Problem/Motivation

The issue that was addressed in commit e62a1fe #3930 #3931 is back.

If you submit an empty string as DB prefix (--db-prefix='') it is handled exactly as if no db-prefix was given: the command asks for a prefix regardless of the input. This is due to a regression first introduced by f1dc3aa #3917. This regression was partly reverted by 1247f20 #4049, but in both cases PHP’s implicit type casting causes problems.

You have to check the input value explicitly against null, otherwise a blank string ("no prefix") will be handled like "no value given".

if (!$something) {
    echo '$something is either null or 0 or false or an empty array or an empty string. Are you sure this is the desired behavior?';
}

How to reproduce

• Drupal version: tested on Drupal 8.6+
• Console version: Regression was introduced in 1.9.1

drupal -y si test \
    --langcode="en" \
    --db-type="mysql" \
    --db-host="testdbhost" \
    --db-port="3306" \
    --db-name="testdb" \
    --db-user="testuser" \
    --db-pass="testpass" \
    --db-prefix="" \
    --account-name=admin \
    --account-pass=admin \
    --account-mail=admin@example.com \
    --site-name="Test (MySQL)" \
    --site-mail="admin@example.com"

Result:

 Database Prefix []:
 >

Solution

Avoid implicit type casting and check $input->getOption('db-prefix') against null explicitly.