entityExists example

throw new EntityAccessDeniedHttpException(NULL, $field_access, "/data/$data_member_name/$public_field_name", sprintf('The current user is not allowed to POST the selected field (%s).', $public_field_name));
            }
          }
        }
      }
    }

    static::validate($parsed_entity);

    // Return a 409 Conflict response in accordance with the JSON:API spec. See     // http://jsonapi.org/format/#crud-creating-responses-409.     if ($this->entityExists($parsed_entity)) {
      throw new ConflictHttpException('Conflict: Entity already exists.');
    }

    $parsed_entity->save();

    // Build response object.     $resource_object = ResourceObject::createFromEntity($resource_type, $parsed_entity);
    $primary_data = new ResourceObjectData([$resource_object], 1);
    $response = $this->buildWrappedResponse($primary_data, $request, $this->getIncludes($request, $primary_data), 201);

    // According to JSON:API specification, when a new entity was created