Use identifier in PHP and how does it affect the logic

Question

Use identifier is used when we want to send some outer environment variables inside closures so I have a scenario.

$invoiceList = UserInvoice::where('user_id', $this->user->id)
            ->where(function ($query) use ($filters) {
                $query->where('invoice_number', 'LIKE', "%{$filters['invoiceNumber']}%")
                    ->when($filters['type'], function ($query) use ($filters) {
                        $query->whereIn('invoice_type', $filters['type']);
                    });
            });

In this Laravel eloquent query I have checked for filter['type'] when it is there then try to filter my invoice_type from filter[type]

But I am now confused here that what if I pass filters inside functions parameters like this

method 1 

->when($filters['type'], function ($query,$filters) use () {
                        $query->whereIn('invoice_type', $filters['type']);
                    });

Or

method 2 

->when($filters['type'], function () use ($query,$filters) {
                        $query->whereIn('invoice_type', $filters['type']);
                    });

What impact would it be if I opt these methods I have also tried both and in method 1 it throws me an error that filters['type'] not available and when I tried method 2 it works fine so please can any one explain how does it works I mean not theoretically but in practical language what basically happening there. Also where it is defined that a closure function will accept how many numbers of arguments

Answer 1

The very last thought in your question is actually the key to your misunderstanding:

where it is defined that a closure function will accept how many numbers of arguments

The answer is wherever the function is eventually executed.

In this case, you are passing the function to the when method; that method can decide when to execute it, and what parameters to pass when it does. We can look at the source code directly and see what happens:

public function when($value, callable $callback = null, callable $default = null)
{
    // some extra logic skipped as not relevant right now

    if ($value) {
        return $callback($this, $value) ?? $this;
    } elseif ($default) {
        return $default($this, $value) ?? $this;
    }

    return $this;
}

So, if $value is "truthy", $callback will be executed with exactly two parameters: the current object ($this) and the exact value provided ($value). In this case, that will be the query you're building, and the value of $filters['type'].

Think of it like handing over an envelope: you don't have any control of what the when method puts into the envelope, you just get to look at it once it's there.