php - Invalid argument supplied for foreach() : Yii2

one text

Solution:

Since $plusone_subjects is not valid json, you can manually change it to valid json and then convert it to an array like so:

$plusone_subjects = "[$plusone_subjects]"; //covert string to valid json;
$plusone_subjects = json_decode($plusone_subjects,true); //covert to array

foreach ($plusone_subjects as $subject)
{
    echo $subject["subject_name"]; 
}