inspection2.php

public function edit(int $id) {
   $this->loadModel('results');
   
   if ( $id ) {
      $entity = $this->results->find()->where(['id' => $id]);
   } else {
      $entity = $this->results->newEntity();
   }
   
   $requestData = $this->request->getData();
   
   $this->loadModel('results.Attachments');
   $AttachmentsModel = $this->Attachments;
   
   $attachments = array();
   if ( $this->request->getData() ) {
       // upload to third party
       foreach ($this->request->getData('files') as $file) {
          // code
          $attachments[] = [
            'file_id' => $file_id,
            'id' => $id
          ];
       }
       $requestData['attachments'] = $attachments;
       $patchedEntity = $this->results>patchEntity(
          $entity,
          $requestData,
          // NOT USED APPARENTLY [ 'associated' => 'attachments' ]
       );
       $errors = $patchedEntity->errors();
       if ( empty ( $errors ) ) {
            if ( !$this->results->save($entity, [
                /* NOT USED APPARENTLY
                'associated' => [
                    'attachments'
                ]*/
            ]);
       }
   }
   
}

ResultsTable.php:

$this->hasMany('Attachments', [
    'className' => 'Results.Attachments',
    'foreignKey' => 'result_id'
]);

ResultsAttachments.php:

$this->belongsTo('Results', [
    'className' => 'Results',
    'foreignKey' => 'result_id'
]);