pentaho/pentaho-kettle · error · KettleValueException

: I don't know how to convert a boolean to a timestamp.

Error message

 : I don't know how to convert a boolean to a timestamp.

What it means

ValueMetaTimestamp.getTimestamp() refuses to convert Boolean source values: the TYPE_BOOLEAN case unconditionally throws this KettleValueException because PDI defines no boolean-to-timestamp mapping. The message is prefixed with the field's toString() so you can see which field was involved.

Solutions

  1. Align the metadata with the actual data: if the value is Boolean, keep the field type TYPE_BOOLEAN, or convert the source to a Timestamp-compatible type (String/Date) first with a 'Value Mapper' or 'Calculator' step.
  2. In code, branch on valueMeta.getType() and only call getTimestamp() for convertible types (String, Number, Integer, BigNumber, Date); handle Boolean explicitly with your own rule.
  3. If you own the data, change the upstream step so it emits a real timestamp (e.g. TODATE() or a Calculator conversion) instead of a boolean.
  4. As a last resort, subclass or wrap the ValueMeta and override getTimestamp() to define a custom boolean->timestamp mapping, though explicit pre-conversion is preferred.

Example fix

// before
Timestamp t = meta.getTimestamp( booleanObject ); // always throws
// after
if ( meta.getType() == ValueMetaInterface.TYPE_BOOLEAN ) {
  Boolean b = meta.getBoolean( booleanObject );
  Timestamp t = b != null && b ? new Timestamp( 0L ) : null; // explicit rule
} else {
  Timestamp t = meta.getTimestamp( booleanObject );
}
Defensive patterns

Strategy: type-guard

Validate before calling

if ( meta.getType() == ValueMetaInterface.TYPE_BOOLEAN ) {
  // do not call getTimestamp(); convert the boolean explicitly first
}

Type guard

boolean isTimestampConvertible( ValueMetaInterface meta ) {
  switch ( meta.getType() ) {
    case ValueMetaInterface.TYPE_TIMESTAMP:
    case ValueMetaInterface.TYPE_DATE:
    case ValueMetaInterface.TYPE_STRING:
    case ValueMetaInterface.TYPE_NUMBER:
    case ValueMetaInterface.TYPE_INTEGER:
    case ValueMetaInterface.TYPE_BIGNUMBER:
      return true;
    default:
      return false; // BOOLEAN, BINARY, SERIALIZABLE are not convertible
  }
}

Try / catch

try {
  t = meta.getTimestamp( value );
} catch ( KettleValueException e ) {
  if ( e.getMessage().contains( "convert a boolean to a timestamp" ) ) {
    Boolean b = meta.getBoolean( value );
    t = ( b != null && b ) ? new Timestamp( 0L ) : null; // explicit mapping
  } else { throw e; }
}

Prevention

When it happens

Trigger: getTimestamp(object) invoked on a ValueMetaTimestamp whose internal type is TYPE_BOOLEAN, i.e. the value metadata claims the source data is a Boolean, regardless of storage type.

Common situations: A stream field previously Boolean was re-declared as Timestamp while data is still boolean; generic row-copying code that calls getTimestamp for every field without checking the declared type; merge/join steps mixing metadata from two sources with conflicting types.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/4834b94c62127d49. Report an issue: GitHub.

Appendix: source

Thrown at core/src/main/java/org/pentaho/di/core/row/value/ValueMetaTimestamp.java:186

            return convertIntegerToTimestamp( (Long) convertBinaryStringToNativeType( (byte[]) object ) );
          case STORAGE_TYPE_INDEXED:
            return convertIntegerToTimestamp( (Long) index[ ( (Integer) object ).intValue() ] );
          default:
            throw new KettleValueException( toString() + " : Unknown storage type " + storageType + " specified." );
        }
      case TYPE_BIGNUMBER:
        switch ( storageType ) {
          case STORAGE_TYPE_NORMAL:
            return convertBigNumberToTimestamp( (BigDecimal) object );
          case STORAGE_TYPE_BINARY_STRING:
            return convertBigNumberToTimestamp( (BigDecimal) convertBinaryStringToNativeType( (byte[]) object ) );
          case STORAGE_TYPE_INDEXED:
            return convertBigNumberToTimestamp( (BigDecimal) index[ ( (Integer) object ).intValue() ] );
          default:
            throw new KettleValueException( toString() + " : Unknown storage type " + storageType + " specified." );
        }
      case TYPE_BOOLEAN:
        throw new KettleValueException( toString() + " : I don't know how to convert a boolean to a timestamp." );
      case TYPE_BINARY:
        throw new KettleValueException( toString() + " : I don't know how to convert a binary value to timestamp." );
      case TYPE_SERIALIZABLE:
        throw new KettleValueException( toString()
          + " : I don't know how to convert a serializable value to timestamp." );

      default:
        throw new KettleValueException( toString() + " : Unknown type " + type + " specified." );
    }
  }

  public int compare( Object data1, Object data2 ) throws KettleValueException {
    Timestamp timestamp1 = getTimestamp( data1 );
    Timestamp timestamp2 = getTimestamp( data2 );
    int cmp = 0;
    if ( timestamp1 == null ) {
      if ( timestamp2 == null ) {
        cmp = 0;

View on GitHub (pinned to f3058517a1)