插入后，重定向到编辑页面。 无法获取ID

Question

I have FormView in Category_New.aspx from where new item is inserted. It is inserted in following method.

 public void myForm_InsertItem()
    {            
        var item = new A.Models.Category();
        CategoryContext db = new CategoryContext();            
        TryUpdateModel(item);
        if (ModelState.IsValid)
        {
            // Save changes here
            db.Category.Add(item);
            db.SaveChanges();
            //item.CategoryID is present from this point
        }
    }

I would like to redirect a user to the page that is for editing that Item. That page is Category_Edit.aspx.

How to get ID of inserted item in method myForm_ItemInserted so that the following code would work?

protected void myForm_ItemInserted(object sender, FormViewInsertedEventArgs e)
{
     Response.RedirectToRoute(GetRouteUrl("CategoryEdit", new {CategoryID = /* how to get ID of inserted item??? */}));            
}

How to know the ID of inserted item?

Answer 1

What you probably can do is to have a global int type variable to hold the value of new category Id, then you can pass it in in your redirect method.

private int newCategoryId;
public void myForm_InsertItem()
    {            
        var item = new A.Models.Category();
        CategoryContext db = new CategoryContext();            
        TryUpdateModel(item);
        if (ModelState.IsValid)
        {
            // Save changes here
            db.Category.Add(item);
            db.SaveChanges();
            //item.CategoryID is present from this point
            newCategoryId = item.CategoryId; // presumably it's called categoryId
        }
    }

protected void myForm_ItemInserted(object sender, FormViewInsertedEventArgs e)
{
     Response.RedirectToRoute(GetRouteUrl("CategoryEdit", new {CategoryID = newCategoryId}));            
}

The key here is that when inserting, the generated ID is saved into the instance of the object being saved.

Answer 2

If you are using entity framework, It will persist save object auto generated id at the time data inserted to the database.

Normally entity framework execute SELECT SCOPE_IDENTITY() to get when auto-generated Ids.

Therefore you should be able to get inserted id as following.

int Id= item.ID;