Finish hints for cache module

Author: adamchainz

src/django_mysql/cache.py

@@ -19,6 +19,7 @@
 from django.core.cache.backends.base import default_key_func
 from django.db import connections
 from django.db import router
+from django.db.models import Model
 from django.utils.encoding import force_bytes
 from django.utils.module_loading import import_string
 
@@ -62,7 +63,9 @@ def __init__(self, table: str, params: dict[str, Any]) -> None:
         super().__init__(params)
         self._table = table
 
-        class CacheEntry:
+        CacheEntry: type[Model]  # force Mypy to accept duck typing
+
+        class CacheEntry:  # type: ignore [no-redef]
             _meta = Options(table)
 
         self.cache_model_class = CacheEntry
@@ -183,7 +186,7 @@ def get_many(
         self, keys: Iterable[str], version: int | None = None
     ) -> dict[str, Any]:
         made_key_to_key = {self.make_key(key, version=version): key for key in keys}
-        made_keys = list(made_key_to_key.keys())
+        made_keys: list[Any] = list(made_key_to_key.keys())
         for key in made_keys:
             self.validate_key(key)
 
@@ -266,7 +269,7 @@ def _base_set(
                 return True
             else:  # mode = 'add'
                 # Use a special code in the add query for "did insert"
-                insert_id = cursor.lastrowid
+                insert_id: int = cursor.lastrowid
                 return insert_id != 444
 
     _set_many_query = collapse_spaces(
@@ -416,7 +419,8 @@ def _base_delta(
                 raise ValueError("Key '%s' not found, or not an integer" % key)
 
             # New value stored in insert_id
-            return cursor.lastrowid
+            result: int = cursor.lastrowid
+            return result
 
     # Looks a bit tangled to turn the blob back into an int for updating, but
     # it works. Stores the new value for insert_id() with LAST_INSERT_ID
@@ -448,7 +452,7 @@ def touch(
         db = router.db_for_write(self.cache_model_class)
         table = connections[db].ops.quote_name(self._table)
         with connections[db].cursor() as cursor:
-            affected_rows = cursor.execute(
+            affected_rows: int = cursor.execute(
                 self._touch_query.format(table=table), [exp, key, self._now()]
             )
         return affected_rows > 0
@@ -612,18 +616,20 @@ def delete_with_prefix(self, prefix: str, version: int | None = None) -> int:
         prefix = self.make_key(prefix + "%", version=version)
 
         with connections[db].cursor() as cursor:
-            return cursor.execute(
+            result: int = cursor.execute(
                 """DELETE FROM {table}
                    WHERE cache_key LIKE %s""".format(
                     table=table
                 ),
                 (prefix,),
             )
+            return result
 
     def cull(self) -> int:
         db = router.db_for_write(self.cache_model_class)
         table = connections[db].ops.quote_name(self._table)
 
+        num_deleted: int
         with connections[db].cursor() as cursor:
             # First, try just deleting expired keys
             num_deleted = cursor.execute(