Chat members plugin for grammY

This plugin watches for chat_member updates and stores a list of users, their statuses and permissions for each chat in which they and the bot are a member.

Usage

Storing chat members

You can use a valid grammY storage adapter or an instance of any class that implements the StorageAdapter interface.

import { Bot, Context, MemorySessionStorage } from "https://deno.land/x/grammy/mod.ts";
import type { ChatMember } from "https://deno.land/x/grammy/types.ts";
import { chatMembers, ChatMembersFlavor } from "https://deno.land/x/grammy_chat_members/mod.ts";

type MyContext = Context & ChatMembersFlavor;

const adapter = new MemorySessionStorage<ChatMember>();

const bot = new Bot<MyContext>("<your bot token>");

bot.use(chatMembers(adapter));

bot.start({
  allowed_updates: ["chat_member", "message"],
  onStart: ({ username }) => console.log(`Listening as ${username}`),
});

Reading chat member info

This plugin also adds a new ctx.chatMembers.getChatMember function that will check the storage for information about a chat member before querying telegram for it. If the chat member exists in the storage, it will be returned. Otherwise, ctx.api.getChatMember will be called and the result will be saved to the storage, making subsequent calls faster and removing the need to call telegram again for that user and chat in the future.

Here’s an example:

bot.on("message", async (ctx) => {
  const chatMember = await ctx.chatMembers.getChatMember();

  return ctx.reply(`Hello, ${chatMember.user.first_name}! I see you are a ${chatMember.status} of this chat!`);
});

The second parameter, which is the chat id, is optional; if you don’t provide it, ctx.chat.id will be used instead. Please notice that, if you don’t provide a chat id and there’s no chat property inside the context (for example: on inline query updates), this will throw an error.

Aggressive storage

The enableAggressiveStorage config option will install middleware to cache chat members without depending on the chat_member event. For every update, the middleware checks if ctx.chat and ctx.from exist. If they both do, it then proceeds to call ctx.chatMembers.getChatMember to add the chat member information to the storage in case it doesn’t exist.

Please note that this means the storage will be called for every update, which may be a lot, depending on how many updates your bot receives. This also has the potential to impact the performance of your bot drastically. Only use this if you really know what you’re doing and are ok with the risks and consequences.