Valet switch PHP version with these commands
Install PHP 5.6 and switch Valet to PHP 5.6
valet stop
brew unlink php71
brew install php56
brew install php56-mcrypt
For the scenario, imagine posts has a foreign key user_id referencing users.id
public function up()
{
Schema::create('posts', function(Blueprint $table) {
$table->increments('id');
$table->string('title');
$table->text('body');