telegram-bot/modules/UrlLimitations/UserJoinHandler.cs

using System;
using System.Threading.Tasks;
using BotFramework;
using BotFramework.Attributes;
using BotFramework.Enums;
using BotFramework.Setup;
using Kruzya.TelegramBot.Core.Cache;
using Kruzya.TelegramBot.Core.Data;
using Kruzya.TelegramBot.Core.Extensions;
using Telegram.Bot.Types.Enums;

namespace Kruzya.TelegramBot.UrlLimitations
{
    public class UserJoinHandler : BotEventHandler
    {
        protected readonly CoreContext dbCtx;
        
        public UserJoinHandler(CoreContext coreContext)
        {
            dbCtx = coreContext;
        }

        [InChat(InChat.Public)]
        [Message(MessageFlag.HasNewChatMembers)]
        public async Task OnChatMembersAdded()
        {
            foreach (var member in RawUpdate.Message.NewChatMembers)
                await dbCtx.UserValues.SetOptionValue<UInt16>(Chat.Id, member.Id, "urlLimitations.messagesAfterJoin",
                    0);
        }
    }
}