Laravel Nova Metrics Partition belongsToMany relationship - laravel

Question

I have the following data model:
(Publication) <-[belongsToMany]-> (Subscriber)
I want to create a Nova Partition Metric to display the number of Subscribers for each Publication.
The calculate method of my Partition class looks like this:
public function calculate(Request $request)
{
return $this->count($request, Subscriber::with('publications'), 'publication.id');
}
But I am getting an "unknown column" error. Anyone know how to make this work?

Answer 1

You could do something like this:
public function calculate(Request $request)
{
$subscribers = Subscriber::withCount('publications')->get();
return $this->result(
$subscribers->flatMap(function ($subscriber) {
return [
$subscriber->name => $subscriber->publications_count
];
})->toArray()
);
}

Answer 2

The count helper only allows to group by a column on model's table. It also don't allow to join tables.
If you want a more complex query, with a join and a group by column in another table, you can build your own array of results and return it with the results helper.
You can see the results helper docs here: https://nova.laravel.com/docs/1.0/metrics/defining-metrics.html#customizing-partition-colors
You should create your array (you can use eloquent or query builder here) inside the calculate function, then return that array with the results helper.
Hope this helps!

Answer 3

You can make the groupBy on publication_foreign_key in Subscriber table and edit the publication_foreign_key to publication_name using ->label() method
Like this
public function calculate(Request $request)
{
return $this->count($request, Subscriber::class, 'publication_id')
->label(function($publicationId)
{
switch($publicationId)
{
case publication_foreign_key_1 : return publication_name_1;
break;
case publication_foreign_key_2 : return publication_name_2;
break;
default: return 'Others';
}
});
}