telegram-bot/Core/DbResolverParameter.cs

using System;
using BotFramework;
using Microsoft.EntityFrameworkCore;

namespace Kruzya.TelegramBot.Core
{
    /// <summary>
    /// Resolves the GUIDs from database to entities.
    /// </summary>
    /// <typeparam name="TResolvedEntity">Entity type</typeparam>
    /// <typeparam name="TAppContext">Database context where entity should be finded</typeparam>
    public class DbResolverParameter<TResolvedEntity, TAppContext> : IParameterParser<TResolvedEntity>
        where TAppContext : DbContext
        where TResolvedEntity : class
    {
        private TAppContext _dbContext;

        public DbResolverParameter(TAppContext dbContext)
        {
            _dbContext = dbContext;
        }
        
        public TResolvedEntity DefaultInstance()
        {
            return default(TResolvedEntity);
        }

        public bool TryGetValue(string text, out TResolvedEntity result)
        {
            result = null;
            Guid id;
            if (Guid.TryParse(text, out id))
            {
                result = _dbContext.Find<TResolvedEntity>(id);
                return (result != null);
            }

            return false;
        }
    }
}