Middlewares

It’s a middlewares emulator for MODx Revolution based on classes. But not only. In addition you can use class-based listeners instead of usual plugins.

Middlewares

Middlewares can be used to handle the request, and also allow you to perform certain actions after the response is prepared.

Middlewares are based on classes. They can be global (fires on every request) or custom (fires only for specified resources). The global middlewares are specified in the “middlewares_global_middlewares” system setting. The custom ones must be set in a resource TV with name “middlewares”.
The middleware class has 3 methods:

• onRequest - called on the OnMODXInit event.
• beforeResponse - called on the OnWebPagePrerender event.
• afterResponse - called on the OnWebPageComplete event.

Usage

Let’s create a global middleware. Create a file in the folder core/middlewares/. Let’s call it global.php.

<?php 
// global.php
class GlobalMiddleware extends Middlewares\Middleware
{
    public function onRequest() 
    {
        $this->modx->log(1, 'Save this message in the error log.');
    }
    public function beforeResponse() 
    {
        // Change the output
        $this->modx->resource->_output = 'New content for output';
    }
    public function afterResponse() {}
}
// If the class name and file name do not match, then you need to return the class name.
return 'GlobalMiddleware';

In the next step we need to specify the file name without extension (“global”) in the “middlewares_global_middlewares” system setting. That’s all.

The “contexts” property is intended to specify contexts in which the middleware will be work.

// By default the web context is set.
public $contexts = array('web');

Specify an empty array to ignore context checking.

Run a middleware manually

$class = app('MiddlewareService')->loadMiddlewareClass('CsrfMiddleware');
(new $class($this->modx))->onRequest();

Listeners

Listeners (event handlers) like middlewares are classes that are located in the folder specified in the “listeners_path” system settings. By default “core/listeners”.

How to use it

Create a file in the corresponding folder. Now you need to create a public method and give it the name of the corresponding MODX event.

<?php
// ListenerManager.php
class ListenerManager extends Middlewares\Listener
{
    public $contexts = ['web', 'mgr'];
    public function OnHandleRequest() 
    {
        $this->modx->log(1, '[ListenerManager] OnHandleRequest event is fired!';
        $this->modx->regClientScript('<script>alert("OnHandleRequest");</script>');
    }
    public function OnBeforeManagerPageInit()
    {
        $this->modx->controller->addHtml('<script>alert("OnBeforeManagerPageInit");</script>');
    }
    public function OnBeforeDocFormSave($properties) 
    {
        extract($properties);
        if (empty($resource->longtitle)) {
            $this->modx->event->output('['Long title is required!'); // to modal window
            $this->modx->log(1, '[ListenerManager] Failed to save page id '.$id.' due to missing longtitle'; // to the error log
        }
    }
}
// If the class name and file name do not match, then you need to return the class name.
// In this case they are the same. So no need to return it.
// return 'ListenerManager';

Put the file name in the “middlewares_listeners” system setting. Or you can do it in the global middleware:

// global.php
class GlobalMiddleware extends Middlewares\Middleware
{
    public function onRequest() 
    {
        $this->modx->setOption('middlewares_listeners', 'ListenerManager');
    }
}
return 'GlobalMiddleware';

if you want to run your listeners before any MODX plugins, specify the argument “before” of the corresponding method:

public function OnHandleRequest($before=true) 
{
    $this->modx->log(1, '[ListenerManager] OnHandleRequest event is fired!');
    $this->modx->regClientScript('<script>alert("OnHandleRequest");</script>');
}
public function OnBeforeDocFormSave($properties, $before=true) 
{
    extract($properties);
    if (empty($resource->longtitle)) {
        $this->modx->event->output('Long title is required!'); // to modal window
        $this->modx->log(1, '[ListenerManager] Failed to save page id '.$id.' due to missing longtitle'!); // to the error log
    }
}

So in most cases you can refuse to use usual MODX plugins.

Example files

You can find a middleware file in the core/middlewares directory and a listener file in the core/listeners directory. The middleware is ready for use right after installation.

System settings

• middlewares_path - path to middlewares’ classes. By-default “{core_path}middlewares/“.
• middlewares_lpath - path to listeners’ classes. By-default, “{core_path}listeners/“.
• middlewares_global_middlewares - comma separated names of middlewares.
• middlewares_listeners - comma separated names of listeners.