Filtering records based on empty value of column in SparkSql

[Prashant Bhardwaj]

Hi

I have two columns in my json which can have null, empty and non-empty
string as value.
I know how to filter records which have non-null value using following:

val req_logs = sqlContext.read.json(filePath)

val req_logs_with_dpid = req_log.filter("req_info.dpid is not null or
req_info.dpid_sha1 is not null")

But how to filter if value of column is empty string?
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Regards
Prashant