saving model with deep association belonging to both higher models - cakephp

Question

I have three tables, Articles, Comments, and Tags.
Tags belong to both Articles and Comments.
$this->Articles->patchEntity($entity, $this->request->getData(), [
'associated' => ['Comments.Tags']
]);
with the following error:
SQLSTATE[HY000]: General error: 1364 Field 'article_id' doesn't have a default value
Please try correcting the issue for the following table aliases:
CommentsArticles
but if I save with only 'associated' => ['Comments'] it works saving the Article and Comments with join table associations, just doesn't save any Tags.
Articles table has these associations:
$this->hasMany('Tags', [
'foreignKey' => 'article_id'
]);
$this->belongsToMany('Comments', [
'foreignKey' => 'article_id',
'targetForeignKey' => 'comment_id',
'joinTable' => 'comments_articles'
]);
Comments table has these associations:
$this->hasMany('Tags', [
'foreignKey' => 'comment_id'
]);
$this->belongsToMany('Articles', [
'foreignKey' => 'comment_id',
'targetForeignKey' => 'article_id',
'joinTable' => 'comments_articles'
]);
and Tags table has these associations:
$this->belongsTo('Comments', [
'foreignKey' => 'comment_id',
'joinType' => 'INNER'
]);
$this->belongsTo('Articles', [
'foreignKey' => 'article_id',
'joinType' => 'INNER'
]);
This is the entity after patching looks like this.
object(App\Model\Entity\Article) {
'title' => 'example article name',
'users' => [
'_ids' => []
],
'comments' => [
(int) 0 => object(App\Model\Entity\Comment) {
'id' => (int) 1,
'content' => 'this is a comment',
'tags' => [
(int) 0 => object(App\Model\Entity\Tag) {
'name' => 'example tag name',
'[new]' => true,
'[accessible]' => [
'comment_id' => true,
'article_id' => true,
'comment' => true,
'article' => true
],
'[dirty]' => [
'name' => true
],
'[original]' => [],
'[virtual]' => [],
'[hasErrors]' => false,
'[errors]' => [],
'[invalid]' => [],
'[repository]' => 'Tags'
}
],
'[new]' => false,
'[accessible]' => [
'content' => true,
'tags' => true,
'articles' => true
],
'[dirty]' => [
'tags' => true
],
'[original]' => [
'tags' => [
(int) 0 => [
'name' => '0'
]
]
],
'[virtual]' => [],
'[hasErrors]' => false,
'[errors]' => [],
'[invalid]' => [],
'[repository]' => 'Comments'
}
],
'[new]' => true,
'[accessible]' => [
'title' => true,
'tags' => true,
'comments' => true,
'users' => true
],
'[dirty]' => [
'title' => true,
'users' => true,
'comments' => true
],
'[original]' => [
'users' => []
],
'[virtual]' => [],
'[hasErrors]' => false,
'[errors]' => [],
'[invalid]' => [],
'[repository]' => 'Articles'
}

Answer 1

CaekPHP doesn't support that, it can only populate foreign keys of direct associations / in one direction. You could for example:
prepopulate the foreign key fields (which will of course only work when the article and/or comment already exists)
manually save the tags separately using the primary keys of the article and comment records
create association classes that pass the article primary key into the options when saving the article, and uses that to populate the article_id field when saving the tag
hook into the saving process on table level to pass on the article primary key and populate the tags with it
Here's a quick and dirty example for the latter solution, which should also give you an idea on how it could work on association level:
In ArticlesTable:
public function beforeSave(
\Cake\Event\Event $event,
\Cake\Datasource\EntityInterface $entity,
\ArrayObject $options
) {
if (isset($options['Articles.id'])) {
unset($options['Articles.id']);
}
}
protected function _onSaveSuccess($entity, $options)
{
if ($options['_primary']) {
$options['Articles.id'] = $entity->get('id');
}
return parent::_onSaveSuccess($entity, $options);
}
In TagsTable:
public function beforeSave(
\Cake\Event\Event $event,
\Cake\Datasource\EntityInterface $entity,
\ArrayObject $options
) {
if (!$options['_primary'] &&
isset($options['Articles.id'])
) {
$entity->set('article_id', $options['Articles.id']);
}
}