What causes "The function call rpad requires 3 arguments." in pentaho/pentaho-kettle?

Call rpad with exactly three arguments: rpad(value, size, filler).

pentaho/pentaho-kettle · error · RuntimeException

The function call rpad requires 3 arguments.

Error message

The function call rpad requires 3 arguments.

What it means

rpad() right-pads a string to a target size with a filler string. Like lpad, it requires exactly three arguments; any missing argument or inner exception is converted to this RuntimeException and the function returns null.

Solutions

Call rpad with exactly three arguments: rpad(value, size, filler).
Ensure size is numeric and filler is a string.
Guard against null values before calling rpad.
Replace dynamic argument construction with a fixed three-argument call.

Example fix

// before
var padded = rpad(name, 10);
// after
var padded = rpad(name, 10, " ");

Defensive patterns

Strategy: validation

Validate before calling

if (value != null && typeof size === "number" && size > 0) { var padded = rpad(value, size, filler); }

Type guard

function canRpad(v, size, filler) { return v != null && typeof size === "number" && size > 0 && filler != null && String(filler).length > 0; }

Try / catch

try {
  var padded = rpad(value, size, filler);
  if (padded === null) { /* argument-count failure path */ }
} catch (e) {
  Logger.LogBasic("rpad failed: " + e.message);
  padded = value;
}

Prevention

Pass exactly three arguments to rpad().
Validate size numerically before the call.
Use a non-empty string filler.
Check for null return values, which signal the failure path.

When it happens

Trigger: Calling rpad(value) or rpad(value, size) in a Script step, or a three-argument call whose processing throws (bad size type, null value), which lands in the same catch.

Common situations: Porting two-argument RPAD usage from other languages; building the argument list dynamically and dropping the filler argument.

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

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/253290609d3605db. Report an issue: GitHub.

Appendix: source

Thrown at engine/src/main/java/org/pentaho/di/trans/steps/script/ScriptAddedFunctions.java:822

    Object FunctionContext ) {
    try {
      if ( ArgList.length == 3 ) {
        if ( isNull( ArgList, new int[] { 0, 1, 2 } ) ) {
          return null;
        } else if ( isUndefined( ArgList, new int[] { 0, 1, 2 } ) ) {
          return (String) undefinedValue;
        }
        String valueToPad = (String) ArgList[0];
        String filler = (String) ArgList[1];
        int size = (Integer) ArgList[2];

        while ( valueToPad.length() < size ) {
          valueToPad = valueToPad + filler;
        }
        return valueToPad;
      }
    } catch ( Exception e ) {
      throw new RuntimeException( "The function call rpad requires 3 arguments." );
    }
    return null;
  }

  public static Object year( ScriptEngine actualContext, Bindings actualObject, Object[] ArgList,
    Object FunctionContext ) {
    try {
      if ( ArgList.length == 1 ) {
        if ( isNull( ArgList[0] ) ) {
          return new Double( Double.NaN );
        } else if ( isUndefined( ArgList[0] ) ) {
          return undefinedValue;
        }
        java.util.Date dArg1 = (java.util.Date) ArgList[0];
        Calendar cal = Calendar.getInstance();
        cal.setTime( dArg1 );
        return new Double( cal.get( Calendar.YEAR ) );
      } else {

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