Spark Streaming：在流转换期间使用外部数据

I have a situation where I have to filter data-points in a stream based on some condition involving a reference to external data. I have loaded up the external data in a Dataframe (so that I get to query on it using SQL interface). But when I tried to query on Dataframe I see that we cannot access it inside the transform (filter) function. (sample code below)I have a situation where I have to filter data-