/// <summary>
        /// 保存头像
        /// </summary>
        /// <param name="avatar">头像详细信息</param>
        /// <returns>true or false</returns>
        public bool Save(AvatarModel avatar)
        {
            using (var dbContext = new MissionskyOAEntities())
            {
                var entity = dbContext.Avatars.Include(it => it.User).FirstOrDefault(item => (item.UserId == avatar.UserId));
                if (entity != null)
                {
                    entity.FileName    = avatar.FileName;
                    entity.Content     = avatar.Content;
                    entity.CreatedTime = DateTime.Now;
                }
                else
                {
                    dbContext.Avatars.Add(avatar.ToEntity());
                }

                dbContext.SaveChanges();
            }

            return(true);
        }