pentaho/pentaho-kettle · error · KettleException

Rest.Exception.ParamFieldEmpty

Rest.Exception.ParamFieldEmpty

Error message

Rest.Exception.ParamFieldEmpty

What it means

Thrown in calcParameters (from processRow) with message 'Parameter field is missing!': one of the configured query parameters has an empty 'field' — the row field that supplies the parameter value is blank after environment substitution.

Solutions

  1. Open the REST step's parameter table and fill in the missing 'Field' column for the flagged parameter row.
  2. Delete parameter rows that are no longer needed.
  3. Verify that any variable used in the Field column is defined so it does not resolve to an empty string.
  4. Validate the transformation before running to catch empty parameter fields at design time.

Example fix

// before (parameter row)
name="apiKey"; field=""              // throws ParamFieldEmpty
// after
name="apiKey"; field="api_key_value"
Defensive patterns

Strategy: validation

Validate before calling

// Check every parameter entry has a field before running
for (int i = 0; i < restMeta.getParameterField().length; i++) {
  String f = restMeta.getParameterField()[i];
  if (f == null || f.trim().isEmpty()) {
    throw new IllegalStateException("Parameter '" + restMeta.getParameterName()[i] + "' has no field set");
  }
}

Try / catch

try { processRow(); } catch (KettleException e) {
  if (e.getMessage().contains("Parameter field is missing")) { /* fill in the parameter table */ }
  throw e;
}

Prevention

When it happens

Trigger: meta.getParameterField()[i] is null/empty (Utils.isEmpty) for some parameter index i while query parameters are configured, during calcHeaders/calcParameters phase of processRow.

Common situations: Parameter table in the REST dialog has a row with the 'Field' column empty (only parameter name filled); a variable used as field name resolves to empty at runtime; parameters copied from another step with the value column cleared.

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/16f963a9466d124b. Report an issue: GitHub.

Appendix: source

Thrown at plugins/rest/core/src/main/java/org/pentaho/di/trans/steps/rest/Rest.java:556

  }

  /**
   * Calculate the parameters
   *
   * @throws KettleException
   */
  private void calcParameters() throws KettleException {
    // Parameters
    int nrParams = meta.getParameterField() == null ? 0 : meta.getParameterField().length;
    if ( nrParams > 0 ) {
      data.nrParams = nrParams;
      data.paramNames = new String[ nrParams ];
      data.indexOfParamFields = new int[ nrParams ];
      for ( int i = 0; i < nrParams; i++ ) {
        data.paramNames[ i ] = environmentSubstitute( meta.getParameterName()[ i ] );
        String field = environmentSubstitute( meta.getParameterField()[ i ] );
        if ( Utils.isEmpty( field ) ) {
          throw new KettleException( BaseMessages.getString( PKG, "Rest.Exception.ParamFieldEmpty" ) );
        }
        data.indexOfParamFields[ i ] = data.inputRowMeta.indexOfValue( field );
        if ( data.indexOfParamFields[ i ] < 0 ) {
          throw new KettleException( BaseMessages.getString( PKG, "Rest.Exception.ErrorFindingField", field ) );
        }
      }
      data.useParams = true;
    }

    int nrMatrixParams = meta.getMatrixParameterField() == null ? 0 : meta.getMatrixParameterField().length;
    if ( nrMatrixParams > 0 ) {
      data.nrMatrixParams = nrMatrixParams;
      data.matrixParamNames = new String[ nrMatrixParams ];
      data.indexOfMatrixParamFields = new int[ nrMatrixParams ];
      for ( int i = 0; i < nrMatrixParams; i++ ) {
        data.matrixParamNames[ i ] = environmentSubstitute( meta.getMatrixParameterName()[ i ] );
        String field = environmentSubstitute( meta.getMatrixParameterField()[ i ] );
        if ( Utils.isEmpty( field ) ) {

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