Laravel Eloquent GroupBy Name to Create array of ID's - php

Question

I have a table in my Laravel application which I wish to query.
id | company_name | contact |
-----------------------------
1 | Tesco | Name 1 |
2 | Tesco | Name 2 |
3 | Asda | Name 3 |
4 | Tesco | Name 4 |
5 | Asda | Name 5 |
I'm trying to get an array of all unique company names with all ID numbers.
'Tesco' => [1,2,4]
'Asda' => [3,5]
I have tried
$companies = Contact::select('company_name','id')->groupBy('company_name')->get();
However this requests the 'id' to be included in the group by which defeats the purpose. I understand it's asking for this because it's not a SUM or COUNT etc.
The above table may seem unusual and I know I should have a relation to a companies table however this is necessary at this stage.

Answer 1

You could use GROUP_CONCAT()
$companies = Contact::select('company_name', DB::raw('GROUP_CONCAT(id) as ids'))
->groupBy('company_name')
->get();
This would return something like:
company_name | ids
Tesco | 1,2
Edit: if you want the ids in the form an array, you could just map over the collection to convert it:
$companies->map(function($column) {
$column->ids = explode(',', $column->ids);
});
That should do the trick.