You are implementing a method that uses Entity Framework to update a Product entity. You add the following code:

public void UpdateProduct(Product product)
{
using (AdventureWorksEntities context = new AdventureWorksEntities())
{
context.Products.Attach(product);

context.SaveChanges();
}
}

When you execute the code, you find that the product is not updated. You need to modify the code to ensure that the product is updated.

What should you do?

In the Entity Framework, objects can be attached to, or detached from, an object context. Objects that are attached to an object context are tracked and managed by that object context. When a query is executed inside an object context in the Entity Framework, the returned objects are automatically attached to the object context. You can attach objects that have been returned from a remote method call or web service by calling the Attach method. Entities are attached in an Unchanged state. The ApplyOriginalValues method sets the OriginalValues of the ObjectStateEntry instance to match the values of the supplied object. When changes are applied to the original values of an object in an Unchanged state, the EntityState is changed to Modified. The ApplyOriginalValues method is used to set the original values of an object to the properties of an object outside the ObjectContext, such as detached objects that are received by a web service.