messengerapi/code/MessengerApi.Db/Repositories/Repository.cs

using MessengerApi.Db.Contracts.Entities;
using MessengerApi.Db.Contracts.Repositories;
using Microsoft.EntityFrameworkCore;

namespace MessengerApi.Db.Repositories
{
    public abstract class Repository<T> : IRepository<T> where T : class, IEntity<T>
    {
        protected readonly DbSet<T> db;

        public Repository(DbSet<T> db)
        {
            this.db = db;
        }

        public void Add(T entity)
        {
            this.db.Add(entity);
        }

        public T GetById(Guid id)
        {
            return this.db.Single(x => x.Id == id);
        }
    }
}