Cannot save multiple files to database with Foreign Key - sql-server

Question

In my MVC application I have two tables called Ticket and Attachment and I want to save attachments for per ticket. The problem is that: I need to save multiple attachments with the TicketID when creating a new ticket. So, I think I should create a new ticket in the Ticket table and then get its ID and save all the attachments with this TicketID to the Attachment table in a loop. I have look at many web sites and stackoverflow, but there is not such a kind of problem or solution on that pages. Any idea?
Note: I use Entity Framework Code First, but I can also use Stored Procedure or SQL command for this operation.
Here are these two models:
public class Ticket
{
[Key]
public int ID { get; set; }
public string Description { get; set; }
//... removed for clarifty
}
public class Attachment
{
[Key]
public int ID { get; set; }
//Foreign key for Ticket
public int TicketID { get; set; }
public byte[] FileData { get; set; }
public string FileMimeType { get; set; }
}
And the controller method:
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create([Bind(Exclude = null)] TicketViewModel viewModel
/* contains both model: Ticket and Attachment */, IEnumerable<HttpPostedFileBase> files)
{
if (ModelState.IsValid)
{
//??? First I need to save Ticket
repository.SaveTicket(viewModel.Ticket);
foreach(var f in files)
{
viewModel.Attachment.FileMimeType = f.ContentType;
viewModel.Attachment.FileData = new byte[f.ContentLength];
f.InputStream.Read(viewModel.Attachment.FileData , 0, f.ContentLength);
//??? Then save all attachment. But no idea how to get TicketID
repository.SaveAttachment(viewModel.Attachment);
}
}
return View();
}

Answer 1

The ID property will be automatically filled by EF after a SaveChanges. Your code can then use it. I assume that the viewModel.Ticket object is the actual object saved to the database. If not, please also post the SaveTicket method.
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create([Bind(Exclude = null)] TicketViewModel viewModel
/* contains both model: Ticket and Attachment */, IEnumerable<HttpPostedFileBase> files)
{
if (ModelState.IsValid)
{
// assumes viewModel.Ticket is the actual entity saved, and SaveChanges is called.
repository.SaveTicket(viewModel.Ticket);
foreach(var f in files)
{
viewModel.Attachment.FileMimeType = f.ContentType;
viewModel.Attachment.FileData = new byte[f.ContentLength];
f.InputStream.Read(viewModel.Attachment.FileData , 0, f.ContentLength);
// fill ticket id
viewModel.Attachment.TicketID = viewModel.Ticket.ID;
repository.SaveAttachment(viewModel.Attachment);
}
}
return View();
}
If you want to do everything in one transaction, you can add the childs immediatly, and SaveChanges will save all objects:
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create([Bind(Exclude = null)] TicketViewModel viewModel
/* contains both model: Ticket and Attachment */, IEnumerable<HttpPostedFileBase> files)
{
if (ModelState.IsValid)
{
var ticket = viewModel.Ticket;
foreach(var f in files)
{
var attachment = new Attachment();
attachment.FileMimeType = f.ContentType;
attachment.FileData = new byte[f.ContentLength];
f.InputStream.Read(attachment.FileData , 0, f.ContentLength);
ticket.Attachments.Add(attachment);
}
// this will save the ticket and attachments
repository.SaveTicket(ticket);
}
return View();
}
Your Ticket class will have to look like this:
public class Ticket
{
[Key]
public int ID { get; set; }
public string Description { get; set; }
// EF will now to use the foreign key to the attachment table
public virtual ICollection<Attachment> Attachments { get; set; }
}