How do I edit a row that already exists - asp.net-mvc

Question

I'm adding a row to Videos and then I want to use that same ID as the video's physical filename. so I need to add the row without the filename, and then use the ID I get, then update that row with the filename. I'm just now sure how to do that.
public ActionResult UpVideo(Report Report, string VideoName, HttpPostedFileBase file)
{
Video v = new Video();
v.Name = VideoName;
v.Report = Report;
db.Videos.Add(v);
var filename = v.ID + "." + Path.GetExtension(file.FileName);
var path = Path.Combine(Server.MapPath("~/App_Data/video_uploads"), filename);
file.SaveAs(path);
v.FileName = filename;
//** update Row here with filename
db.SaveChanges();
//** redirect back to Report Details (need to figure out how do do this too)
return RedirectToAction(Report);
}

Answer 1

Assuming that you have an auto incrementing primary key for ID in your database, you need to call save changes before referencing the ID property. You have to save the entity to the database so that the ID can be assigned.
public ActionResult UpVideo(Report Report, string VideoName, HttpPostedFileBase file)
{
Video v = new Video();
v.Name = VideoName;
v.Report = Report;
db.Videos.Add(v);
db.SaveChanges();
var filename = v.ID + "." + Path.GetExtension(file.FileName);
var path = Path.Combine(Server.MapPath("~/App_Data/video_uploads"), filename);
file.SaveAs(path);
v.FileName = filename;
db.SaveChanges();
//** redirect back to Report Details (need to figure out how do do this too)
return RedirectToAction(Report);
}
Since 'filename' is only a combination of the Id and the file extension, why not just save the file extension and do the concatenation when you need to reference the video. This would reduce your calls to the database back down to one and save a little on DB storage
public ActionResult UpVideo(Report Report, string VideoName, HttpPostedFileBase file)
{
Video v = new Video();
v.Name = VideoName;
v.FileName = Path.GetExtension(file.FileName);
v.Report = Report;
db.Videos.Add(v);
db.SaveChanges();
var filename = v.ID + "." + v.FileName;
var path = Path.Combine(Server.MapPath("~/App_Data/video_uploads"), filename);
file.SaveAs(path);
//** redirect back to Report Details (need to figure out how do do this too)
return RedirectToAction(Report);
}