CakePHP 3 - DB table assocciation with itself - php

Question

I have a table in my DB that has a association with itself. I am trying to get all parent categories with their child categories, but I can't get it to work.
This is how the table looks:
id | name | description | image | is_child | forum_category_id | level
Now, obviously the "forum_category_id" is the parent id that refers to the same table.
I baked the model and this is in the table file:
$this->belongsTo('ForumCategories', [
'foreignKey' => 'forum_category_id'
]);
$this->hasMany('ForumCategories', [
'foreignKey' => 'forum_category_id'
]);
The code I use to load from DB is this:
debug($results = $this->find()
->order(['id' => 'ASC'])
->where(['is_child' => 0])
->toArray()
);
With this code, I do get the parent categories, but not the children.
So I thought to use "Contain", but that only returns empty parent categories.
debug($results = $this->find()
->order(['id' => 'ASC'])
->where(['is_child' => 0])
->contain([
'ForumCategories' => function ($q)
{
return $q
->where(['is_child' => 1]);
}
])
->toArray()
);
I have no idea how to get the child categories. I read something about using "Threaded" (no results/success so far) or the TreeBehaviour, but I don't really any idea on how to use them.
Any idea on how this is still possible is much appreciated!

Answer 1

You should use different aliases for the 2 association.
$this->belongsTo('ForumCategories', [
'foreignKey' => 'forum_category_id'
]);
$this->hasMany('ForumChildCategories', [
'className' => 'ForumCategories',
'foreignKey' => 'forum_category_id'
]);
By this $this->ForumCategories->find() will give you the parent and $this->ForumChilfCategories->find() the children.
Otherwise - if that is option - change your database schema and use tree behaviour.