Laravel: External variable in callback for chunk - php

Question

I am trying to implement search in Laravel. I want to search on models.
Since there can be many records in the database, I am trying the chunk function.
public function searchLeads($param)
{
$results = array();
// get all leads
Lead::chunk(100, function($leads) use ($results, $param) {
// search in name
$results = array_merge($results, $this->repository->searchInName($leads, $param));
// search in email
$results = array_merge($results, $this->repository->searchInEmail($leads, $param));
// and so on ...
}
// eliminate duplicates
$collection = collect($results);
$collection = $collection->unique();
$results = $collection->all();
dd($results);
// return $results;
}
Note: The searchIn... functions return array of results and are working as expected.
When I try the above code, I get an empty array. So I changed the following line (added a reference & to $results).
Lead::chunk(100, function($leads) use (&$results, $param) {
Now I get the expected output.
My question is, have I stumbled upon the right solution, or am I missing something that might introduce bugs in the code?
Note:
I know using where clause is a better and efficient way; but I cannot use where for this.

Answer 1

I got the solution after reading a bit about php closures. My real worry was that I am not using the $results array correctly.
But after reading php docs, I know I am doing it correctly.
Please note that I am aware of where clause and it's usage would be much more efficient here. But that's not what I was trying to ask.

Answer 2

to use the search, you could do something like:
$results = Lead::where('mail','like', $param)->orWhere('name','like', $param)->get();
then mysql does the search, which i believe is the fastes way of doing it.
depending on how the search should be done:
...where('mail','like', %$param%)...
https://laravel.com/docs/5.1/queries#where-clauses
else try to describe what the end goal of your search is?