added new example of filter registration

examples/custom_filter_example.py

@@ -1,4 +1,4 @@
-from typing import Union
+from typing import Any, Union
 from aiogram import Bot, Dispatcher, executor, types
 from aiogram.dispatcher.filters import BoundFilter
 from aiogram.dispatcher.handler import ctx_data
@@ -22,18 +22,16 @@ dp = Dispatcher(bot)
 class UserMiddleware(LifetimeControllerMiddleware):
     skip_patterns = ["error", "update"]
 
-    def __init__(self):
-        super(UserMiddleware, self).__init__()
-
     async def pre_process(
         self,
-        update: Union[types.Message, types.CallbackQuery],
+        obj: Union[types.Message, types.CallbackQuery],
         data: dict,
     ):
-        if update.from_user.id not in fake_db:
-            fake_db[update.from_user.id] = {"ban": False}
+        user = obj.from_user
+        if user.id not in fake_db:
+            fake_db[user.id] = {"ban": False}
 
-        data["user_in_db"] = fake_db[update.from_user.id]
+        data["user_in_db"] = fake_db[user.id]
 
 
 class BanUserFilter(BoundFilter):
@@ -44,14 +42,14 @@ class BanUserFilter(BoundFilter):
     key = "banned"
 
     def __init__(self, banned: bool):
-        if banned is False:
-            raise ValueError("filter banned cannot be False")
+        self.banned = banned
 
-    async def check(self, obj: Union[types.Message, types.CallbackQuery]):
-        data = ctx_data.get()
-        user_in_db = data["user_in_db"]
-
-        return not user_in_db["ban"]
+    async def check(self, obj: Any):
+        data: dict = ctx_data.get()
+        user_in_db = data.get("user_in_db", None)
+        if user_in_db:
+            return self.banned == user_in_db["ban"]
+        return False  # If the user is not in the database, then he cannot be banned
 
 
 class IsEvenIdFilter(BoundFilter):
@@ -70,18 +68,38 @@ class IsEvenIdFilter(BoundFilter):
         return {"is_even": bool(user_id % 2 == 0)}
 
 
+class DatabaseIsNotEmptyFilter(BoundFilter):
+    """
+    Check if the database contains the required number of records
+    """
+
+    key = "data_in_db"
+
+    def __init__(self, data_in_db: int):
+        if isinstance(data_in_db, int):
+            self.data_in_db = data_in_db
+        else:
+            raise ValueError(
+                f"filter data_in_db must be a int, not {type(data_in_db).__name__}"
+            )
+
+    async def check(self, obj: Any):
+        return len(fake_db) >= self.data_in_db
+
+
 #  Setup middleware
 dp.middleware.setup(UserMiddleware())
 
 #  Binding filters
 dp.filters_factory.bind(
     BanUserFilter,
-    event_handlers=[dp.message_handlers, dp.callback_query_handlers],
+    exclude_event_handlers=[dp.channel_post_handlers, dp.edited_channel_post_handlers],
 )
 dp.filters_factory.bind(
     IsEvenIdFilter,
     event_handlers=[dp.message_handlers, dp.callback_query_handlers],
 )
+dp.filters_factory.bind(DatabaseIsNotEmptyFilter)
 
 
 @dp.message_handler(banned=True)
@@ -89,12 +107,17 @@ async def handler_start1(message: types.Message):
     await message.answer("Congratulations, you are banned!")
 
 
-@dp.message_handler(commands="start", is_even=True)
-async def handler_start2(message: types.Message, is_even: bool):
+@dp.message_handler(data_in_db=6)
+async def handler_start2(message: types.Message):
+    await message.answer("There are too many records in the database!")
+
+
+@dp.message_handler(is_even=True)
+async def handler_start3(message: types.Message, is_even: bool):
     if is_even:
-        await message.answer("Congratulations, you id is even!")
+        await message.answer("Congratulations, your id is even!")
     else:
-        await message.answer("Congratulations, your id is not even")
+        await message.answer("Congratulations, your id is not even :(")
 
 
 if __name__ == "__main__":