is a hot topic in Drupal community nowadays, it offers a lot of perks and it promises easy life for designers, clients and finally for developers. Being modern and innovative our team surely couldn’t pass by so we watched and read several articles about and full of excitement brought it to the upcoming project. One thing I noted though was that most part of the presenters had significant knowledge of Drupal which wasn’t my case but I didn’t pay attention that time. Pattern Lab There are 3 reasons we liked Pattern Lab for and I will go through them sharing what we found out and which you should pay attention on while adopting the technology.: Component based approach Decoupling frontend and backend so frontend can work without knowing the guts of Drupal Nice pattern library playground which can be shown to the customer/designer for early review 1. Component based approach With rising of frontend frameworks like React, Angular 2+, Polymer and many others it is hard to imaging non- nowadays which in short means that every component has its own scope for data, view and controller logic, which are normally presented with JS, CSS and JSON or YML, meaning changes inside one component won’t affect styles and internal logic of others. component based front end architecture So the normal component looks like this: Pattern Lab recommends to group assets into folders based on and provides a great support for component’s isolated dummy data giving us freedom to choose our own tools to handle JS and CSS scope which is a clever move in the sense that they cannot predict the preferred stack we normally use for that. Atomic design methodology : there is no much of complications about HTML scope so we just create own template for each component and then use it wherever we want through and twig directives passing appropriate parameter values. HTML twig include embed we can choose JSON or YAML format for components dummy data. Both are great and there are easy to quickly migrate from one to another though we picked YAML as it looks cleaner: Component Data: ways JSON vs YAML example These files are used solely to render components in the Pattern Lab UI and never appears on production. We can set multiple instances of dummy data for each component by simply altering the file name postfix separated with the tilde symbol which makes it super useful for testing and demonstrating different states of the component. Data file structure Example of different component states There is a global data file which is accessible throughout the tree of components so it is good idea to put for example global menu items or footer links there. Global data file is normally accessible by this location: . pattern-lab/source/_data/data.yml : The only data that is used to render a component is its own data and global data. If we include or embed component_1 inside component_2 we have to put data for component_1 into the data file of component_2. If you want to avoid that manual work check out this plugin: . Caution Data Inheritance Plugin : we used SCSS + SMACSS + BEM combination which gave us a way to isolate CSS through class naming convention. I won’t go into details here but you can take a look on some to achieve this. I’m also looking forward into for future projects. CSS SCSS tricks CSS Modules : is the most complicated part and breaks into several tasks. JS : Drupal 8 by default provide a very cool way to attach component’s CSS and JS to the page by introducing a which allows to specify different bundles in Drupal config and then include only those of them into the page which are really required. A library definition can look like this: Module bundler library concept And then has to be attached to the template by any of the methods described in documentation . here The problem can rise if from our example has its own dependency inside. It’s not a good idea just to put this dependency on the same level in config file cause in this case we have to copy it over everywhere. And if there are several levels of dependencies things become very confusing. accordion.js To solve this we used good old , and Webpack can also be an option. To make it work we just module inside our JS file and let Browserify handle it for us through a task. That’s how our component javascript file begins: Browserify require gulp overlay Another issue is that Pattern Lab knows nothing about the Drupal libraries concept and if we want our components to work inside its sandbox we have to add all same libraries into the file to make sure our JS is accessible on all pages inside the testing environment. pattern-lab/source/_meta/_01-foot.twig To simplify things in the beginning we just created one big JS bundle and attached it both to Drupal and Pattern Lab. Luckily we were able to keep the bundle relatively small and there were no much room to split JS between pages so our temporary solution became permanent :) : Once we have all components isolated we have to define a way how they communicate to each other. Component interaction Imagine we have a header component and a sidebar menu which slides-in any time button is pressed in the header. We could do the logic right inside the header JS(inside a click event handler) but as soon as we strived to a architecture we decided to go with a simple pattern in place and choose . It’s a pretty popular one and I some of its aspects before. loosely coupled mediator Redux covered One issue to not forget is that Redux by default calls all subscribers which we don’t want to happen cause we don’t have Virtual DOM and clever change detection mechanism here like React has, so we used an extension called and wrapped our method in the way that only required is invoked: store [redux-watch](https://github.com/jprichardson/redux-watch) subscribe reducer If terminology sounds confusing may be helpful. Redux documentation : If you never worked in Drupal projects you have to make yourself familiar with . In short in Drupal world we cannot rely on any document load events because any time Drupal through AJAX can replace any part of HTML with the fresh version of it and the only way we know about that is through method call. Drupal behaviors Drupal Behavior concept attachBehaviors So rule of thumb here: Always wrap your JS code with object Drupal.behaviors.yourName Behavior example Though Pattern Lab knows nothing about and we have to manually attach from Drupal core to all of our Pattern Lab pages inside file: behaviors drupal.js pattern-lab/source/_meta/_01-foot.twig Code for attached drupal.js Together with . This is already included in Emulsify Drupal theme which I will cover later so probably you just need to uncomment appropriate lines of code. ready.js Taking everything above is done and working seems we are good to go. But wait! 2. Decoupling One of the important aspects of Drupal + Pattern Lab combination is decoupling frontend work from backend meaning that those two teams can work almost independently by having clear separation defined by list of components and their parameters. And here tricky things begin. Decoupling is achieved by which gives a way to put all frontend templates in one place and then reference them from Drupal templates folder. twig namespaces module Still sounds good overall. : So let’s start with the forms. If you think you can make an input component and then in a Pattern Lab template it inside a form like this : Forms include you are wrong. The way Drupal handles it is first it renders separately each input component as a and then provide this rendered HTML as a string parameter to the . First time we found that out, we created an clause where for Pattern Lab we used and for Drupal we used rendered field . We created a global parameter named in file to have a way to distinguish if we are inside Pattern Lab or not. field form if include patternLab pattern-lab/source/_data/data.yml Example of incorrect code Don’t do this. First you cannot be sure there is no variable in Drupal and second there is a cleaner way to do the same which allows to have single version of file by moving Pattern Lab data to the place where it is supposed to be, to the YAML file: patternLab twig Example of correct code — twig Example of correct code — yml This is achievable thanks to by (very cool guy!, follow him if you are into Drupal front end). Data Transform Plugin aleksip : My first implementation of input looked like this: Attribute object Input — example of incorrect code Guess what? This is wrong. Drupal uses object for the forms and form controls to set and manipulate their HTML attributes. Attribute Learn about object and best practices how to use it Attribute here So the correct way is something like this: Input — example of correct code Luckily to make it work in Pattern Lab(thanks again to ) we can emulate attributes object inside a data file: Data Transform Plugin There is a cleaner way to handle attributes in Pattern Lab. Please check out the superb response from Evan Willhite, maintainer of Emulsify . Update 19.01.2018: here But Don’t use method inside Pattern Lab. It is . You should only use it in the Drupal templates folder. create_attribute() not supported : Drupal allows to quickly build a web application thanks to huge amount of contributed modules. Modules I am not sure why(may be some modules are not fully migrated to Drupal 8 or it is simply difficult to separate a view for them) but there are cases where you have to deal with whatever HTML you get from the server if you want to keep your fast development pace fast. One of the examples is a results. If you prepared a template for that you can throw it away. The only way you can style it is overriding CSS for that HTML which is already provided by the module. search Define with your team all modules to be used in the project in advance Forms, validation messages, , are good candidates for that. There was a case where I had to ask Drupal team to add a class to the element so I can add a padding in the end. Like it or not we have to deal with it. shariff sitemap Sometimes a module may be picked based on the underlying JS technology. Very popular for example uses inside so be ready to learn it on the way to debug your application.. or ask team to consider alternative one. Simple hierarchical select Backbonejs : Separate attention to module cause there are high chances it will be used in the application. Responsive images Drupal Responsive Images Be ready to receive from the server the whole rendered <picture> element instead of image path in your templates. : Not very Drupal-specific but remember about translations in your twigs. Discuss with the team which of those you’re going to use: Translations or string | t {% trans %} string {% endtrans %} and don’t forget about translation context if it is required though it can be fixed later with replace-all IDE functionality. : It is forbidden to write about Drupal debugging in the chapter dedicated to decoupling frontend with backend but Debug Drupal learn about and kint locating of Drupal templates We front end developers may not use these methods ourselves but at least we should know they exist and ask Drupal team to help with debugging when needed. : Drupal is a big open-source community meaning many things are already in place and done by some clever guys. To avoid reinventing the wheel it is good idea to start with the Drupal theme which already includes Pattern Lab. The most popular are: Themes — Particle — . Emulsify We started with Emulsify and I very appreciate the way they organized the tasks and but be careful as they use by default which doesn’t include important Drupal plugins namely: gulp documentation Pattern Lab Standard Edition for Twig — which allows to use Drupal filters and functions in Pattern Lab(say filter) Drupal Twig Components plugin | t and already mentioned above — which makes life much much easier( object, inside YML files, etc.) Data Transform plugin Attributes include Particle theme at the same time uses which includes both mentioned plugins by default and some useful methods like . Pattern Lab Twig Standard Edition for Drupal [npm run new](https://weknowinc.com/blog/drupal-theming-using-pattern-lab?utm_source=drupal-newsletter&utm_medium=email&utm_campaign=drupal-newsletter-20170104) Choose the correct Pattern Lab edition. If you still prefer the way everything organized in Emulsify theme just update file in it to pick the right edition. [pattern_lab.sh](https://github.com/fourkitchens/emulsify/blob/develop/scripts/pattern_lab.sh) 3. Pattern Lab UI Pattern Lab UI is good and easy to use. It allows to view a specific component, group of components or search one if you are not sure how to access it from the menu. One thing you probably should remember is that all your controls are tested inside an iframe If issues or special case arises(print page feature, for example) there is a way to test the component in a separate window outside of iframe: Menu to open component in a separate window Pattern Lab UI has a lot of settings but I didn’t find any good documentation for them. Please share in comments if you know one. Who to follow There are couple of blogs/repos I would suggest to follow to get some insights: _The personal website of Aleksi Peebles, a professional web developer since 1996 and a Drupal developer since 2007._www.aleksip.net aleksip.net _particle - A starting place for using the prototyping tool, Pattern Lab, in tandem with a Drupal theme. Can be used…_github.com phase2/particle _Components are the reusable chunks of web sites. They can be small (inputs, labels, buttons), medium (header, footer…_emulsify.info Emulsify // Pattern Lab + Drupal 8 Emulsify theme maintainer’s Evan Willhite blog: _Evan Willhite is a senior frontend engineer at Four Kitchens with who thrives on creating delightful digital…_www.fourkitchens.com Evan Willhite, Senior Frontend Engineer at Four Kitchens _Edit description_drupaltwig-slack.herokuapp.com Join Drupaltwig on Slack! _Willkommen im Blog der Internetagentur BUZZWOO! Hier finden Sie Artikel zu folgenden Themen: Drupal ✓ Wordpress …_www.buzzwoo.de Blog & Digitale News | BUZZWOO! And other resources suggested in the responses below( ). here Conclusion Pattern Lab indeed is a very nice way to organize and present front end template library and I don’t know any good alternatives for achieving that at the moment taking it is not a headless Drupal project. Projects like Particle and Emulsify make a strong move towards decoupling the front end and back end work though it is naive to think that having a prior Drupal experience is not a requirement anymore to write high quality front end code in such projects. Knowing how Drupal theming, forms and other popular modules work is still indispensable in my opinion. Have fun with coding and please let me know about your experience in the comments.
