Added example chat_member_updates.rs

crates/teloxide/examples/chat_member_updates.rs

@@ -0,0 +1,82 @@
+use teloxide::{
+    dispatching::Dispatcher,
+    prelude::*,
+    types::{ChatMemberUpdated, ParseMode, Update},
+    utils::html,
+};
+use teloxide_core::adaptors::DefaultParseMode;
+
+/// We use a type alias to be able to write just `bot: Bot` in handlers, instead
+/// of a lengthy `DefaultParseMode<Bot>`.
+///
+/// `DefaultParseMode` here is a [requester adaptor], that allows us to specify
+/// a default parse mode. The other option would be to use `.parse_mode(...)`
+/// after each API call manually (e.g.
+/// `bot.send_message(...).parse_mode(...).await?`).
+///
+/// [requester adaptor]: teloxide::requests::Requester#adaptors
+type Bot = DefaultParseMode<teloxide::Bot>;
+
+#[tokio::main]
+async fn main() -> ResponseResult<()> {
+    pretty_env_logger::init();
+
+    // We specify default parse mode to be `Html`, so that later we can use
+    // `html::user_mention`
+    let bot = teloxide::Bot::from_env().parse_mode(ParseMode::Html);
+
+    // Create a handler for our bot, that will process updates from Telegram
+    let handler = dptree::entry()
+        .inspect(|u: Update| {
+            eprintln!("{u:#?}"); // Print the update to the console with inspect
+        })
+        .branch(
+            Update::filter_chat_member()
+                .branch(
+                    dptree::filter(|m: ChatMemberUpdated| {
+                        m.old_chat_member.is_left() && m.new_chat_member.is_present()
+                    })
+                    .endpoint(new_chat_member),
+                )
+                .branch(
+                    dptree::filter(|m: ChatMemberUpdated| {
+                        m.old_chat_member.is_present() && m.new_chat_member.is_left()
+                    })
+                    .endpoint(left_chat_member),
+                ),
+        );
+
+    // Create a dispatcher for our bot
+    Dispatcher::builder(bot, handler).enable_ctrlc_handler().build().dispatch().await;
+
+    Ok(())
+}
+
+/// Welcome Endpoint
+async fn new_chat_member(bot: Bot, chat_member: ChatMemberUpdated) -> ResponseResult<()> {
+    let user = chat_member.old_chat_member.user.clone();
+
+    let telegram_group_name = chat_member.chat.title().unwrap_or("");
+
+    // We get a "@username" mention via `mention()` method if the user has a
+    // username, otherwise we create a textual mention with "Full Name" as the
+    // text linking to the user
+    let username =
+        user.mention().unwrap_or_else(|| html::user_mention(user.id, user.full_name().as_str()));
+
+    bot.send_message(chat_member.chat.id, format!("Welcome to {telegram_group_name} {username}!"))
+        .await?;
+
+    Ok(())
+}
+
+async fn left_chat_member(bot: Bot, chat_member: ChatMemberUpdated) -> ResponseResult<()> {
+    let user = chat_member.old_chat_member.user;
+
+    let username =
+        user.mention().unwrap_or_else(|| html::user_mention(user.id, user.full_name().as_str()));
+
+    bot.send_message(chat_member.chat.id, format!("Goodbye {username}!")).await?;
+
+    Ok(())
+}