Passing a bag as an input for UDF in PIG - hadoop

Question

I'm trying to pass a databag(final) as an input.
dump final;
gives:-
(4,john,john,David,Banking ,4,M,20-01-1994,78.65,345000,Arkansasdest1,Destination)
(4,john,john,David,Banking ,4,M,20-01-1994,78.65,345000,Arkanssdest2,Destination)
(4,johns,johns,David,Banking ,4,M,20-01-1994,78.65,345000,ArkansasSrc1,source)
(4,johns,johns,David,Banking ,4,M,20-01-1994,78.65,345000,ArkansaSrc2,source)
I'm about to write an UDF for processing the above databag and finding mismatch between Source and Destination, in order to do that i have to check whether my UDF accepts databag or not. so i wrote one sample UDF below:
package PigUDFpck;
import java.io.IOException;
import java.util.Iterator;
import org.apache.pig.EvalFunc;
import org.apache.pig.data.BagFactory;
import org.apache.pig.data.DataBag;
import org.apache.pig.data.Tuple;
import org.apache.pig.data.TupleFactory;
public class databag extends EvalFunc<DataBag> {
TupleFactory mTupleFactory = TupleFactory.getInstance();
BagFactory mBagFactory = BagFactory.getInstance();
public DataBag exec(Tuple input) throws IOException { // different return type
DataBag result = mBagFactory.newDefaultBag(); // change here
DataBag values = (DataBag)input.get(0);
for (Iterator<Tuple> iterator = values.iterator(); iterator.hasNext();) {
Tuple tuple = iterator.next();
//logic
Tuple t = mTupleFactory.getInstance().newTuple();
t.append(tuple);
result.add(t);
}
return result; // change here
}
}
After that I registered the path using
REGISTER /usr/local/pig/UDF/UDFBAG.jar;
DEFINE Databag Databag(); // not sure how to define it
2017-02-16 19:07:05,875 [main] WARN org.apache.pig.newplan.BaseOperatorPlan - Encountered Warning IMPLICIT_CAST_TO_INT 2 time(s). //got this warning after defining.
final1 = FOREACH final GENERATE(Databag(final));
ERROR 1200: Pig script failed to parse:
Invalid scalar projection: final : A column needs to be projected from a relation for it to be used as a scalar
Please help me on Defining the UDF and how to pass a DataBag to UDF
Thanks

Answer 1

Try
final1 = FOREACH final GENERATE(Databag(*));
Though as far as I see, your final contains tuples, not bags of tuples, so you'll probably need to first group it by some key. in that case it will be smth like
final1 = FOREACH (group final [by key or all]) GENERATE(Databag(final));