Why doesn't unique work in Yii2 model?

Question

Yii

In general there is a console command Hello there is an action Test. when running several such processes at the same time, duplicates are obtained and the unique validation in the model does not work

public function actionTest()
    {
        $email = '[email protected]';
        $doubleModels = Test::findOne(['email' => $email]);
        if (!$doubleModels) {
            $model = new Test();
            $model->email = $email;
            $model->save();
        }
    }

And in the Test.php model there is a validation

/**
     * {@inheritdoc}
     */
    public function rules()
    {
        return [
            ['email', 'unique'],
            [['email'], 'string', 'max' => 255],
        ];
    }

to check, I made several identical task crons and simultaneously run
23 */1 * * * cd /var/www/domain/data/www; /usr/bin/php yii hello/test
23 */1 * * * cd /var/www/domain/data/www; /usr/bin/php yii hello/test
23 */1 * * * cd /var/www/domain/data/www; /usr/bin/php yii hello/test
23 */1 * * * cd /var/www/domain/data/www; /usr/bin/php yii hello/test

It turns out 4 records, although the model has a unique email field.

How to fix such jambs? so that this does not happen in working scripts

Answer 1

Try like this

public function actionTest()
    {
        $email = '[email protected]';
        $emailExists = Test::find()->where(['email' => $email])->exists();
        if (!$emailExists) {
            $model = new Test();
            $model->email = $email;
            $model->save(false);
        }
    }

Answer 2

unique makes the request itself and checks for availability, several processes manage to check and write at the same time, so on the database side we put a unique key in the email field. mail