How to use

relationships

method

in

ai.grakn.concept.Role

/**
 * convert a given type to a map of relation types in which it can play roles
 * and the corresponding role types including entity type hierarchy
 * @param entryConcept to be converted
 * @return map of relation types in which it can play roles and the corresponding role types
 */
default Multimap<RelationshipType, Role> toRelationshipMultimap(T entryConcept){
  Multimap<RelationshipType, Role> relationMap = HashMultimap.create();
  toCompatibleRoles(entryConcept)
      .forEach(role -> role.relationships()
          .forEach(rel -> relationMap.put(rel, role)));
  return relationMap;
}

/**
 *
 * @param role The Role to validate
 * @return An error message if the relates does not have a single incoming RELATES edge
 */
static Optional<String> validateHasSingleIncomingRelatesEdge(Role role){
  if(!role.relationships().findAny().isPresent()) {
    return Optional.of(VALIDATION_ROLE_TYPE_MISSING_RELATION_TYPE.getMessage(role.label()));
  }
  return Optional.empty();
}

/**
 * Checks if the {@link Role} of the {@link Casting} has been linked to the {@link RelationshipType} of
 * the {@link Relationship} which the {@link Casting} connects to.
 *
 * @param role the {@link Role} which the {@link Casting} refers to
 * @param relationshipType the {@link RelationshipType} which should connect to the role
 * @param relationship the {@link Relationship} which the {@link Casting} refers to
 * @return an error if one is found
 */
private static Optional<String> roleNotLinkedToRelationShip(Role role, RelationshipType relationshipType, Relationship relationship){
  boolean notFound = role.relationships().
      noneMatch(innerRelationType -> innerRelationType.label().equals(relationshipType.label()));
  if(notFound){
    return Optional.of(VALIDATION_RELATION_CASTING_LOOP_FAIL.getMessage(relationship.id(), role.label(), relationshipType.label()));
  }
  return Optional.empty();
}