Question

I’m trying to create an application which should help distribute work to employees or volunteers on a irregular time schedule based on their availabilities.

Anyway, here are my models and the relations between them :

Users hasMany Jobs
Jobs belongTo Users
Users hasMany Availabilities
Availabilities belongTo Users
Jobs hasOne Periods
Periods belongTo Jobs
Availabilities hasOne Periods
Periods belongTo Availabilities

The problem is that “Periods” is on the receiving side of two hasOne relationships and, if I’m not wrong, it’s something you can’t do in CakePHP. What is the best way to proceed in this situation?

You might have also spotted the fact a “Job” may be assigned to someone (a “User”) or not. Should I drop the relationship and create it once the job has been assigned or should I create a fictional user representing “nobody” for unassigned jobs?

I would have posted a nice image but i don’t have enough reputation, sorry!
Here’s a link though.

Answer 1

The problem is that “Periods” is on the receiving side of two hasOne relationships and, if I’m not wrong, it’s something you can’t do in CakePHP. What is the best way to proceed in this situation?

I don’t see a problem. You should be able to add the foreign key for each hasOne relationship to the periods table (periods.job_id and periods.availability_id).

You might have also spotted the fact a “Job” may be assigned to someone (a “User”) or not. Should I drop the relationship and create it once the job has been assigned or should I create a fictional user representing “nobody” for unassigned jobs?

This is fine. Just set the jobs.user_id to allow null values and set up the relationship. This will allow jobs to be created without being assigned to users. After you perform a find you can check empty($results['User']) to determine if you are dealing with an unassigned job.

Users hasMany Jobs, Jobs belongTo Users, …

Just a reminder: model names should be singular (ie. User hasMany Job, Job belongsTo User, etc.)

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Also I’d like a Period to belong to either a Job or an Availability and never both at the same time. Is there a conventional way to do it?

You can write validation for that in the Period model:

$validate = array(
    'job_id' => array(
        array(
            'rule' => 'validBelongsTo',
            'message' => 'A period can either belong to a job or an availability'
        ),
    ),
);

public function validBelongsTo() {
    $hasJob          = !empty($this->data['Period']['job_id']);
    $hasAvailability = !empty($this->data['Period']['availability_id']);
    if ($hasJob && $hasAvailability) {
        return false;
    } else {
        return true;
    }
}