Strange issue in Blazor client when the model changes

[carlblanchard]

Hi All. I thought I'd raise this as a discussion rather than a bug as it may be something I've created, or perhaps a lack of understanding.,.

In my Blazor client application, I have a select list of countries. I populate from my model (ExistingRecords) with the countries to display in the select.
My Model looks like this

public class GenericModel<T>
    {
        public List<T> ExistingRecords { get; set; }

        public T NewOrEditItem { get; set; }

        public GenericModel()
        {
            this.ExistingRecords = new List<T>();
            this.NewOrEditItem = (T)Activator.CreateInstance(typeof(T));

        }
    }

When I select one of the items from the select list to edit. I set the NewOrEditItem to the value selected. This, in turn, causes the select list to rerender. I know it rerenders because I have debug.writes and the first item is always selected rather than the one chosen.
If I remove the setting of NewOrEditItem then the value I selected remains in the dropdown list.

My guess that due to the model being updated, the StateHasChange event is fired and everything gets updated. I've overcome my problem by directly setting the selected value to the item in the NewOrEditItem. My concern is, this is a simple model, overtime as my models become more complicated this will become more problematic.
Should I be breaking my models down i.e. LoadModel, NewOrEditModel etc.
Or is there a way to cause partial updates only when parts of the model change?

Many thanks for reading, look forward to your comments.