Ran into a unique situation today: Running Laravel 8 with MySQL 5.5 yields some frustrating errors when migrating the database.

Laravel 8 supports MySQL 5.7+. So if you’re planning on running MySQL 5.5 (because the default Amazon Linux 2 repositories are woefully out of date), then here’s a little code you can add to your migration files to keep unique indexes from failing.

I looked around online, and couldn’t find anyone that was describing this exact situation, so I hacked together a solution.

Create a new file in app/Models/DatabaseVersion.php with the content below:

<?php

namespace App\Models;
use Illuminate\Support\Facades\DB;

class DatabaseVersion {
	static function getDBversion() {
		$label = 'version()';
		$version = DB::select("select version()")[0]->$label;
		(float)$version = mb_substr($version, 0, 6);
		return $version;
	}
}

Then in any migration files were you’re defining unique indexes, add a “use App\Models\DatabaseVersion;” and then specify the archer string length, similar to the users migration show below:

<?php

use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\Schema;
use App\Models\DatabaseVersion;

class CreateUsersTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('users', function (Blueprint $table) {
            $table->id();
            $table->string('name');
            $table->string('email',(DatabaseVersion::getDBversion() < '5.7.0'?191:255))->unique();
            $table->timestamp('email_verified_at')->nullable();
            $table->string('password');
            $table->rememberToken();
            $table->timestamps();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('users');
    }
}

The key point in the file above is this little code snippet:

$table->string('email',(DatabaseVersion::getDBversion() < '5.7.0'?191:255))->unique();

This tells Laravel to set the string length to 191 characters instead of 255 for MySQL versions less than 5.7. This is critical because earlier versions of MySQL will fail when trying to create unique indexes with utf-8 varchar(255) fields.