Searching for NULL Values

Regardless of your feelings about NULL, they do exist in databases and Marten allows you to search for documents that have (or don't have) null values:

public void query_by_nullable_type_nulls(IDocumentSession session)
{
    // You can use Nullable<T>.HasValue in Linq queries
    session.Query<Target>().Where(x => !x.NullableNumber.HasValue).ToArray();
    session.Query<Target>().Where(x => x.NullableNumber.HasValue).ToArray();

    // You can always search by field is NULL
    session.Query<Target>().Where(x => x.Inner == null);
}

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