framework/db/mysql/ColumnSchema.php
public function phpTypecast($value)
    {
        if ($value === null) {
            return null;
        }

        if (!$this->disableJsonSupport && $this->type === Schema::TYPE_JSON) {
            return json_decode($value, true);
        }

        return parent::phpTypecast($value);
    }
public function phpTypecast($value)
    {
        if ($value === null) {
            return null;
        }

        if (!$this->disableJsonSupport && $this->type === Schema::TYPE_JSON) {
            return json_decode($value, true);
        }

        return parent::phpTypecast($value);
    }
{@inheritdoc}