Aditya created SAMZA-1740:
-----------------------------
Summary: Samza-sql: Move SamzaSqlRelRecord class out of
SamzaSqlRelMessage (for UDFs).
Key: SAMZA-1740
URL: https://issues.apache.org/jira/browse/SAMZA-1740
Project: Samza
Issue Type: Bug
Reporter: Aditya
For app users to extract nested fields from avro records, they need to write
their own UDFs. For that, they will have to refer to avro records as Java types
that Samza SQL translates to and uses, and not as Avro GenericRecord. In
Samza-sql, we convert GenericRecord to SamzaSqlRelRecord. Currently,
SamzaSqlRelRecord is an inner class of SamzaSqlRelMessage. Considering that we
are making these Java types be directly usable by app writers in UDFs, we will
have to make SamzaSqlRelRecord an independent class. We will also have to move
this class to Samza api module.
An example of how SamzaSqlRelRecord could be used in UDF to extract pageKey
from PageViewEvent is below:
/**
*UDF that fetches the brooklin envelope metadata value, given a fieldName.
*/
public class GetPageKeyUdf implements ScalarUdf<String> {
@Override
public void init(Config udfConfig) {
}
@Override
public String execute(Object... args) {
SamzaSqlRelRecord record = (SamzaSqlRelRecord) args[0];
Optional<Object> fieldValue = Optional.empty();
if (record != null)
{ fieldValue = record.getField("pageKey"); }
if (fieldValue.isPresent())
{ return fieldValue.get().toString(); }
return null;
}
}
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