View->context issue vs Yii::$app->modules

[jakobrosenberg]

How do we access module properties from view? Say my module has a navbar and I want the navbar displayed in submodules. So far so good.

Here is the problem, if I want the navbar to display a property from the module, I'm left with two options. I can use echo Yii::$app->modules['MyModule']->myProperty. This works fine, but it forces anyone who uses my extension to use the module name 'MyModule'. This has the potential to cause extension conflicts.

Another option is $this->context->module->myProperty. But here is the next problem. If a submodule is loaded, the context->module refers to the submodule and myProperty is no longer accessible.

At the moment I'm considering attaching my module as a component/module in the module::init() so I can access it through Yii::$app->_myModule. Would that be a correct practice?

[cebe]

What kind of submodules are added to your module? If you provide them you can add a method that makes the navbar available in all submodules. If others provide submodules for your module they may extend from a base module class created by the main module.

[qiangxue]

What is context here? Is it the navbar widget or controller?

[mgrechanik]

@jakobrosenberg , if the property name is unique among the module and it's submodules you can try this option:

$property = 'someProperty';
$value = null;
$module = $this->context->module;
do {
    if (isset($module->$property)) {
        $value = $module->$property;
        break;
    }
    $module = $module->module;
}
while($module !== null);
var_dump($value);

[jakobrosenberg]

Context here is the controller and the view file is mymodule/layouts/main.php

@cebe, that would require all submodules to be written explicitely for my module, which so far is the case for none of them.

The same problem occurs in url generation. If the navigation mymodule/layouts/main.php uses ['mycontroller/myaction'] and I include a submodule not specifically tailored to my module. I can fix it by including my module in the url ['/mymodule/mycontroller/myaction] but then it prevents anyone from using it as a submodule or under a different name.

In your basic app layout you handle this with ['label' => 'Home', 'url' => ['/site/index']] because obviously, the main app should be able to locate it's own routes regardless of the which modules we're currently visiting. Some modules have the same requirements, they provide their own layout which needs to work regardless of parent/nested modules.

@mgrechanik, I thought about extending the view and creating a function like that, similar to jQuery's closest("#specific_parent"). It feels like a hack though and I don't know if it would end up too convoluted if it has to work with urls. I'll give it a shot and see how it works.

[mgrechanik]

Maybe checking for a module's class name by get_class would be in a little better way than checking for some unique property name. (this concerns this "closest" solution).

From your explanation I have not understood what you actually expect from urls.

[jakobrosenberg]

I think ID would be better in this case as module::id is already set from the class name and it allows overriding the ID if that should ever be required.

@coredevs could you possibly add one of these two options to yii\web\Controller?

Option 1

    /**
     * Traverses through the module and its ancestors and returns the first module with a matching $id. Returns the app if not found.
     * @param $id
     * @return Module
     */
    public function module($id)
    {
        $module = $this->module;
        while ($module->module && $module->id !== $id){
            $module = $module->module;
        }
        return $module;
    }

Option 2

    /**
     * Traverses through the module and its ancestors and returns the first module with a matching $id. Returns null if not found.
     * @param $id
     * @return null|Module
     */
    public function module($id)
    {
        $module = $this->module;
        while ($module->id !== $id){
            if(($module->module)){
                $module = $module->module;
            }else {
                return null;
            }
        }
        return $module;
    }

It doesn't break functionality of the current module property, but allows us to use the existing $this->context->module to find the parent module and $this->context->module($id) to traverse to a specific module. This would be a very useful feature in modules with layouts.

[jakobrosenberg]

I concur. Get_class() is a better option as $id wasn't as flexible as I thought.

    /**
     * Traverses through the module and its ancestors and returns the first module that matches $class. Returns null if not found.
     * @param string $class
     * @return null|\yii\base\Module
     */
    public function module($class)
    {
        $module = $this->module;
        while (get_class($module) !== $class){
            if(($module->module)){
                $module = $module->module;
            }else {
                return null;
            }
        }
        return $module;
    }

[qiangxue]

@jakobrosenberg Could you please answer my question? "What is context here? Is it the navbar widget or controller?"

[cebe]

@qiangxue it is in this comment: #1452 (comment)

Context here is the controller and the view file is mymodule/layouts/main.php

[qiangxue]

Thanks, @cebe. I didn't notice this line.

Because a layout view is shared by different controllers/modules/actions, if something external needs to be accessed in the layout, it has to be global. A natural choice is the application instance. You can define the module property to set an application parameter, and within the layout, you can access the application parameter instead of trying to find out the module.

I don't think we should add the module search function in the core, unless there are other convincing use cases for it.

[jakobrosenberg]

@qiangxue that's true, but it doesn't solve the url handling.

Here's my use case;

$module = $this->context->module('MyModule');
$path = "/$module->uniqueId/";

Nav::Widget([
    'items' => [
        ['label'=>'Index', 'url'=>[$path.'default/index']],
        ['label'=>'Index', 'url'=>[$path.'submodule/default/index']]

Without the path, any child modules nested in the layout would mess up the urls. If you're creating an extension, hardcoding the urls aren't an option, unless you want to force users of your extension to use a predefined route for the module.

Either modules shouldn't affect layout files of parent modules or there should be a way to get the route for the parent module. If not, anyone who wants to use a layout for a child module will have to come up with a hack. It's a lot of reinventing the wheel and browsing through source code.

Layouts are not relative to the controller like other view files, they're relative to their specific module and should have a way of accessing it without using a hack. This applies in most, if not all cases. The app main layout has hardcoded urls for this very reason, that layout urls are not relative to nested modules.

[qiangxue]

Will consider exposing the owner module to the layout view.

[qiangxue]

@yiisoft/core-developers I'm thinking about adding a static property yii\base\Module::$instance.

The issue reported here is a more generic one, not limited to layouts. Code within a module may need to access the module instance. Currently, this can only be done through Controller::module. However, when there are nested modules, this approach is not safe because you may get a child module instance.

The drawback of having Module::$instance is during a request, there could be multiple instances of the same module. But I think this is extremely rare and can be ignored.

What do you think?

[cebe]

at which point will this instance be populated? is it something like Yii::$app which is set in constructor of application class?

[qiangxue]

It will be populated when Module::getModule() is called the first time for a module.

[cebe]

sounds okay to me.

[samdark]

Is it always a module whose controller is currently running or not? getModule() could be used on a child module. Wouldn't that create a mess?

[cebe]

Well, of course we have to set CustomModelClass::$instance for each module than the static property of the base Module.

[zelenin]

How I can get module ID in bootstrap file? Module not initialised yet and no way get.ID

    public function bootstrap($app)
    {
        if ($app instanceof \yii\web\Application && $module = Module::getInstance()) {
            $moduleId = $module->id; // not work because $module === null
            $app->getUrlManager()->addRules([
                'translations/<id:\d+>' => $moduleId . '/default/update',
                'translations' => $moduleId . '/default/index',
            ], false);
        }
    }

[cebe]

this feature is to access the module when it is currently active i.e. running a controller action. Getting the id in bootstrap is not possible because it is not initialized.

[dizews]

@zelenin you can use:

$app->getUrlManager()->addRules([
      $this->id => $this->id,
      $this->id . '/<controller:\w+>/<action:\w+>' => $this->id . '/<controller>/<action>',
], false);

[zelenin]

@dizews it's in bootstrap file, not in module.
https://github.com/zelenin/yii2-i18n-module/blob/master/Bootstrap.php