Filters

Filters What, Why and How !

What is a filter?

A filter is used to as the name implies :) filter incoming updates. for example, lets say that we have a MessageBlock that we want it to only process Message with the text “/start”

we will pass the tgram filters.command() to the block just like this:

from tgram import filters

MessageBlock(
    ...,
    filter=(
        filters.command("start", prefixes="/")
    )
)

Why Do We Use Filters?

We use filters not only to filter incoming updates But also to seperate our app logic Instead of 1 big MessageFlow that has 1 big MessageBlock that process all messages We can have multiple Flows and multiple MessageBlocks to handle different data

For example we can have 1 MessageFlow processing our bot basic commands Like /start, /about, /support, /language etc… And this flow includes 4 MessageBlocks to process each command

How Do We Use Filters?

alot of basic filters like

• command.

• chat.

• etc…

can be found in tgram documentation.

but those filters can be limiting sometimes…, what if we want a custom filter to fill our needs?

How To Create A Custom Filter

for this example, lets make a vip-users list filter that only passes if the ComingUpdate is from a vip-user

lets start!

from tgram import TgBot, filters
from tgram.types import Update

def vip_only(vip_users_list: list[str]):

    def inner_filter(
        bot: TgBot,
        update: Update
    ) -> bool:
        # here is our actual filter, a filter takes in
        # bot: your bot instance
        # update: the incoming update, it can be one of Message, CallbackQuery, etc...
        # and returns a boolean, true if this update is allowes, False if not

        # get username from the update
        username = "@" + update.from_user.username

        # check if the user is VIP or not
        if username in vip_users_list:
            return True
        else:
            return False

    # now after making out filter above, lets return it as a Filter type
    return filters.Filter(inner_filter)

Congrats! now you made your own custom filter, you can test it thorugh this example