EF6 对于实体字段类型转换扩展

public class UtcDbDataReader : DbDataReader
{
    private readonly DbDataReader source;

    public UtcDbDataReader(DbDataReader source)
    {
        this.source = source;
    }

    public override DateTime GetDateTime(int ordinal)
    {
        return DateTime.SpecifyKind(source.GetDateTime(ordinal), DateTimeKind.Utc);
    }        

    // you need to fill all overrides. Just call the same method on source in all cases

    public new void Dispose()
    {
        source.Dispose();
    }

    public new IDataReader GetData(int ordinal)
    {
        return source.GetData(ordinal);
    }
}

public class UtcInterceptor : DbCommandInterceptor
{
    public override void ReaderExecuted(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
    {
        base.ReaderExecuted(command, interceptionContext);

        if (interceptionContext?.Result != null && !(interceptionContext.Result is UtcDbDataReader))
        {
            interceptionContext.Result = new UtcDbDataReader(interceptionContext.Result);
        }
    }
}

internal class MyDbConfiguration : DbConfiguration
{
    protected internal MyDbConfiguration ()
    {           
        AddInterceptor(new UtcInterceptor());
    }
}

[DbConfigurationType(typeof(MyDbConfiguration ))]
internal class MyDbContext : DbContext
{
    // ...
}