Avoid download empty excel redirect if collection is empty

[howdu]

Is there a way I can redirect back with error if the collection is empty?

E.g

class UserExport implements FromCollection, WithHeadings, WithMapping, WithEvents, Responsable, ShouldAutoSize {
    public function collection()
    {
        $users = User::where('name', 'no user')->all();

        if ($users->isEmpty()) {
            return Redirect::back()->withErrors(['No users could be found.']);
        }

        return $rows;
    }
}

But it doesn't handle the RedirectResponse.
Call to undefined method Illuminate\Http\RedirectResponse::all()

[patrickbrouwers]

Do a count/exist query outside of the export before you call it. And redirect there. collection() method doesn't return anything.

[howdu]

I guess but wouldn't that mean running the query twice? I like how the code for exporting is out of the controller.

I looked at using the FromQuery but for one of my exports I need to create a collection on the fly where I split data into multiple rows for one of the eloquent hasMany relationships.

[patrickbrouwers]

If you would use a count query it wouldn't fetch all rows.

Alternatively you could throw an exception in collection method