An asset library is a bundle of CSS and/or JavaScript files that work together to provide a style and functionality for a specific component. They are frequently used to isolate the functionality and styling of a specific component, like the tabs displayed at the top of each node, into a reusable library. If you want to include CSS and/or JavaScript in your Drupal theme or module you'll need to declare an asset library that tells Drupal about the existence, and location, of those files. And then attach that library to a page, or specific element, so that it gets loaded when needed.
In this tutorial we’ll:
- Define what an asset library is.
- Explain why asset libraries are used to include JavaScript and CSS files.
- Look at some example asset library definitions.
By the end of this tutorial you should be able to define what asset libraries are, and when you'll need to create one.
Preprocess functions allow Drupal themes to manipulate the variables that are used in Twig template files by using PHP functions to preprocess data before it is exposed to each template. All of the dynamic content available to theme developers within a Twig template file is exposed through a preprocess function. Understanding how preprocess functions work, and the role they play, is important for both module developers and theme developers.
In this tutorial we'll learn:
- What preprocess functions are and how they work
- The use case for preprocess functions
- The order of execution for preprocess functions
By the end of this tutorial you should be able to explain what preprocess functions are and the role they play in a Drupal theme.
Template files are responsible for the HTML markup of every page generated by Drupal. Any file ending with the .html.twig extension is a template file. These files are composed of standard HTML markup as well as tokens used by the Twig template engine to represent dynamic content that will be substituted into the HTML markup when the template is used. As a theme developer, you'll work with this a lot.
In this tutorial we’re going to learn about:
- What template files are, and how they fit into the big picture of creating a theme
- How template files are used in order to allow theme developers to modify the HTML markup output by Drupal
- Naming conventions for, and specificity of, template files
What Is a Theme?
FreeThemes are the part of Drupal that you, and anyone else visiting your Drupal powered application, see when they view any page in their browser. You can think of a theme as a layer, kind of like a screen, that exists between your Drupal content and the users of your site. Whenever a page is requested Drupal does the work of assembling the content to display into structured data which is then handed off to the presentation layer to determine how to visually represent the data provided.
Drupal themes are created by front-end developer. Frequently referred to as themers, or theme developers. Themes consist of standard web assets like CSS, JavaScript, and images, combined with Drupal-specific templates for generating HTML markup, and YAML files for telling Drupal about the file and features that make up each individual theme.
In this tutorial we'll:
- Explain what a Drupal theme is.
- Explain the role of a Drupal themer in the process of building a Drupal site.
- Get a high level overview of the types of files/code that themes are made of.
By the end of this tutorial you should be able to explain what a Drupal theme is, and the kind of work a Drupal theme developer will be expected to do.
Maybe you've heard of anonymous closures but you're not quite sure how they apply in Drupal, or why using them is considered a best-practice. Anonymous closures allow you to avoid accidentally clashing with anything in the global scope, as well as to alias the jQuery object to the more commonly used $
. This is necessary because Drupal runs jQuery in no-conflict mode. This tutorial will look at the syntax used for placing your custom JavaScript code inside an anonymous closure, and why it's a good idea to do so.
In this tutorial we'll:
- Explain what a closure is (briefly), and what immediately invoked function expressions are
- Show how typically Drupal JavaScript gets wrapped in a closure
- Provide a copy/paste example you can use in your own code
By the end of this tutorial you should be able to explain what an anonymous closure is, and how to use one in your custom JavaScript for Drupal.
Like most output in Drupal, Views relies on Twig templates for a significant amount of its rendering. In this tutorial we'll identify where you can find the default Views templates within your file system, what the common templates are for, and how to name your templates so that they are applied to specific views.
By the end of this tutorial, you should be able to:
- Identify where to find default views templates
- Understand which templates apply to what part of a view
- Get a sense of the template suggestions and how to use them to limit where your custom templates are applied
- Identify a view's machine name
- Identify a display's machine name
- Identify a field's machine name
Now that we understand what templates are and how we can use them, let's override some templates! In this tutorial we'll copy the views wrapper template to our theme and override it so that we can customize the markup for the Baseball Players view. Then we'll modify the template so that our view's pager appears both above and below our table of players.
Customizing the available regions in your theme is one of the first things you'll do when creating your own themes. Doing so gives you complete control over where content is displayed on the page, and the markup involved. Adding regions to a theme is a two-step process that involves editing your theme's THEMENAME.info.yml file and updating your page.html.twig file.
In this tutorial we'll:
- Declare one or more new regions in our themes THEMENAME.info.yml file.
- Output the content of those regions in our theme via the page.html.twig file.
By the end of this tutorial you should be able to add or edit the regions a theme provides. Also, you'll ensure that blocks placed into regions are displayed by outputting the regions in the page template.
Contributed and custom themes can ship with a thumbnail screenshot that will be used to represent the theme when listing themes in the administration UI.
In this tutorial you'll learn how to:
- Prepare your site for the screenshot
- Create a screenshot of your theme
- Define a screenshot file for your theme in the THEMENAME.info.yml file
Preprocess functions are specially-named functions that can be used to add new variables to a Twig template file. They are commonly used by themes to add new variables based on custom PHP logic and simplify accessing the data contained in complex entity structures. For example: adding a variable to all node.html.twig template files that contains the combined content a couple of specific fields under a meaningful name like {{ call_to_action }}
. Modules use preprocess functions to expose the dynamic data they manage to Twig template files, or to alter data provided by another module based on custom logic.
In this tutorial we'll learn how to:
- Use PHP to perform some complex logic in our theme.
- Store the resulting calculation in a variable.
- Make that variable available to a Twig template file.
Example use cases for adding variables with preprocess functions include:
- Anytime calculating the value to output in a template requires logic more complex than an if/else statement.
- Anytime the desired value requires additional string manipulation beyond what can be easily accomplished using an existing Twig filter or function.
By the end of this tutorial you should be able to expose new variables to a Twig template file by defining a preprocess function in either a module or a theme.
Twig has a special syntax for accessing array keys and objects, also known in Twig as variable attributes. In this tutorial, we'll cover the period or dot (.
) operator to access a variable attribute, as well as subscript or square-bracket syntax, useful for when the key of the array contains special characters, like a dash (-
) or pound sign (#
). We'll also look at the logic Twig uses to find the matching attribute in an array or object.
Once you've defined an asset library you'll need to tell Drupal when you want to add the CSS and JavaScript that it includes to the page. Ideally you'll do so in a way that allows Drupal to only add the corresponding assets on pages where they are needed.
You can attach a library to all pages, a subset of pages, or to elements in a render array. This allows you to have some assets that are global, and others that get loaded on an as-needed basis. To attach a library you'll need to know both its name and prefix, and then use one of the techniques outlined below to let Drupal know when to include it.
In this tutorial, we'll look at attaching asset libraries:
- Globally, via your THEMENAME.info.yml file
- Conditionally, via a preprocess function using the
#attached
render array property - Inside of a Twig template file
By the end of this tutorial you should be able to attach asset libraries in various different ways depending on your use case.
It's probably not too surprising that a library called Backbone aims to provide structure to your front-end JavaScript code and applications. In this tutorial we'll take a look at how Backbone.js goes about achieving that goal, and how you can make use of it on your Drupal site. We'll first take a high-level look at the main components that make up the Backbone.js library. With that basic understanding in place we'll look at an example of how you might integrate Backbone.js into a Drupal site.
Drupal's Breakpoint module defines a "breakpoint" plugin type that modules or themes can implement via a breakpoints configuration file. So, in order to make their breakpoints discoverable, themes and modules define their breakpoints in a THEME-OR-MODULE.breakpoints.yml file located in the root of their directory.
In this tutorial, you'll learn about the structure of a breakpoints configuration file and why you would want to use one. We’ll cover the kinds of metadata you can include in a breakpoint file, including key, label, mediaQuery, weight, multipliers, and breakpoint group. Throughout, we'll look at some examples of breakpoint configuration files available in Drupal themes and modules.
By default, individual forms in Drupal are not output using Twig template files. It's possible to associate a form with a Twig template file by creating a new theme hook, and then referencing that theme hook from the $form
array that defines the form. Doing so allows theme developers to customize the layout of the elements in the form using HTML and CSS.
This is useful when you want to change the layout of the entire form. For example, putting the elements into 2 columns. If you want to change individual elements in the form, you can often do so by overriding element specific Twig template files.
In this tutorial, we'll:
- Learn how to create a new theme hook that can be used to theme an element in a render array.
- Associate the
$form
we want to theme with the new theme hook we created. - Create a Twig template file for the theme hook that will allow us to lay out the form elements using custom HTML.
By the end of this tutorial, you should be able to associate a Twig template file with any form in Drupal, so that you can customize its layout using HTML and CSS.
Converting an exisiting theme to Omega takes time and some planning, but Omega gives us plenty of options of moving things around the page all without touching a piece of code. When working with a grid layout we use Omega to set all of our content to span the proper columns all while moving our content from zone to zone so it is placed properly on the page. We will cover:
- Moving content from zone to zone
- Choosing proper zone column widths
- Splitting column amounts to create right and left columns
Once all of this is complete we are just a few steps away from getting into some CSS and really making our theme come together as an Omega sub-theme.
Additional notes:
If you want to touch code, you can edit the .info file as such (for the first part, moving branding zone):
settings[alpha_region_branding_zone] = 'header'
...
settings[alpha_region_branding_weight] = '3'
...
settings[alpha_region_header_first_weight] = '1'
...
settings[alpha_region_header_second_weight] = '2'
Responsive design is more than a just a buzzword these days but a standard practice of good web shops when building out a site. Omega provides a responsive design out of the box and gives lots of options to layout your content in the proper places and the ability to work with the break-points all with a User Interface. In this lesson we will cover:
- Omega responsive options
- Column settings for your grid layout
- Omega responsive layout settings
- Device viewports and media queries
We end the lesson getting our new sub-theme ready to handle our 960 robots theme and the 16 column setup we designed it with.
If you prefer working with code, instead of the web UI, you may configure your theme as follows to change your column settings from 12 grid columns to 16 in your theme's .info file:
Find and replace all the instances of:
_columns] = '12'
with:
_columns] = '16'
There may still be additional regions that also need to be set which weren't the full width. You can edit other regions as needed, such as:
_region_user_first_columns] = '8'
change to:
_region_user_first_columns] = '12'
Walks through the process of first adding the search block to the node template file, and then explains some of the best practices for incorporating JavaScript scripts within your theme. Walks through how to protect the dollar-sign variable, and how to use the Drupal behaviors instead of the document ready so that your JavaScript will fire not only on page loads, but also if there is any dynamic material being loaded on the page through asynchronous page loads. We'll show you how to select the jQuery selector to target the desired element, and how to conform to Drupal's best-practice coding standards when it comes to integrating JavaScript and jQuery into your theme. You can learn more about jQuery itself with the Introduction to jQuery Series.
To use Query in no conflict mode, because was not defined.
Add this line on the top: jQuery.noConflict(); more info here: http://api.jquery.com/jQuery.noConflict/
To improve how the search box looks, you need to modify the following:
currently : search-theme-form
modify to: search-block-form
and then in the property in line 321 to look like this:
/* Header quick search */
#header form#search-block-form {
top: -165px;
Additional resources
Shows how you can use the ajax framework in Drupal 7 to load additional content onto the page dynamically after clicking on a 'read more' link.
The sample code for this series is in the Downloads tab for the first video in this series: http://drupalize.me/videos/introduction-jquery-and-javascript-drupal#do…. If you're skipping around, and things aren't working, you may benefit from going back to the beginning and completing each of the videos in order.