How to create a new instance of DbContext with a specific connection string as constructor parameter?

Question

I have such constructor of ApplicationDbContext class (I think quite standard one)

public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options): base(options)
{
}

How I can create a new class instance with a specified connection string?

ApplicationDbContext   applicationDbContext = new ApplicationDbContext (??);

Answer 1

You can save your email data like below:

/// <summary>
        /// SentBulkEmail to recipient
        /// </summary>
        /// <param name="emailModel"></param>
        /// <param name="sentBy"></param>
        public async Task<CustomResponseModel> SentBulkEmail(SendEmailModel emailModel, int sentBy = 0)
        {
            CustomResponseModel response = new CustomResponseModel();
            try
            {
                List<EmailSentHistoryModel> lstEmailSentHistory = new List<EmailSentHistoryModel>();
                Parallel.ForEach(emailModel.Recipient, (item) =>
                {
                    EmailSentHistoryModel historyModel = new EmailSentHistoryModel();
                    historyModel.EmailTemplateId = emailModel.EmailTemplateId;
                    historyModel.IsSent = Utilities.SendEmail(item, emailModel.Description, emailModel.Subject);
                    historyModel.Recipient = item;
                    historyModel.Sentdate = DateTime.UtcNow;
                    historyModel.Sentby = sentBy;
                    lstEmailSentHistory.Add(historyModel);
                });
                response = await _emailTemplateRepository.SaveEmailSentHistory(lstEmailSentHistory);
                response.Message = "Email sent successfully!!";
            }
            catch (Exception ex)
            {
                response.IsSuccess = false;
                response.Message = Constant.ServerError;
                _logger.LogError("{0}: SentBulkEmail() : {1}", Constant.ServiceError, ex.Message);
            }
            return response;
        }

Below is Email sent method:

public static bool SendEmail(string emailAddress, string body, string subject)
        {
            var _logger = NLogBuilder.ConfigureNLog("nlog.config").GetCurrentClassLogger();
            try
            {
                using (MailMessage mail = new MailMessage(ConfigItems.From, emailAddress))
                {
                    mail.Subject = subject;
                    mail.Body = body;
                    mail.IsBodyHtml = true;
                    SmtpClient smtp = new SmtpClient()
                    {
                        Host = ConfigItems.Host,
                        EnableSsl = true
                    };
                    NetworkCredential NetworkCred = new NetworkCredential(ConfigItems.From, ConfigItems.Password);
                    smtp.UseDefaultCredentials = false;
                    smtp.Credentials = NetworkCred;
                    smtp.EnableSsl = true;
                    smtp.Port = ConfigItems.Port;
                    smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
                    smtp.Send(mail);
                }
                return true;
            }
            catch (Exception ex)
            {
                _logger.Error(ex.Message.ToString());
                return false;
            }
        }

You can see in SentBulkEmail I used that method to get whether email and sent or not and also save the data from their as well.