Laravel migration for update from v4 to v5 of Spatie Medialibrary

2017_11_10_194951_add_mime_type_to_media_table.php

<?php

use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Schema;
use Illuminate\Support\Facades\Storage;

class AddMimeTypeToMediaTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::table('media', function (Blueprint $table) {
            $table->string('mime_type')->after('file_name')->nullable();
        });

        DB::transaction(function () {
            $images = DB::table('media')
                ->select('id', 'file_name', 'disk')
                ->get();

            foreach ($images as $img) {
                $prefix = Storage::disk($img->disk)->getDriver()->getAdapter()->getPathPrefix();
                $mime_type = (new Finfo(FILEINFO_MIME_TYPE))->file($prefix.'/'.$img->id.'/'.$img->file_name);

                DB::table('media')
                    ->where('id', $img->id)
                    ->update(['mime_type' => $mime_type]);
            }
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::table('media', function (Blueprint $table) {
            $table->dropColumn('mime_type');
        });
    }
}