CakePHP 4: How to add count of association results to where conditions - mysql

Question

I'm trying to add the count results of an association to the where conditions, for example:
$findQuery = $this->Products->find('all');
$findQuery->leftJoinWith('Synonyms', function($q) {
return $q->where(['Synonyms.title LIKE' => '%TEST%']);
});
$findQuery->select([
'amount_of_matching_synonyms' => $findQuery->func()->count('Synonyms.id')
]);
$findQuery->where([
'OR' => [
'Products.description LIKE' => '%TEST%',
'amount_of_matching_synonyms >' => 0
]
]);
What happens now is that I'm getting 1 result returned with the 'amount_of_matching_synonyms' field. But this appears to have a cumulated result of all the records it should return.
Please help me out!

Answer 1

You should first figure out how to do these things in plain SQL, it will then be much easier to translate things to the query builder.
Counting related data requires joining in the realted data and creating groups on which aggregate functions can be used, and you're missing the latter. Furthermore you cannot use aggregates in the WHERE clause, as grouping happens after the WHERE clause is applied, you would have to use the HAVING clause instead.
The basic SQL to filter on such counting would look something like this:
SELECT
COUNT(synonyms.id) amount_of_matching_synonyms
FROM
products
LEFT JOIN
synonyms ON synonyms.id = synonyms.product_id
GROUP BY
products.id
HAVING
amount_of_matching_synonyms > 0
Translating this into the query builder would be fairly simple, you'd just need group() and having(), something like this:
$findQuery = $this->Products
->find()
->select([
'Products.description',
'amount_of_matching_synonyms' => $findQuery->func()->count('Synonyms.id')
])
->leftJoinWith('Synonyms', function(\Cake\ORM\Query $q) {
return $q->where(['Synonyms.title LIKE' => '%TEST%']);
})
->group('Products.id')
->having([
'OR' => [
'Products.description LIKE' => '%TEST%',
'amount_of_matching_synonyms >' => 0
],
]);
Note that you need to select the description, otherwise the condition in the having clause would fail.
The resulting SQL would look something like this:
SELECT
products.description,
COUNT(synonyms.id) amount_of_matching_synonyms
FROM
products
LEFT JOIN
synonyms ON
synonyms.product_id = products.id
AND
synonyms.title LIKE '%TEST%'
GROUP BY
products.id
HAVING
products.description LIKE '%TEST%'
OR
amount_of_matching_synonyms > 0
See also
MySQL 5.7 Reference Manual / Functions and Operators / Aggregate Functions
Cookbook > Database Access & ORM > Query Builder > Aggregates - Group and Having
Cookbook > Database Access & ORM > Query Builder > Subqueries