Result Processors

Result Processors are used to modify the result of getting a configuration and decoding it. Each processor has an annotation @ConfigPriority so we run them in order passing the output of one Result Processor as the input to the next.

Gestalt has two core result processors ErrorResultProcessor and DefaultResultProcessor. The ErrorResultProcessor throws a GestaltException if there is an unrecoverable error. The DefaultResultProcessor will convert the result into a default value if there is no result.

To implement your own Result Processors you need to inherit from ResultProcessor.

To automatically register your own default ResultProcessor, add it to a file in META-INF\services\org.github.gestalt.config.processor.result.ResultProcessor and add the full package of classpath your ResultProcessor.

Alternatively, you can implement the interface and register it with the gestalt builder addResultProcessors(List<ResultProcessor> resultProcessorSet).

public interface ResultProcessor {

  /**
   * If your Result Processor needs access to the Gestalt Config.
   *
   * @param config Gestalt configuration
   */
  default void applyConfig(GestaltConfig config) {}

  /**
   * Returns the {@link GResultOf} with any processed results.
   * You can modify the results, errors or any combination.
   * If your post processor does nothing to the node, return the original node.
   *
   * @param results GResultOf to process.
   * @param path path the object was located at
   * @param isOptional if the result is optional (an Optional or has a default.
   * @param defaultVal value to return in the event of failure.
   * @param klass the type of object.
   * @param tags any tags used to retrieve te object
   * @return The validation results with either errors or a successful  obj.
   * @param <T> Class of the object.
   * @throws GestaltException for any exceptions while processing the results, such as if there are errors in the result.
   */
  <T> GResultOf<T> processResults(GResultOf<T> results, String path, boolean isOptional, 
                                  T defaultVal, TypeCapture<T> klass, Tags tags)
    throws GestaltException;
}