I've start wondering what's the best practice when handling objects in web development.

Oversimplified the process when there is a page request often looks like:

1. Page request.
2. Fetch object data from database.
3. Create object.
4. Return object to page.

And on POST or save:

1. Get data from page.
2. (Create object) could be done in 1.
3. Save object data to database.

I've written a sample code below:

public class Product
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Category { get; set; }

    public bool SaveNew()
    {
        SaveToDatabase(this.Id, this.Name, this.Category);
    }
    public void SetElementsById()
    {
         var datarows = GetProductDataByIdFromDB(this.Id);
         Name = datarows[1].ToString();
         Category = datarows[2].ToString();
    }
}

public class ProductHandler
{
    public bool SaveNew(Product product)
    {
        SaveToDatabase(product.Id, product.Name, product.Category);
    }
    public void GetProductById(int id)
    {
        Product product = new Product();
        product.Id = id;
        
        var datarows = GetProductDataByIdFromDB(id);
        product.Name = datarows[1].ToString();
        product.Category = datarows[2].ToString();
    }
} 

What is the best practice, to handle the object data within the object or in a handler type of class?