[Mondrian] Problem moving UDF returning a list from 2.4 to 3.1.1

[Julian Hyde]

I'll look into it over the weekend. Can you please log a bug.
 
Julian


  _____  

From: mondrian-bounces at pentaho.org [mailto:mondrian-bounces at pentaho.org] On
Behalf Of Eric McDermid
Sent: Friday, July 31, 2009 10:36 AM
To: Mondrian developer mailing list
Subject: [Mondrian] Problem moving UDF returning a list from 2.4 to 3.1.1


I'm having some trouble with a UDF returning a List that worked under 2.4,
but fails with a parse error under 3.1.1.  I'm not sure whether the problem
is a flaw in the UDF or in how the newer version of Mondrian is attempting
to use it.  

Here's the function, which simply reverses the order of a set:

  public class ReverseFunction implements UserDefinedFunction {
public Object execute(Evaluator eval, Argument[] args) {
List memberList = (List) args[0].evaluate(eval);
Collections.reverse(memberList);
return memberList;
}
public String getDescription() {
return "Reverses the order of a set";
}
public String getName() {
return "Reverse";
}
public Type[] getParameterTypes() {
return new Type[] {new SetType(MemberType.Unknown)};
}
public String[] getReservedWords() {
return null;
}
public Type getReturnType(Type[] arg0) {
return arg0[0];
}
public Syntax getSyntax() {
return Syntax.Function;
}
  }

The stack trace for the underlying cause of the error is here:

Caused by: mondrian.olap.MondrianException: Mondrian Error:Internal error:
Cannot convert calc to list: mondrian.olap.fun.UdfResolver$CalcImpl at 315d04
at mondrian.resource.MondrianResource$_Def0.ex(MondrianResource.java:803)
at mondrian.olap.Util.newInternal(Util.java:1465)
at
mondrian.calc.impl.AbstractExpCompiler.compileList(AbstractExpCompiler.java:
286)
at
mondrian.calc.impl.BetterExpCompiler.compileList(BetterExpCompiler.java:77)
at
mondrian.calc.impl.AbstractExpCompiler.compileList(AbstractExpCompiler.java:
260)
at
mondrian.olap.fun.SetFunDef$MemberSetListCalc.createCalc(SetFunDef.java:147)
at
mondrian.olap.fun.SetFunDef$MemberSetListCalc.compileSelf(SetFunDef.java:134
)
at mondrian.olap.fun.SetFunDef$MemberSetListCalc.<init>(SetFunDef.java:120)
at mondrian.olap.fun.SetFunDef.compileCall(SetFunDef.java:89)
at mondrian.mdx.ResolvedFunCall.accept(ResolvedFunCall.java:152)
at
mondrian.calc.impl.AbstractExpCompiler.compile(AbstractExpCompiler.java:79)
at
mondrian.calc.impl.AbstractExpCompiler.compileAs(AbstractExpCompiler.java:12
4)
at
mondrian.calc.impl.AbstractExpCompiler.compileIter(AbstractExpCompiler.java:
311)
at mondrian.olap.QueryAxis.compile(QueryAxis.java:122)
at mondrian.olap.Query.compile(Query.java:519)
at mondrian.olap.Query.resolve(Query.java:456)
at mondrian.olap.Query.<init>(Query.java:231)
at mondrian.olap.Query.<init>(Query.java:187)
at mondrian.olap.Parser.makeQuery(Parser.java:870)
at mondrian.olap.CUP$Parser$actions.CUP$Parser$do_action(Parser.java:1764)
at mondrian.olap.Parser.do_action(Parser.java:699)
at java_cup.runtime.lr_parser.parse(lr_parser.java:569)
at mondrian.olap.Parser.parseInternal(Parser.java:772)

The immediate problem is in AbstractExpCompiler.compileList().  It compiles
the expression "Reverse([Requested Dates])", gets a
mondrian.olap.fun.UdfResolver$CalcImpl instance as a result, then complains
because said calc is neither null, a ListCalc, or an IterCalc.

UDF documentation seems a little thin, and I've been unable to find an
example of a UDF returning a list in either mondrian/udf or in UdfTest to
use as a reference point.  Searching the archive, I do see that Pappyn Bart
asked a somewhat similar question back in 2007, but I didn't see a clear
resolution.

Can anyone help me sort this problem out, or failing that at least point me
to an example of a UDF that does successfully return a list that I can
compare against?

 -- Eric



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