Entity framework 6 - Access the entity object during valueConverter - entity-framework-core

Question

I have a project with Entity Framework Core 6 for SQL. it's a large project with a lot of entities and properties (and yes, a lot...). All properties are defined not nullable (bool, int etc.) because the SQL database tables all are not-nullable columns also. All good.
But now this project must works with an Oracle database server, and here are tables with nullable columns which not match with the not nullable entities (Oracle EF cannot match nullabe column with a not-nullable directly).
Changing all columns with not nullable with default value isn't possible. And making the entities nullable give us a lot of (test) work because it hits the logical part of code.
So, my challenge is to find a solution that nullable table columns can set not-nullable entity properties with a value or default and without changing the entity set of code.
Using the ValueConverter is the first solution but it isn't possible because a null value will never be passed to a value converter.
So I try it with a shadow property. I have this:
entityTypeBuilder.Ignore(property.Name);
entityTypeBuilder.Property<int?>($"_Nullable_{property.Name}")
.HasConversion<NullableIntConverter >()
.HasColumnName(oracleColumn.ColumName);
Here I ignore the original property for EF, then I add a shadow property with converter for the nullable type (<int?>). This is the valueConverter:
internal class NullableIntConverter : ValueConverter<int, int?>
{
public NullableIntConverter()
: base(
_convertToEntityProviderExpression,
_convertToDbProviderExpression)
{
}
private static readonly Expression<Func<int?, int>> _convertToDbProviderExpression = x =>
x.GetValueOrDefault();
private static readonly Expression<Func<int, int?>> _convertToEntityProviderExpression = x => x;
}
This works, a nullable column set the shadow property but not the original property.
The solution will be setting the original property during ValueConverter. But because of static it isn't really possible. Or maybe someone have a solution here? If I have the entity object, I can use reflection for setting the original property.
I hope that someone have a tip for a solution?