pentaho/pentaho-kettle · error

The function call lpad requires 3 arguments.

Error message

The function call lpad requires 3 arguments.

What it means

The lpad() function in the JavaScript step pads a string on the left to a given size using a filler string. It requires exactly 3 arguments (value, size, filler); if the call throws for any reason — most commonly an argument count mismatch — it reports this error. Note the message is misleading: any exception in the body also produces it.

Solutions

1. Call lpad() with exactly 3 arguments: value, target size, filler string.
2. Null-check the value before padding.
3. Verify the size argument is a number and the filler is a non-empty string.
4. If a 2-argument call is desired, add the filler explicitly, e.g. lpad(field, 5, '0').

Example fix

// before
var padded = lpad(myField, 10);
// after
var padded = lpad(myField, 10, '0');

if (myField == null) throw 'lpad: value is null';
var padded = lpad(String(myField), 10, '0');

function canLpad(v, size, filler) { return v != null && typeof size === 'number' && typeof filler === 'string' && filler.length > 0; }

try { var padded = lpad(String(myField), 10, '0'); } catch (e) { var padded = String(myField); }

When it happens

Trigger: Calling lpad() in a modified JavaScript step with fewer than 3 arguments (e.g. lpad(field, 5)), or with arguments whose conversion fails (null value, non-numeric size).

Common situations: Scripts written against a different signature (some libraries' lpad takes only 2 args with a default filler), copy-pasted SQL LPAD with optional filler, or a null incoming field value.

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 rpad requires 3 arguments.
• The function call rtrim is not valid :
• Error in isEmpty function:
• Script.Log.CouldNotAddDefaultConstants
• ScriptValuesMod.Log.CouldNotAddDefaultConstants

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/b66522d07e7463a9. Report an issue: GitHub.

Appendix: source

Thrown at engine/src/main/java/org/pentaho/di/trans/steps/scriptvalues_mod/ScriptValuesAddedFunctions.java:828

    // (String valueToPad, String filler, int size) {
    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) Context.getUndefinedValue();
        }
        String valueToPad = Context.toString( ArgList[0] );
        String filler = Context.toString( ArgList[1] );
        int size = (int) Context.toNumber( ArgList[2] );

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

  public static String rpad( Context actualContext, Scriptable actualObject, Object[] ArgList,
    Function 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) Context.getUndefinedValue();
        }
        String valueToPad = Context.toString( ArgList[0] );
        String filler = Context.toString( ArgList[1] );
        int size = (int) Context.toNumber( ArgList[2] );

        while ( valueToPad.length() < size ) {

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