YAML, which stands for YAML Ain't Markup Language, is a human-readable data serialization format that's been widely adopted in a variety of use cases in Drupal. Anyone wanting to write modules, or themes, for Drupal will need to understand YAML syntax. Even site builders are likely to encounter YAML at least in passing as YAML is the data-serialization format of choice for Drupal's configuration management system. Good thing it's pretty easy to learn even with the most basic of programming backgrounds.

This tutorial will look at the YAML data format and provide examples of how to write and read YAML. Starting with an introduction to the language's syntax and some of the strengths of YAML. Then looking at the difference between scalar data types like strings and integers, and collection data types like lists and associative arrays.

Since YAML in the Drupal world is read into PHP and ultimately becomes a PHP data structure that we can use in our own code we'll also look at how the YAML we write in a .yml file is represented in PHP data types. To do this we'll use the YAML Sandbox module that provides a handy textarea into which we can type YAML and have it parsed into PHP data structures.

Learning objectives

• Explain what YAML is and its strengths as a data serialization format
• Create scalar key/value pairs in YAML
• Create lists, and associative arrays using YAML collections
• Understand how the YAML you write is represented in PHP

Tips

• In Drupal, use the .yml extension and not .yaml
• Ensure your code editing application is configured to use spaces (preferably 2 spaces, as per Drupal coding standards), not the tab character when the TAB key is pressed. If you have tab characters in a YAML file within a Drupal environment, a fatal PHP error will be thrown and you'll see a White Screen of Death (WSOD).
• Copy and paste from an existing YAML file to ensure the formatting is correct, and edit from there.

Additional resources

• http://www.yaml.org
• YAML Sandbox module
• Find other tutorials and external resources related to YAML on our YAML topic page (Drupalize.Me)

Some of the content that's been added to our case study site isn't responding ideally as the viewport size increases and decreases. We have an HTML table that is a bit too flexible, making the columns too narrow for the text inside them to be very readable. The images in our slideshow are presenting us with a problem when the screen size gets too big: the images are scaling up and losing their quality in the process. To address these miscellaneous problems, we'll change how our content is placed, find some new breakpoints, and add new media queries for our grid_6 regions. We'll also learn some CSS tricks that will transform our table data into lists, making it more legible and sensibly presented on smaller screens.

Additional resources

https://github.com/DrupalizeMe/demo-rwd-7x (checkout branch 14-cleaning-up)

As we design for mobile, we want to look critically at each component and what it's communicating or how it's adding value. Now that we've refactored our theme to be more mobile-friendly, some elements in our header appear redundant when viewed in a narrow, stacked content column. This is causing our header elements to fill up that important initial screen on mobile. We want to ensure that our valued mobile users get more content and fewer redundant header elements when the page first loads.

In this lesson, we'll identify a breakpoint where the header gets too cluttered with elements essentially communicating the same thing. Then we'll add a new set of media queries, creating styles that will present a more mobile-friendly first impression of our site.

Additional resources

https://github.com/DrupalizeMe/demo-rwd-7x (checkout branch 13-mobile-friendly-header)

In the original theme, the width, margin, and padding of the elements that make up the search component are set using pixels. Since the width is static, it's breaking out of the sidebar region when the screen size is small enough. 

In this lesson, we'll refactor the styles in the search form so that it flexes with its parent container, instead of breaking it. In working through this example, you'll learn the merits of keeping components flexible and respectful of their parent containers.

Additional resources

https://github.com/DrupalizeMe/demo-rwd-7x (checkout branch 12-search-form)

Our image gallery plugin has long been known to be barely navigable on a small screen. Let’s fix our images and replace our photo gallery plugin with a responsive image slider that will work on small to large screens. We'll swap out Views Slideshow in favor of FlexSlider in this lesson.

Additional resources

https://github.com/DrupalizeMe/demo-rwd-7x (checkout branch 11-flexslider)

So far, we've adapted our layout to be flexible and fluid using relative units like percentages and ems, instead of absolute ones, like pixels. The problem is that smaller devices will often use resolutions much greater than the actual size of the screen size or viewport. So while our relative sizing is technically working, it's not going to be terribly useful or make our content more readable and accessible until we add an important tag to the head of our html template file: the viewport meta tag.

By adding the viewport meta tag to the head of our html template file, we're letting the browser know that we want the viewport size to be the size of the device, not some huge resolution more suitable for a 17" monitor, for example. This is a small but critical step in implementing a responsive design. Without it, our hard work of converting to relative units just isn't going to pay off.

In this lesson, you'll learn how to add a viewport meta tag to the head of all html pages using a special Drupal template file that we'll create. Then we'll step back and admire the results using our mobile emulation tools.

Additional resources

https://github.com/DrupalizeMe/demo-rwd-7x (Checkout branch 06-viewport-meta)
Written tutorial based on this video