framework/db/BaseActiveRecord.php
public function __isset($name)
    {
        try {
            return $this->__get($name) !== null;
        } catch (\Throwable $t) {
            return false;
        } catch (\Exception $e) {
            return false;
        }
    }
public function __isset($name)
    {
        try {
            return $this->__get($name) !== null;
        } catch (\Throwable $t) {
            return false;
        } catch (\Exception $e) {
            return false;
        }
    }
Checks if a property value is null.
This method overrides the parent implementation by checking if the named attribute is `null` or not.
@param string $name the property name or the event name
@return bool whether the property value is null