This chapter describes how Drupal modules are able respond to specific events through the hook system. A couple of example hooks are implemented in order to see how this process works. This video builds on the demo module we created in the previous chapter.
This screencast shows “how you can use multiple-parameter Rules components in VBO and get the additional parameters as action configuration,” which translates to:
- If you have more than one parameter for a Rules component, you can still use it with VBO.
- Any additional parameters will be displayed as action configuration, meaning that the person executing the VBO gets to choose parameter value.
- Sadly, you can’t access data from the view item being actioned – you’ll have to stick with fixed input values. (If you want to use data from the processed item, you could actually do this inside the Rules component!) This is an issue being worked on.
- If you have complex parameters – such as taxonomy terms instead of just an integer – you can (mostly) use entity ID in the direct input mode.
- You can, by coding, change the form elements used for input. It is probably better to target the Rules data widget than doing a standard form_alter, but both will work.
- You could, for example, use this for changing comment settings on nodes, or adding selected tags to nodes. (Both examples shown in this screencast.) You could also use it for, say, sending customized messages or something. Or cloning existing nodes with changes specified in parameters.
- Bonus: If you add an entry to a multiple-value field in an entity, Rules won’t pick up that the entity has changed – make sure to add a “save entity” action in the rule.
Not mentioned in this screencast but still good to know:
- You can have Rules components without any parameters as well. No sweat.
- You can use Rules components without any parameters matching the View type too. In that case, you’ll have to specify all the parameters manually.
- If you have a component with several parameters matching the view type, the first one will be auto-populated by VBO – the rest you have to set manually.
Additional resources
Rules guide (Drupal.org)
This screencast shows how to start using Rules Scheduler. It does this by mimicking the Comment Closer module – closing the comments on articles two weeks after they are created. The screencast covers:
- Rules Scheduler needs components – you can only schedule prepared components
- Components can be scheduled as actions, for example from reaction rules
- The evaluation time for scheduled tasks is set with strtotime(), which means that you can use highly flexible expressions
- You can also use data selection, combined with offsets if you want to
- Every scheduled task should have a unique task ID, or it will replace existing tasks
- Scheduled tasks are displayed under the Schedule tab on the Rules admin pages
- You can delete tasks manually if you want to
- You can schedule tasks manually, without the need of reaction rules
- It is sometimes useful to execute rule components manually, to see that the scheduled tasks will work as expected
Additional resources
Rules guide (Drupal.org)
It is very time consuming and error prone to repeat "click steps" among multiple sandboxes, development and production in order to get your new image styles to appear. In this video, I will show you how to write code that turns your "custom" image style into a "default" image style so that you can use source control to update all of your site environments.
I am assuming you already know how to create image styles in the administrative interface. Familiarity with basic module development is helpful, but if you follow the techniques and patterns I demonstrate, you will successfully export your image styles into a new custom module.
This chapter explains hook_page_alter(), which is another alter hook new to Drupal 7 and to the theme layer. Each page rendered by Drupal is contained within an array where the theme is able to go in and rearrange, delete or duplicate specific page elements.
Additional resources
This chapter shows some general best practices for keeping your template.php file clean as well as making it easier for designers to work primarily with the template files when possible to avoid them having to make too many changes to template.php. Specifically, some HTML classes are removed from the ninesixtyrobots_comment_form() function in template.php and moved to the comment-form.tpl.php template file, which is specified as an option in the ninesixtyrobots_theme() function. The rendering logic is also removed from the theme function and into a preprocess function so that it can be passed in as a variable to the new template file.
Additional resources
The ability of having alter hooks within the theme layer starts to blur the line between the logic and presentation, and so there are a few things to be aware of when using hook_form_alter() from the theme layer. The biggest thing to know is that the form rendering process has already gone through the creation and validation preparation process at the module layer, and so you shouldn't be drastically changing the functionality of a form at the theme layer. This form alter hook at the theme layer is primarily for aesthetic clean-up, styling and additional design. This chapter gives some specific examples of things to watch out for.
Additional resources
There are four alter hooks that are now available to the theme layer in Drupal 7. This chapter walks through two of those hooks, hook_css_alter() and hook_js_alter(). These hooks allow the theme layer to reorder, delete or replace specific CSS or JavaScript files that are being loaded by Drupal core or other contributed modules.
Additional resources
In this video Joe Shindelar provides a quick overview of the minimum set of tools you'll need in order to get started with module development. Some kind of web server to host your development site on, an editor that allows you to edit PHP files (preferably one with syntax highlighting), a MySQL client, and Drush. Learn about how these essential tools fit in the module developers tool belt and then download and install a bare bones copy of Drupal to start tinkering with.
This lesson goes through the process of creating Theme Settings so that administrators of a theme are able to turn on and off specific features within the the theme, as well as specify other relevant settings.
Note: Twitter has recently shut down their v1 REST API so this lesson's site_slogan adjustment no longer works (it will always return no values because there is no API data found). The core concepts of how to create theme settings are still correct, you just won't be able to see the output from Twitter.
Additional resources
This chapter goes through the process of adding a specific form id to the theme registry with the hook_theme() function, which allows the creation of a new function that targets a specific form. Specifically in this chapter, comment_form is added to the theme registry so that we can create a ninesixtyrobots_comment_form() function in order to add a column to the comment form so that the name and subject fields are displayed side-by-side.
Additional resources
Provides an overview of what is covered in the Theming Basics series and gives a preview of what is yet to be covered within the Advanced Theming video.
Walks through the process of adding a screenshot to you theme so that it'll show up properly within the theme administration page, following the screenshot directions found on Drupal.org, and using the Skitch screenshot app (you can use whichever screenshot app you like).
Additional resources
Takes a tour through some of the more useful template variables, and more ways of determining the available variables by adding the following code to a page template:
Walks through the process of copying the default node.tpl.php file from the core node module into the theme, and then customizing the output specific to individual in order to match the design. See how to add specific variables, when to use conditional if statements and the best way to debug and iterate through this process.
Additional resources
In this chapter, we add some sidebar and footer regions to the page via the .info files, and printing those new regions out in our page template file, adding some blocks to help with testing. We also talk about Devel and Krumo, and how we can use those to find out everything that is available in out page array, using the dsm() function. While inspecting out page array, we point out the differences between elements and properties within renderable arrays.
Additional resources
We'll go a step further with our preprocess functions and look at working with node variables, and how to limit new variables to only specific content types.
Additional resources
This video walks through the process of replacing static content in the page.tpl.php file with dynamic variables. Joe talks about the html.tpl.php file as well as pointing some of the important variables that should be included within the theme.
Additional resources
This chapter covers some really handy browser extensions in the process of theming. For Firefox, there's the Web Developer Toolbar for turning off and on JavaScript, resizing the browser window to different sizes, and inspecting elements. It also has the capability to test changes to CSS files in a format that is easy to copy and paste into the source file. We also show off the basics of the popular Firebug extension, and the equivalent functionality that is now built in to webkit-based browsers such as Safari and Chrome.
Additional resources
Continuing on our work with preprocess functions, we look at how to add a new variable for our template files to use. We also see how to change the output based on whether the user is logged in or not, and how to add a variable to the t() function.