pentaho/pentaho-kettle · error · KettleException

AvroInput.Error.MalformedPathMap

AvroInput.Error.MalformedPathMap

Error message

AvroInput.Error.MalformedPathMap

What it means

The map-walking branch of convertToKettleValue found no remaining path parts when it needed one: the field's Avro path terminated at a MAP object but no key selector followed. The reader cannot look up a key in the map, so it throws this KettleException.

Solutions

  1. Append a key selector to the path: '$.mymap[mykey]'.
  2. If you want the whole map expanded, use the '[*]' expansion form: '$.mymap[*]'.
  3. Verify the schema: if the field genuinely is a scalar, correct the path to point at the scalar leaf.

Example fix

// before
$.attributes
// after (map is an object, key needed)
$.attributes[color]
Defensive patterns

Strategy: validation

Validate before calling

// Ensure a path that reaches a MAP node has a '[key]' after it
if (schema.getField(path).schema().getType() == Schema.Type.MAP
    && !path.matches(".*\\[.+\\]$")) {
  throw new IllegalArgumentException("Path to map needs [key]: " + path);
}

Type guard

boolean mapPathHasKey(String path, Schema fieldSchema) {
  return fieldSchema.getType() != Schema.Type.MAP
      || (path != null && path.matches(".*\\[.+\\].*$"));
}

Try / catch

try {
  Object v = reader.convertToKettleValue(...);
} catch (KettleException e) {
  if (e.getMessage().contains("MalformedPathMap")) {
    // fix the field path to include a [key] selector
  } else throw e;
}

Prevention

When it happens

Trigger: A field path ends exactly at a map node (e.g. '$.mymap' where mymap is a map), so getTempParts() is empty when the map converter runs; or the path was consumed by earlier segments leaving nothing for the map lookup.

Common situations: Typing a path that stops at a map container while selecting a non-map Pentaho output type; forgetting the '[key]' bracket after a map name; schema changed so a formerly scalar field is now a map.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/ff842e818ddcb184. Report an issue: GitHub.

Appendix: source

Thrown at plugins/avro-format/core/src/main/java/org/pentaho/di/trans/steps/avro/input/AvroNestedReader.java:443

  /**
   * Processes a map at this point in the path.
   *
   * @param map           the map to process
   * @param s             the current schema at this point in the path
   * @param ignoreMissing true if null is to be returned for user fields that don't appear in the schema
   * @return the field value or null for out-of-bounds array indexes, non-existent map keys or unsupported avro types.
   * @throws KettleException if a problem occurs
   */
  public Object convertToKettleValue( AvroInputField avroInputField,
                                      Map<Utf8, Object> map, Schema s, Schema defaultSchema, boolean ignoreMissing )
    throws KettleException {

    if ( map == null ) {
      return null;
    }

    if ( avroInputField.getTempParts().size() == 0 ) {
      throw new KettleException( BaseMessages.getString( PKG, "AvroInput.Error.MalformedPathMap" ) );
    }

    String part = avroInputField.getTempParts().remove( 0 );
    if ( !( part.charAt( 0 ) == '[' ) ) {
      throw new KettleException( BaseMessages.getString( PKG, "AvroInput.Error.MalformedPathMap2", part ) );
    }

    String key = part.substring( 1, part.indexOf( ']' ) );

    if ( part.indexOf( ']' ) < part.length() - 1 ) {
      // more dimensions to the array/map
      part = part.substring( part.indexOf( ']' ) + 1, part.length() );
      avroInputField.getTempParts().add( 0, part );
    }

    Object value = map.get( new Utf8( key ) );
    if ( value == null ) {
      return null;

View on GitHub (pinned to f3058517a1)