I have an abstract AuditObject class with audit fields I can set automatically before saving changes on my entities.

public abstract class AuditObject
{
    public string CreatedBy { get; set; }
    public string UpdatedBy { get; set; }
}

In my DbContext before saving I set the audit fields:

 private void OnBeforeSaving()
 {
       var user = _someService.GetUserName();

       foreach (var entry in ChangeTracker.Entries()) 
       {
           if (entry.State == EntityState.Modified && entry.Entity is AuditObject auditObject) 
           {
               auditObject.UpdatedBy = user;
               entry.Property("CreatedBy").IsModified = false; 
           }
           else if (entry.State == EntityState.Added && entry.Entity is AuditObject auditObject)
           {
               auditObject.CreatedBy = user;
               auditObject.UpdatedBy = user;
           }
       }
 }

I inherit that on an entity I have with related entities as well:

public abstract class Order: AuditObject
{
    public long Id { get; set; }
    public List<OrderProducts> Products { get; set; }
}

public abstract class OrderProducts: AuditObject
{
    public long Id { get; set; }
    public string Name { get; set; }
}

Now when I receive the updated Order on my endpoint I set the Products list to the updated list.

[HttpPut("{id:long}")]
public async Task<Order> UpdateOrder(long id, Order order)
{
    var currentOrder = await _dbContext.Order
        .Include(x => x.Products)
        .FirstOrDefaultAsync(x => x.Id == order.Id);

    currentOrder.Products = order.Products;
    await _dbContext.SaveChangesAsync();

    return Ok(currentOrder);
}

When I debug through the change tracker entries Entity Framework believes there was a modified and deleted state and results in creating new records for the Products. So if I have an existing Order with 1 product with Id 1, the first change tracker entry it sees that OrderProduct 1 was modified, and sets the UpdatedBy and flags the CreatedBy as not modified. Then it has a change tracker entry of key 1 being deleted. The end result is I get an exception:

System.InvalidOperationException: The property
‘OrderProduct.CreatedBy’ cannot be
assigned a value generated by the database. Store-generated values can
only be assigned to properties configured to use store-generated
values.

On initial creation there is never an issue, the CreatedBy and UpdatedBy get set and a new OrderProduct record is created. It is only when I am updating the list of products with existing product Ids. Is there a way I can tell Entity Framework when assigning the list of products to not consider an update both a modify and delete?