Dapper type handler with nullable, now obsolete. Dapper handles this natively as of issue #136

example.cs

void Main()
{
    // SqlMapper.AddTypeHandler<T>(TypeHandler<T>) does not register the nullable version
    // Instead, use the SqlMapper.AddTypeHandler(Type, ITypeHandler) overload
    SqlMapper.AddTypeHandler(typeof(LocalDate), LocalDateHandler.Default);
    
    // Without this line a NullReferenceException is thrown
    SqlMapper.AddTypeHandler(typeof(LocalDate?), LocalDateHandler.Default);
    
    using (var db = new SqlConnection (@"Data Source=.;Initial Catalog=tempdb;Integrated Security=True")) {
        db.Open ();
        
        var param = new LocalDateResult {
            NotNullable = new LocalDate { Year = 2014, Month = 7, Day = 25 },
            NullableNotNull = new LocalDate { Year = 2014, Month = 7, Day = 26 },
            NullableIsNull = null,
        };
        var result = db.Query<LocalDateResult>("SELECT @NotNullable AS NotNullable, @NullableNotNull AS NullableNotNull, @NullableIsNull AS NullableIsNull", param).Single();
        result.Dump();
    }
}

public class LocalDateHandler : Dapper.SqlMapper.TypeHandler<LocalDate>
{
    private LocalDateHandler () { }

    // Make the field type ITypeHandler to ensure it cannot be used with SqlMapper.AddTypeHandler<T>(TypeHandler<T>)
    // by mistake.
    public static readonly SqlMapper.ITypeHandler Default = new LocalDateHandler();

    public override LocalDate Parse(object value)
    {
        var date = (DateTime)value;
        return new LocalDate { Year = date.Year, Month = date.Month, Day = date.Day };
    }

    public override void SetValue(IDbDataParameter parameter, LocalDate value)
    {
        parameter.DbType = DbType.DateTime;
        parameter.Value = new DateTime(value.Year, value.Month, value.Day);
    }
}

public struct LocalDate
{
    public int Year { get; set; }
    public int Month { get; set; }
    public int Day { get; set; }
}

public class LocalDateResult
{
    public LocalDate NotNullable { get; set;  }
    public LocalDate? NullableNotNull { get; set; }
    public LocalDate? NullableIsNull { get; set; }
}