"There's a module for that."
You've probably heard this before. Many times you can find a module that provides the functionality you need — or at least pretty close to what you need. Drupal's contributed module projects number in the thousands, but what if there isn't a module for your use case? You just might need to build a module for that.
In this series, you will learn about the tools and resources available to Drupal developers, including where to find documentation and what APIs are available to you, both on drupal.org and api.drupal.org. We'll take a look at the Devel module and learn how to use it to inspect the variables, objects, arrays and other things at work under the hood of Drupal 7.
You'll build several different modules that explore and interact with Drupal's various systems and API, including:
- Form API
- Menu system
- Hooks
- Render API
- Theme system
- Database API
Over the course of this series you'll be able to:
- Describe the anatomy of a module
- Implement common hooks
- Write more secure code
- Interact with Drupal's menu system
- Create and alter forms
- Peform CRUD operations on a database
This series starts with the basics and moves you step-by-step to more advanced concepts. Even if you are quite comfortable with PHP but are struggling to understand how to appropriately interact with Drupal 7's API, the lessons in this series can help you develop "The Drupal Way."
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.
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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.
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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.
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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
This chapter gives an introduction to how you work with Drupal's renderable, form arrays by adding an image button to the search form. It also walks through the process of adding the necessary classes to a form element so that the image button is properly aligned. The Forms API reference document is a pretty essential reference document for creating and editing forms in Drupal.
Although we use the function dsm() in this video, this should probably be dpm() as that's the preferred function name. The functions dsm() and dpm() are identical.
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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.
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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.
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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.
In this video we will look at how to add CSS and JavaScript to our site using drupal_add_css() and drupal_add_js(). We will also show using these functions to conditionally add the CSS and JavaScript, within our page preprocess function.
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In this video we'll see how we can create our own template suggestions. We'll do this in our node preprocess function to create a new node template that will be used depending on the day of the week.
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In this video we will look at overriding a theme function instead of working with the template files. We will be modifying the breadcrumb using theme_breadcrumb(). to do this we'll use the Theme Developer module to help us find what we're looking for, and then we'll walk through how to override.
Additional resources
Theme Developer module (Drupal.org)
960 Robots
In this video we will see how we can create our own preprocess function for a theme function (not just templates). We're going to use this to display the user's full name on the site wherever the the username would normally appear. We start by creating a full name field, and then show how to get this working on our site.
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In this video we cover a new Drupal 7 feature which lets us create suggestions for theme functions, in addition to suggestions for templates. We'll use this to modify the tags displaying on a node in our site.
Notes:
In the example: $item['#options]['attributes'] += $variables['item_attributes_array'][$delta]; += is a shortcut for array_merge. So it is ensuring the contents of $variables['item_attributes_array'][$delta] are included in $item['#options]['attributes'] so that any class, rdf info or other html attributes are appropriate applied to the tag links. It's possible for any number of modules to set HTML attributes on the tags field in the theme we need to make sure that they get printed out appropriately.
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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.
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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.
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In this video we introduce the template.php file and create our first preprocess function. We explain what the preprocess hooks are and how to name the function properly, then we show a list of existing variables, and how to modify one of those existing variables.
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PHP for Themers
FreeBefore we dive into advanced theming we are going to review the basic PHP you will need to use. This is a short review of PHP, including topics like data structures (arrays and objects), conditionals and operators, loops, and functions.
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In this series, we talk about template.php, the file where all your functions live. We’ll also discuss preprocess functions and overriding theming functions. You’ll learn how to create new variables and override existing ones using template.php. With these tools you can allow your theme to have complete control of outputted HTML.
In this video you’ll learn when to use a tpl.php file or your template.php file, and we’ll look at differences between them. We’ll also review the three main steps of theming.
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