CakePHP 3 join on a secondary key using ORM - cakephp-3.0

Question

CakePHP 3.5.13 - working with a legacy database. I have a table called substances where the primary key is id. There is also another column in this table called app_id.
The majority of tables in the application have a foreign key which means they can be joined to substances.id. There is one table called article_95 which has a field article_95.app_id and therefore the join must be made to substances.app_id (not substances.id - there is no reference to that field inside the article_95 table at all).
The application performs a search based on up to 11 inputs. I'm using the ORM to dynamically build the query object before executing it.
I begin my query like this:
$query = $Substances->find()->select(['id' => 'Substances.id'])->distinct();
Then if I wanted to do something where the join maps to substances.id, I'm doing it like this:
// Search by CAS Number
if ($this->request->getData('cas_number')) {
$cas_number = $this->request->getData('cas_number');
$query = $query->matching('Cas', function ($q) use ($cas_number) {
return $q->where([
'Cas.value LIKE' => '%'.$cas_number.'%'
]);
});
}
So far so good. If I output the SQL string it looks like this:
'SELECT DISTINCT Substances.id AS `id` FROM substances Substances INNER JOIN cas_substances CasSubstances ON Substances.id = (CasSubstances.substance_id) INNER JOIN cas Cas ON (Cas.value like :c0 AND Cas.id = (CasSubstances.cas_id))'
My problem comes with how to manipulate the query object when it comes to my article_95 table, because it's trying to join on substances.id when I need it to join on substances.app_id.
I have the following in my Table classes. Please note the line $this->setPrimaryKey('tbl_id'); - this is because I'm using a legacy/old database and the primary key of the article_95 table is actually tbl_id not id. However this is relatively insignificant because the join should be based on app_id which exists in both tables.
// src/Model/Table/SubstancesTable.php
public function initialize(array $config)
{
$this->setTable('substances');
$this->setPrimaryKey('id');
$this->hasMany('Article95s', [
'foreignKey' => 'app_id'
]);
// ...
}
// src/Model/Table/Article95sTable.php
public function initialize(array $config)
{
$this->setTable('article_95');
$this->setPrimaryKey('tbl_id');
$this->belongsTo('Substances', [
'foreignKey' => 'app_id',
'joinType' => 'INNER'
]);
}
If I try and do a search which include an Article 95 value the SQL string becomes like this:
'SELECT DISTINCT Substances.id AS `id` FROM substances Substances INNER JOIN cas_substances CasSubstances ON Substances.id = (CasSubstances.substance_id) INNER JOIN cas Cas ON (Cas.value like :c0 AND Cas.id = (CasSubstances.cas_id)) INNER JOIN article_95 Article95s ON (Article95s.entity_name like :c1 AND Substances.id = (Article95s.app_id))'
The problem with this is the part of the SQL string which reads Substances.id = (Article95s.app_id)). I need that to be Substances.app_id = (Article95s.app_id)) but I don't know how to write this with the ORM syntax.
It's also important that the rest of the joins (e.g. CAS Number shown previously) remain joined on substances.id.
Please can someone help?

Answer 1

the manual explain it all
belongsTo
bindingKey: The name of the column in the other table, that will be used for matching the foreignKey. If not specified, the primary key (for example the id column of the Users table) will be used.
$this->belongsTo('Substances', [
'foreignKey' => 'app_id',
'bindingKey' => 'app_id',
'joinType' => 'INNER'
]);
hasMany
bindingKey: The name of the column in the current table, that will be used for matching the foreignKey. If not specified, the primary key (for example the id column of the Articles table) will be used.
$this->hasMany('Article95s', [
'foreignKey' => 'app_id',
'bindingKey' => 'app_id',
]);