Question

I have binding into the class, but not in another. I can`t call Product from Item: Object reference not set to an instance of an object.

Whats wrong?

How optimize this code?

foreach (var xd in excelData)
{
    Product p = new Product { 
        Name = xd.ProductName,
    };

    ctx.Products.Add(p);
    ctx.SaveChanges();

    Item t = new Item { 
        Product=p,
    };

    t.ProductId = t.Product.ProductId;
    ctx.Items.Add(t);
    ctx.SaveChanges();

    t.Product = ctx.Products.Where(c => c.ProductId == t.ProductId).FirstOrDefault();
    ctx.SaveChanges();
}

Answer 1

ObjectQuery.Include Method. Specifies the related objects to include in the query results.

ctx.Items.Include("Product").Where(c => c.SupplierId == id).ToList().ForEach(t =>
        {
            li.Add(new ShortPricesListItem()
            {
                Name = t.Product.Name,
            });
        });