 +42,22 @@ class CattrStage(Stage):
         return self.converter.structure(value, cl=CachedResponse)
 
 
-def init_converter(factory: Callable[..., GenConverter] = None):
-    """Make a converter to structure and unstructure nested objects within a :py:class:`.CachedResponse`"""
+def init_converter(factory: Callable[..., GenConverter] = None, convert_datetime: bool = True):
+    """Make a converter to structure and unstructure nested objects within a
+    :py:class:`.CachedResponse`
+
+    Args:
+        factory: An optional factory function that returns a ``cattrs`` converter
+        convert_datetime: May be set to ``False`` for pre-configured converters that already have
+            datetime support
+    """
     factory = factory or GenConverter
     converter = factory(omit_if_default=True)
 
     # Convert datetimes to and from iso-formatted strings
-    converter.register_unstructure_hook(datetime, lambda obj: obj.isoformat() if obj else None)  # type: ignore
-    converter.register_structure_hook(datetime, _to_datetime)
+    if convert_datetime:
+        converter.register_unstructure_hook(datetime, lambda obj: obj.isoformat() if obj else None)  # type: ignore
+        converter.register_structure_hook(datetime, _to_datetime)
 
     # Convert timedeltas to and from float values in seconds
     converter.register_unstructure_hook(timedelta, lambda obj: obj.total_seconds() if obj else None)  # type: ignore
@@ -66,6 +74,10 @@ def init_converter(factory: Callable[..., GenConverter] = None):
     converter.register_structure_hook(HTTPHeaderDict, lambda obj, cls: HTTPHeaderDict(obj))
 
     # Tell cattrs to resolve forward references (required for CachedResponse.history)
+    converter.register_unstructure_hook_func(
+        lambda cls: cls.__class__ is ForwardRef,
+        lambda obj, cls=None: converter.unstructure(obj, cls.__forward_value__ if cls else None),
+    )
     converter.register_structure_hook_func(
         lambda cls: cls.__class__ is ForwardRef,
         lambda obj, cls: converter.structure(obj, cls.__forward_value__),
diff --git a/requests_cache/serializers/preconf.py b/requests_cache/serializers/preconf.py
index 1236c44..b0ad069 100644
--- a/requests_cache/serializers/preconf.py
+++ b/requests_cache/serializers/preconf.py
@@ -22,10 +22,11 @@ from .cattrs import CattrStage
 from .pipeline import SerializerPipeline, Stage
 
 
-def make_stage(preconf_module: str):
+def make_stage(preconf_module: str, **kwargs):
     """Create a preconf serializer stage from a module name, if dependencies are installed"""
     try:
-        return CattrStage(import_module(preconf_module).make_converter)
+        factory = import_module(preconf_module).make_converter
+        return CattrStage(factory, **kwargs)
     except ImportError as e:
         return get_placeholder_class(e)
 
@@ -33,7 +34,9 @@ def make_stage(preconf_module: str):
 # Pre-serialization stages
 base_stage = CattrStage()  #: Base stage for all serializer pipelines
 utf8_encoder = Stage(dumps=str.encode, loads=lambda x: x.decode())  #: Encode to bytes
-bson_preconf_stage = make_stage('cattr.preconf.bson')  #: Pre-serialization steps for BSON
+bson_preconf_stage = make_stage(
+    'cattr.preconf.bson', convert_datetime=False
+)  #: Pre-serialization steps for BSON
 json_preconf_stage = make_stage('cattr.preconf.json')  #: Pre-serialization steps for JSON
 msgpack_preconf_stage = make_stage('cattr.preconf.msgpack')  #: Pre-serialization steps for msgpack
 orjson_preconf_stage = make_stage('cattr.preconf.orjson')  #: Pre-serialization steps for orjson