Laravel Cannot use $this Inside Anonymous Function

Question

I am using a construct to get request variables only once, since I need to use them in more than one method, I do not want to repeat code.

public function __construct(Request $request)
{
    $this->labelId   = $request->label;
    $this->statusId  = $request->status;
    $this->monthId   = $request->month;
}

This works for my "standard" view, but not for the "label view":

public function standard()
{
    $appointments = Appointment::latest('start')->status($this->statusId)->label($this->labelId)->month($this->monthId)->get();

    return view('appointments.index', compact('appointments'));
}

public function label(Request $request)
{
    $appointments = Label::with(['appointments' => function ($query) use ($this->labelId, $this->statusId, $this->monthId) {
        $query->label($this->labelId)->status($this->statusId)->month($this->monthId)->get();
    }])->get();

    return view('appointments.label', compact('appointments'));
}

I am getting the error:

Cannot use $this as lexical variable

And the issue is here:

function ($query) use ($this->labelId, $this->statusId, $this->monthId)

My question is this, can I somehow use the variables anyway in the label method using the construct, or is there maybe a better way to accomplish this?

score 4 · Accepted Answer · edited May 23 '17 at 10:27

4

Replace:

$appointments = Label::with(['appointments' => function ($query) use ($this->labelId, $this->statusId, $this->monthId) {
    $query->label($this->labelId)->status($this->statusId)->month($this->monthId)->get();
}])->get();

With:

$appointments = Label::with(['appointments' => function ($query) {
    $query->label($this->labelId)->status($this->statusId)->month($this->monthId)->get();
}])->get();

You can't pass properties of the current object via use(), and you can't use($this), however, $this is always available in PHP 5.4+.

For this to work properly, you'll need PHP 5.4+. PHP 5.3 and below had a limitation where the local object context cannot be accessed from inside an anonymous function.

It is not possible to use $this from anonymous function before PHP 5.4.0

You could do something like:

$instance = $this;
$appointments = Label::with(['appointments' => function ($query) use ($instance) { // ... }

But then you couldn't access private or protected members; it would be seen as a public access. You really need PHP 5.4 :)

edited May 23 '17 at 10:27

Community

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answered Jan 22 '16 at 22:30

Will

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Awesome, thanks a lot :) Edit: Unfortunately I am getting the same error. But I will look into this. – Hardist Jan 22 '16 at 22:41
No problem. What version of PHP is this? – Will Jan 23 '16 at 00:23
Yeah I am using php 5.6 :P And if I use `$instance` it's the same as just using `$request` so :) I need to just think of another solution – Hardist Jan 23 '16 at 07:43
Ok, check out my latest edit. Just take off the `use()` entirely. As explained [here](http://stackoverflow.com/a/19433321/145279). – Will Jan 23 '16 at 07:54

Laravel Cannot use $this Inside Anonymous Function

1 Answers1