Fix mypy errors

dlt/destinations/impl/filesystem/configuration.py

@@ -1,23 +1,20 @@
 import dataclasses
 
-from typing import Any, Callable, Dict, Final, Type, Optional, TypeAlias, Union
+from typing import Any, Callable, Dict, Final, Type, Optional, Union
 
-
-from pendulum.datetime import DateTime
 from dlt.common.configuration import configspec, resolve_type
 from dlt.common.destination.reference import (
     CredentialsConfiguration,
     DestinationClientStagingConfiguration,
 )
 from dlt.common.storages import FilesystemConfiguration
+from pendulum.datetime import DateTime
+from typing_extensions import TypeAlias
 
 TCurrentDatetimeCallback: TypeAlias = Callable[[], DateTime]
 """A callback which should return current datetime"""
 
-TDatetimeFormatterCallback: TypeAlias = Callable[[DateTime], str]
-"""A callback which is responsible to format datetime"""
-
-TDatetimeFormat: TypeAlias = Union[str, TDatetimeFormatterCallback]
+TDatetimeFormat: TypeAlias = str
 """Datetime format or formatter callback"""
 
 TLayoutParamCallback: TypeAlias = Callable[[str, str, str, str, str, DateTime], str]
@@ -27,12 +24,12 @@
 
 
 @configspec
-class FilesystemDestinationClientConfiguration(
+class FilesystemDestinationClientConfiguration(  # type: ignore[misc]
     FilesystemConfiguration, DestinationClientStagingConfiguration
-):  # type: ignore[misc]
-    destination_type: Final[str] = dataclasses.field(
+):
+    destination_type: Final[str] = dataclasses.field(  # type: ignore
         default="filesystem", init=False, repr=False, compare=False
-    )  # type: ignore
+    )
     current_datetime: Optional[Union[DateTime, TCurrentDatetimeCallback]] = None
     datetime_format: Optional[TDatetimeFormat] = None
     extra_params: Optional[Dict[str, Union[str, TLayoutParamCallback]]] = None
@@ -41,8 +38,8 @@ class FilesystemDestinationClientConfiguration(
     def resolve_credentials_type(self) -> Type[CredentialsConfiguration]:
         # use known credentials or empty credentials for unknown protocol
         return (
-            self.PROTOCOL_CREDENTIALS.get(self.protocol) or Optional[CredentialsConfiguration]
-        )  # type: ignore[return-value]
+            self.PROTOCOL_CREDENTIALS.get(self.protocol) or Optional[CredentialsConfiguration]  # type: ignore[return-value]
+        )
 
     def on_resolved(self) -> None:
         """Resolve configuration for filesystem destination
@@ -56,22 +53,8 @@ def on_resolved(self) -> None:
             * datetime_format,
             * extra_params
         """
-        # If current_datetime is a callable
-        # then we need to inspect it's return type
-        # if return type is not DateTime
-        # then call it and check it's instance
-        # if it is not DateTime then exit.
-        current_datetime = self.kwargs.get("current_datetime", self.current_datetime)
-        if current_datetime is not None:
-            if callable(current_datetime):
-                result = current_datetime()
-                if isinstance(result, DateTime):
-                    self.current_datetime = result
-                else:
-                    raise RuntimeError(
-                        "current_datetime was passed as callable but "
-                        "didn't return any instance of pendulum.DateTime"
-                    )
+        if current_datetime := self.kwargs.get("current_datetime"):
+            self.current_datetime = current_datetime
 
         datetime_format = self.kwargs.get("datetime_format", self.datetime_format)
         if datetime_format is not None:

dlt/destinations/impl/filesystem/layout.py

@@ -1,6 +1,6 @@
 import re
 from types import TracebackType
-from typing import Any, Dict, List, Optional, Self, Sequence, Set, Type
+from typing import Any, Dict, List, Optional, Sequence, Set, Type
 
 import pendulum
 
@@ -9,6 +9,7 @@
 from dlt.destinations.impl.filesystem.configuration import (
     FilesystemDestinationClientConfiguration,
 )
+from typing_extensions import Self
 
 # TODO: ensure layout only has supported placeholders
 SUPPORTED_PLACEHOLDERS = {
@@ -42,7 +43,7 @@ def __init__(
         self.job_info = job_info
         self.load_id = load_id
         self.schema_name = schema_name
-        self._params = {}
+        self._params: Dict[str, Any] = {}
 
         self.table_name = None
         self.file_id = None
@@ -85,8 +86,25 @@ def params(self) -> Optional[Dict[str, Any]]:
                     "ext": self.file_format,
                 }
             )
+        # If current_datetime is a callable
+        # then we need to inspect it's return type
+        # if return type is not DateTime
+        # then call it and check it's instance
+        # if it is not DateTime then exit.
+        if self.config.current_datetime is not None:
+            if callable(self.config.current_datetime):
+                result = self.config.current_datetime()
+                if isinstance(result, pendulum.DateTime):
+                    self.current_datetime = result
+                else:
+                    raise RuntimeError(
+                        "current_datetime was passed as callable but "
+                        "didn't return any instance of pendulum.DateTime"
+                    )
+        else:
+            self.config.current_datetime = pendulum.now()
 
-        now = self.config.current_datetime or pendulum.now()
+        now: pendulum.DateTime = self.config.current_datetime  # type: ignore[assignment]
         for key, value in self.config.extra_params.items():
             if callable(value):
                 self._params[key] = value(
@@ -206,7 +224,7 @@ def get_table_prefix_layout(
     ) as layout:
         # fail if table name is not defined
         if "table_name" not in layout.placeholders:
-            raise CantExtractTablePrefix(layout, "{table_name} placeholder not found. ")
+            raise CantExtractTablePrefix(config.layout, "{table_name} placeholder not found. ")
 
     table_name_index = layout.layout_placeholders.index("table_name")