pentaho/pentaho-kettle · error · RuntimeException

The function call num2str requires at least 1 argument.

Error message

The function call num2str requires at least 1 argument.

What it means

Thrown by num2str() in the PDI Script step when called with zero arguments; the function converts a numeric value to a string and requires at least the number itself (optional format and locale may follow).

Solutions

1. Pass the numeric field: num2str(myNumber).
2. Add a format argument if needed: num2str(myNumber, '####.00').
3. Check that the variable holding the number is not empty/undeclared in the script scope.

Example fix

// before
num2str()
// after
num2str(amount, '#,##0.00')

function safeNum2str(v, fmt) {
  if (v === undefined || v === null) return null;
  return fmt !== undefined ? num2str(v, fmt) : num2str(v);
}

function isNumber(v) { return typeof v === 'number' && !isNaN(v); }

try { return num2str(v); }
catch (e) { if (/requires at least 1 argument/.test(e.message)) return ''; throw e; }

When it happens

Trigger: num2str() invoked with an empty argument list, typically because the field reference evaluated to nothing or the argument was deleted during editing.

Common situations: A field variable name typo resolving to empty in the script; an edited call that dropped the number; template scripts pasted with placeholder arguments removed.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• The function call date2str requires 1, 2, 3, or 4 arguments.
• The function call lower requires 1 argument.
• The function call upper requires 1 argument.
• Please provide a valid date to the function call date2str.
• Row.EndOfFileReached

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/79100fc85c2323f4. Report an issue: GitHub.

Appendix: source

Thrown at engine/src/main/java/org/pentaho/di/trans/steps/script/ScriptAddedFunctions.java:1300

        }
        sRC = (String) ArgList[0];
        sRC = sRC.toLowerCase();
      } catch ( Exception e ) {
        throw new RuntimeException( "The function call lower is not valid : " + e.getMessage() );
      }
    } else {
      throw new RuntimeException( "The function call lower requires 1 argument." );
    }
    return sRC;
  }

  // Converts the given Numeric to a JScript String
  public static String num2str( ScriptEngine actualContext, Bindings actualObject, Object[] ArgList,
    Object FunctionContext ) {
    String sRC = "";
    switch ( ArgList.length ) {
      case 0:
        throw new RuntimeException( "The function call num2str requires at least 1 argument." );
      case 1:
        try {
          if ( isNull( ArgList[0] ) ) {
            return null;
          } else if ( isUndefined( ArgList[0] ) ) {
            return (String) undefinedValue;
          }
          double sArg1 = (Double) ArgList[0];
          if ( Double.isNaN( sArg1 ) ) {
            throw new RuntimeException( "The first Argument must be a Number." );
          }
          DecimalFormat formatter = new DecimalFormat();
          sRC = formatter.format( sArg1 );
        } catch ( IllegalArgumentException e ) {
          throw new RuntimeException( "Could not apply the given format on the number : " + e.getMessage() );
        }
        break;
      case 2:

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