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c#sql-server-2008asp.net-mvc-3-areas

How to know current new object's ID in advance, before saving?

In my ASP.NET MVC3 application (C#, SQL Server) Product has ImagePath as string type. When I save the image, I want to give product's ID value to ImagePath. When I create new product, I don't know what will be the current product's ID before db.SaveChanges();

 public ActionResult Create( Product product )
   { 
       .....
       .....//How to know ID of this product in advance?
       .....
       db.Products.AddObject( product );
       db.SaveChanges();
   }

I can find last item of products and increase it: 

currentID = lastID + 1;

But, maybe the last ID was deleted. Result will not correct..

Solution

  • I'd suggest the following approach:

    //don't save the image yet, or save it in a temporary location
db.Products.AddObject( product );
db.SaveChanges();
product.ImagePath = //path including product.Id
//save or move image to product.ImagePath
db.SaveChanges();