Routing: JComponentRouterRulesMenu to find right Itemid

[Hackwar]

This rule implements finding the right Itemid as a generic rule for all component routers that extend from JComponentRouterView. It makes most of the parts of the *HelperRoute classes obsolete.

How to test

• Apply this change
• Change the router of com_content by replacing

class ContentRouter extends JComponentRouterBase
{

with

class ContentRouter extends JComponentRouterView
{
    function __construct($app = null, $menu = null) {

        $categories = new JComponentRouterViewconfiguration('categories');
        $categories->setKey('id');
        $this->registerView($categories);
        $category = new JComponentRouterViewconfiguration('category');
        $category->setKey('id')->setParent($categories, 'id')->setNestable()->addLayout('blog');
        $this->registerView($category);
        $article = new JComponentRouterViewconfiguration('article');
        $article->setKey('id')->setParent($category, 'catid');
        $this->registerView($article);
        $this->registerView(new JComponentRouterViewconfiguration('archive'));
        $this->registerView(new JComponentRouterViewconfiguration('featured'));
        $this->registerView(new JComponentRouterViewconfiguration('form'));

        parent::__construct($app, $menu);
        $this->attachRule(new JComponentRouterRulesMenu($this));
    }

    public function getCategorySegment($id, $query)
    {
        $category = JCategories::getInstance($this->getName())->get($id);
        if ($category)
        {
            return array_reverse($category->getPath());
        }

        return array();
    }

    public function getCategoriesSegment($id, $query)
    {
        return $this->getCategorySegment($id, $query);
    }

    public function getArticleSegment($id, $query)
    {
        return array($id);
    }

• Comment line 62 and 111 from /components/com_content/helpers/route.php to disable the lookup of the Itemid there.
• See that the right menu items are still found for the items

This was updated on May 22nd 2015. All discussions prior to that point have either been integrated or are obsolete.

This was made possible through the generous donation of the people mentioned in the following link via an Indiegogo campaign: http://joomlager.de/crowdfunding/5-contributors

[johanjanssens]

@Hackwar By having this method your are coupling the categories implementation to the routing API. Do we need to have a this method here ? Wouldn't this be something either for a more specialised router that understands categories, or for a specific implementation in a component router ?

[Hackwar]

I'm indeed pondering if this method should be there or not. As I wrote in the description, I'm interested in having get methods to retrieve the necessary data and this would be one of those methods. Right now, most of our core frontend components need this method and a lot of third party extensions work with categories, too. So I could either have this here or implement another class between this one and the actual router to simply implement that class. Trying to strike a balance here between abstraction and over-engineering, I put it in this class. Also, I could quite frankly not come up with yet another class name for such an intermediate class. 😉

Now, I would leave it at that, you would move it into its own class, so I would call for a third party to cast a vote what to do. 😄

[johanjanssens]

Could these methods not be exposed by the rules JComponentRouterRulesCategory object. If they need to be accessible through the router you could use magic calls to get them making the rules object work like a mixin. That gives you flexibility without cluttering the initial router.

[Hackwar]

No, the get"ViewName" methods need to be accessible from inside other rules and thus have to be implemented in the router. If you, as a dev that needs to modify an existing routers, need other methods (for example when you add your own view to a component) you can create your own router which extends from the component router and set it with JRouterSite::setComponentRouter() as a replacement for the original one.

I thought about using magic calls, but I have the feeling that this complicates the implementation again and makes it less intuitive. Joomla devs are not used to that...

[johanjanssens]

@Hackwar Would consider calling this method registerView() instead of register to better declare it's purpose. All other view related methods in the proposed API also have 'View' in their name which makes it easier to see the correlation between the methods.

[Hackwar]

Will do.

[johanjanssens]

Great!

[johanjanssens]

@Hackwar see my other comment about the getCategory() method. If you don't add it you also don't need to add the getName() method. Additionally you could ask yourself if this method has use outside of the implementation as proposed in getCategory(). If not it might be better to remove this and implement the logic in getCategory().

[Hackwar]

This method has a use outside of JCategories. It is also used to find the right menu items for the lookup and for other filter tasks that we have. Yes, it is named like our magic getters, but consider it one of the reserved words that can not be used as a name for a view.

[johanjanssens]

In that case, maybe consider giving the method a protected scope and renaming it to getRouterName() to allow the router to have a getName() method if it needs to ? Otherwise this becomes a need to know that you cannot expose a 'name' property in your routes ?

[johanjanssens]

@Hackwar By making the property public you are allowing it to be changed from the outside. Is that intentional ? Couldn't this result in unwanted side effects ?

[Hackwar]

That is indeed unintentional. How could that slip through? Thanks, will change.

[johanjanssens]

Thanks!

[johanjanssens]

@Hackwar Bit of a code smell here. You should try to check against and interface and not an implementation. This gives developers more flexibility, Eg would be better if it would be

public function __construct(JComponentRouterAdvancedInterface $router)

[Hackwar]

I choose the concrete implementation, because the rules are pretty tightly coupled to this class. I also again tried to find a balance between abstraction and over-engineering. My heart is not attached to this, but I'd rather not add another folder to this one simply to stuff the interface in there for the autoloader...

As with the last cases, I'm happy to be overruled by similar opinions.

[johanjanssens]

Typo, should have been public function __construct(JComponentRouterInterface $router)Additionally would consider adding this to the JComponentRouterRulesInterface to enforce the constructor.

[Hackwar]

JComponentRouterInterface does not have the interface that is required by the rules. You definitely need an interface like JComponentRouterAdvanced. Remember that this advanced router is optional. If a component doesn't want it, we are not forcing it upon the devs. So JComponentRouterInterface does not have the features that are required for the advanced component router.

[johanjanssens]

@Hackwar I understand, it would still be good to have an interface for this so we don't need to work against an implementation. Can we move the API as defined in the advanced router into an interface ?

[johanjanssens]

@Hackwar Do you want to allow this ? By letting any Itemid being passed in a developer can hijack a route. Connecting a component to any random Itemid. Shouldn't that be prevented ?

[Hackwar]

This is necessary for the menu system to work. The menu module hands in "index.php?Itemid=XX" and this is sent through preprocess. If we don't allow Itemids to be set from the outside, we will get an issue here. So I've allowed that.

[johanjanssens]

Oki.

[johanjanssens]

@Hackwar As commented before. If the you need dummy methods here you can ask yourself if you really need those methods in the interface at all ?

[Hackwar]

My first implementation did not have an interface but instead you could simply hand in callbacks for rules. You also had to manually assign them to parse and build rules. That was before I introduced preprocess and before I expected the rule to be an instantiated object with the router handed in through the constructor. That said, I decided against the ultra-flexible solution, since I think it is more error-prone for third party developers and choose this interface. It requires less methods to register rules and less code to store and execute them and at the same time gives devs a construct to work from.

[johanjanssens]

Not following you here. Does that mean you agree in getting it out of the interface or not ?

[Hackwar]

This means that I think the interface is good the way it is.

[johanjanssens]

@Hackwar As commented before. If the you need dummy methods here you can ask yourself if you really need those methods in the interface at all ?

[Hackwar]

See my previous comment. 😄

[johanjanssens]

@Hackwar Since you are using the result of buildLookup() in this code block I would make buildLookup() return the lookup array. It can still cache it but it makes sense it returns it for use in the code block here.

[Hackwar]

This might sound stupid, but I wanted to optimize away a function-call here. I also choose the direct access of the lookup property in the code further down in the hopes that it saves a bit of memory and time instead of copying a pointer each time into a new variable in the methods scope etc. Yes, it might be a bit over-optimized, but I would stick to it.

However I see a bug in there, that the $language is not correctly set if the lookup is already created and the query language parameter is set. Will have to split that into 2 ifs.

[johanjanssens]

I would choose code readability over the few microseconds you might be saving here. Especially since you are already caching.

[johanjanssens]

@Hackwar Not sure about the proposed function name here. getMenuItemMap() might be a better name to reflect what this method is doing. I would also not make it return void but return the result instead. The result could be filtered by the language passed in through the method parameter.

[Hackwar]

Its the name that we used so far in the *HelperRoute classes for this. I simply choose it for the sake of familiarity with those methods.

[johanjanssens]

Since you are adding it new here and we are refactoring and removing the HelperRoute classes anyway, I would consider renaming it to benefit a clearer API.

[johanjanssens]

@Hackwar Getting the active menu item is a common operation in a router. Could consider adding a getActiveMenuItem() method to return this.

[Hackwar]

Sorry, but I would call that over-engineered code. The method would simply contain this one line and that is it and I don't see any benefit in that.

[johanjanssens]

I don't see why that would be over engineering. This is the L in SOLID, or the Liskov substitution principle and Design by Contract Those are well established programming principles.

By not exposing the getter you are relying on implementation instead of on an interface. Having a getActiveMenuItem() or getActiveMenu() as a getter creates a declarative API and make the code more easily extendable. It also better communicates the intention of the API by having the method as part of it.

I would still reconsider this and try to stick to SOLID as much as possible when creating new API's.

[johanjanssens]

@Hackwar Getting the default menu item is a common operation in a router. Could consider adding a getDefaultMenuItem() method to return this.

[Hackwar]

See my above note.

[johanjanssens]

See my note. Please consider it.

[johanjanssens]

@Hackwar Does this need to be accessible from object scope ? If not might consider making it private to prevent developers for using it directly ?

[Hackwar]

In general, rules should not be extended upon. They are self-contained pieces of code. But if someone really wants to, he/she should be able to mess around here. But since its not accessible from the component router, I would say that it is okay the way it is.

[johanjanssens]

Oki, you could still consider making it private for now. If someone needs to access this is could be made protected easily. Having it private gives you less to worry about in case the code needs to be refactored later.

[johanjanssens]

@Hackwar Did a first pass of the proposed code and added inline comments. I like the simplicity that is being proposed.

[weeblr-dev]

Hi Hannes,

How can 3rd party extensions disable/bypass those rules that could be added by components, or even if they make their way int Joomla core pre-4.0? or at least are you storing the original request somewhere so that we can revert any change made by those rules, as discussed in #5264?

"By letting any Itemid being passed in a developer can hijack a route. Connecting a component to any random Itemid. Shouldn't that be prevented ? ": Not random, but manually selected by user - as allowed by most SEF extensions, yes, absolutely.

Cheers

[Hackwar]

I guess JComponentRouterAdvanced will get a "removeRule()" method, that takes a rule that you can first find with a "getRules()" method and remove that from the rules to process again. Remember that you will have the buildpreprocess() step, where you can attach yourself already to, to for example add your stuff to the query.

[weeblr-dev]

This is not about attaching things to the query. This is about being able to undo things that other rules have attached, or any change they might have done to the original query. In other words not being trapped again in the problems the language filter plugins rules have created (not by themselves, but by being set in stone and unmodifiable)
getRules() and removeRules() sound good, as long as we have an event we can use to be reasonably sure all rules have been attached (so we can also be sure to remove them all). Too bad there isn't an onBeforeRoute...
I guess even if we use onAfterInitialise, we can rely on the plugins ordering so we should be good in most cases.

[Hackwar]

For the time being, I would add all rules in the component routers constructors, so when you cycle through all components and then use JRouterSite::getComponentRouter() and do your own stuff by adding/removing rules again in onAfterInitialise, you would be good. Since I would like to have more than one set of component rules, I could also see us having a -1 option that disables all the rule-adding in the constructor and you can do your magic.

Regarding the language filter plugin: I hope that it is a lot saner now when #5140 is merged. I can't really think of anything else that you could want in that regard...

[weeblr-dev]

Hi Hannes,
Let me clear that up first: I have no problem with the language filter rules, how they were working or whatever. The only issue was that we couldn't bypass them, or even know what the actual original request was and what the language filter rules had done to it. The same would apply to any extension adding rules, whether for parsing or building.
It was a bit more difficult with the language filter because its parse rule is always executed first, regardless of the actual system plugins ordering set by user or otherwise.

As for adding/removing rules on onAfterInitialise, I can request users to be sure my system plugin is the last one in order (and I can check that periodically) and thus be sure to remove all rules that may have been added by other extensions. An onBeforeRoute event would be more secure, but maybe not worth the added perf cost I guess. I'll make sure to do some trials in due time.

[johanjanssens]

@Hackwar About setName/setViewName() I missed those changes. Looking much better indeed API wise.

About JComponentRouterViewconfiguration vs JComponentRouterView. I understand, still not 100% happy with JComponentRouterViewconfiguration, any alternatives ? JComponentRouterConfig maybe, or JComponentRouterContext ?

[johanjanssens]

@Hackwar Oki, fair comments. Additional feedback :

• I still don't feel category handling should be in the this router. It would make more sense to me that this router is part of the categories component. It could be an abstract router one can extend from. By the chosen implementation you are tightly coupling categorie handling with routing.
• I would consider renaming JComponentRouterAdvanced to JComponentRouterView. Advanced isn't a very concrete name. This router deals specifically with component routing based on registering views. Would make sense the name reflect this, this also matches with the JComponentRouterViewconfigurationObject.

[Hackwar]

I've updated this PR to work with the changed JComponentRouterView class. Please test.

[dgrammatiko]

@Hackwar what shall we look for the output urls? just B/C or something more/else?

[Hackwar]

simply B/C. This should not change the URLs.

[Hackwar]

I've combined the changes from this and all other routing related PRs into a new PR: #7615 Please review and comment in the new PR. I'm closing this one, so that we can focuse on the new PR.