Querying eloquent relationship - php

Question

I have the following set for relations in my eloquent models/db:
Student has many PhdReport
PhdReport has one Link
I need to get Students where the (single) most recent PhdReport (by the attribute date_to) is more than 6 months and the Link connected to the PhdReport has a status of 'complete'.
I am trying to do this using eloquent relationships and I'm pretty new to the concept of querying relationships so I would like to know if there's a better approach to the one I'm taking.
Here's the relevant code so far:
PhdReport.php
public function link()
{
return $this->belongsTo(\App\Models\Link::class);
}
Student.php
public function phdReport()
{
return $this->hasMany(\App\Models\PhdReport::class);
}
public function latestPhdReport()
{
return $this->hasOne(\App\Models\PhdReport::class)->latest('date_to');
}
/* this doesn't work! */
public function lastPhdReportSixMonthsAgo()
{
$sixMonthsAgo = \Carbon\Carbon::now()->subMonth(6);
return $this->whereHas('latestPhdReport', function ($query) use ($sixMonthsAgo) {
$query->where('date_to', '<=', $sixMonthsAgo);
});
}
This is my best shot at it so far but I am unsure if the first whereHas applies to the second whereHas also?
$sixMonthsAgo = \Carbon\Carbon::now()->subMonth(6);
$students = $this->student
->whereHas('phdReport.link', function ($query) {
$query->where('status', 'complete');
})
->whereHas('latestPhdReport', function ($query) use ($sixMonthsAgo) {
$query->where('date_to', '<=', $sixMonthsAgo);
})
->get();
If I run:
$students = $this->student
->has('lastPhdReportSixMonthsAgo')
->get();
I get:
BadMethodCallException in Builder.php line 1994:
Call to undefined method Illuminate\Database\Query\Builder::getRelated()
Any advice would be much appreciated!

Answer 1

This is my current solution, I haven't had time to refactor yet but I'm sure it can be improved by doing only a query and no filter. Will edit when I get time but thought I'd put it up as it might help someone else. Much credit to #JarekTkaczyk
$monthsAgo = \Carbon\Carbon::now()->subMonth($months);
// Query 1: students with a completed report
$studentsWithCompletedLink = $studentsWithCompletedLink
->whereHas('phdReport.link', function ($query) {
$query->where('status', 'complete');
})
->get();
if ($months != 0) {
// filter through to get students where the report date_to is more than $months months ago
$studentsWithReport = $studentsWithCompletedLink->filter(function ($student) use ($monthsAgo) {
return $student->latestReport->date_to <= $monthsAgo;
});
}
Student.php
public function latestPhdReport()
{
return $this->hasOne(\App\Models\PhdReport::class)->latest('date_to');
}