PermissionModel::define PHP Method

    public function define($PermissionNames, $Type = 'tinyint', $JunctionTable = null, $JunctionColumn = null)
    {
        $PermissionNames = (array) $PermissionNames;
        $Structure = $this->Database->structure();
        $Structure->table('Permission');
        $DefaultPermissions = array();
        $NewColumns = array();
        foreach ($PermissionNames as $Key => $Value) {
            if (is_numeric($Key)) {
                // Only got a permissions name with no default.
                $PermissionName = $Value;
                $DefaultPermissions[$PermissionName] = 2;
            } else {
                $PermissionName = $Key;
                if ($Value === 0) {
                    // "Off for all"
                    $DefaultPermissions[$PermissionName] = 2;
                } elseif ($Value === 1) {
                    // "On for all"
                    $DefaultPermissions[$PermissionName] = 3;
                } elseif (!$Structure->columnExists($Value) && array_key_exists($Value, $PermissionNames)) {
                    // Mapped to an explicitly-defined permission.
                    $DefaultPermissions[$PermissionName] = $PermissionNames[$Value] ? 3 : 2;
                } else {
                    // Mapped to another permission for which we don't have the value.
                    $DefaultPermissions[$PermissionName] = "`{$Value}`";
                }
            }
            if (!$Structure->columnExists($PermissionName)) {
                $Default = $DefaultPermissions[$PermissionName];
                $NewColumns[$PermissionName] = is_numeric($Default) ? $Default - 2 : $Default;
            }
            // Define the column.
            $Structure->column($PermissionName, $Type, 0);
        }
        $Structure->set(false, false);
        // Detect an initial permission setup by seeing if our placeholder row exists yet.
        $DefaultRow = $this->SQL->select('*')->from('Permission')->where('RoleID', 0)->where('JunctionTable is null')->orderBy('RoleID')->limit(1)->get()->firstRow(DATASET_TYPE_ARRAY);
        // If this is our initial setup, map missing permissions to off.
        // Otherwise we'd be left with placeholders in our final query, which would cause a strict mode failure.
        if (!$DefaultRow) {
            $DefaultPermissions = array_map(function ($Value) {
                // All non-numeric values are converted to "off" flag.
                return is_numeric($Value) ? $Value : 2;
            }, $DefaultPermissions);
        }
        // Set the default permissions on the placeholder.
        $this->SQL->set($this->_backtick($DefaultPermissions), '', false)->replace('Permission', array(), array('RoleID' => 0, 'JunctionTable' => $JunctionTable, 'JunctionColumn' => $JunctionColumn), true);
        // Set the default permissions for new columns on all roles.
        if (count($NewColumns) > 0) {
            $Where = array('RoleID <>' => 0);
            if (!$JunctionTable) {
                $Where['JunctionTable'] = null;
            } else {
                $Where['JunctionTable'] = $JunctionTable;
            }
            $this->SQL->set($this->_backtick($NewColumns), '', false)->put('Permission', array(), $Where);
        }
        // Flush permissions cache & loaded schema.
        $this->clearPermissions();
        if ($this->Schema) {
            // Redefine the schema if it has been defined to reflect the permissions that were just added.
            $this->Schema = null;
            $this->defineSchema();
        }
    }

 /**
  * Apply database structure updates
  */
 public function structure()
 {
     $PM = new PermissionModel();
     $PM->define(array('Plugins.PostUrl.Allow' => 'Plugins.PostUrl.Allow'));
     $Structure = Gdn::structure();
     $Structure->table('PostUrl')->column('DiscussionID', 'int(11)', false, 'unique')->column('PostUrlValue', 'int(11)')->column('DateInserted', 'datetime')->set(false, false);
 }