Craft CMS 3 content migrations - create field

gistfile1.txt

<?php

namespace craft\contentmigrations;

use Craft;
use craft\db\Migration;

/**
 * m170831_195046_second_migration migration.
 */
class m170831_195046_field_migration extends Migration
{
    /**
     * @inheritdoc
     */
    public function safeUp()
    {
        $fieldsService = Craft::$app->getFields();

        $field = $fieldsService->createField([
            'type' => 'craft\fields\PlainText',
            'groupId' => 1,
            'name' => 'Test field',
            'handle' => 'testField',
            'instructions' => '',
            'translationMethod' => 'none',
            'translationKeyFormat' => NULL,
            'settings' => [
                'placeholder' => 'Type here',
                'charLimit' => '',
                'multiline' => '',
                'initialRows' => '4',
                'columnType' => 'text',
            ],
        ]);

        $success = $fieldsService->saveField($field);

        return $success;
    }

    /**
     * @inheritdoc
     */
    public function safeDown()
    {
        $field = Craft::$app->getFields()->getFieldByHandle('testField');

        $success = Craft::$app->getFields()->deleteFieldById($field->id);
        
        return $success;
    }
}