This guest post was written by Ben Hosmer, a Drupal user new to module development as well as an active member of the Florida Drupal user community. He often blogs about Drupal related topics at radarearth.com

For the past five or six months, I've been itching to write a Drupal module. It seems to me to be the final step in attaining that Drupal nirvana, and you gain instant street cred as well at the monthly meet-ups. I've heard it also can up your certified to rock score too, since you get commits added to your history.

Thinking back to my early days learning Drupal, the mythical, magical, modules were those things you didn't mess with. You downloaded them, installed them, and usually they worked. The module developers were the big kids on the playground. The seniors in high school, so to speak. But, because of Drupal's awesome community, they weren't the bullies.

The CacheFlusher isn't my first module. I got my feet wet updating the Apture Module to Drupal 7, with some guidance from @ultimike (Mike Anello). Yeah, he is certifiied to rock a 7.

I learned a few things while I was updating the Apture Module, that made it a bit easier to write my own module from scratch.

What you need

First of all, you don't necessarily need to be a PHP guru to write a module. In fact, I am very far from it. You will need some basic, general understanding of programming flow though. I had dabbled in python before, and have been learning some PHP along the way too, but it definitely is not a pre-requisite. You just need a basic understanding of what code does.

You will need three things to write a module:

1. A Drupal Installation
2. A Text-Editor
3. An internet connection (For references to the API)

You can set up a development environment on your local computer using WAMP if you are running windows, or MAMP if you are on the MAC. Linux folks, you most likely already have everything you need. Just make sure you are running PHP5.

Check out these getting started guides to help you get WAMP or MAMP if you don't already:

MAMP: http://www.mamp.info/en/documentation/index.html

WAMP: http://www.wampserver.com/en/

For an even easier setup with no installation, go to webenabled.com and sign up for a free account, although transferring files back and forth for testing might become tedious.

There are numerous text-editors available. A lot are free. Your operating system probably includes one. TextWrangler is my personal favorite for the mac, but you really need to try different ones to decide which one you really like. Windows users can use Notepad++. Some offer syntax and code completion as well as a lot of other nifty features.

Let's get started

The Modules Directory

First, if you have installed any contributed modules before, and you have ever peeked inside your sites/all/modules directory, you will see that there are a bunch of other directories with names like “views”, “mollom” and “colorbox”. These folders contain the code for each contributed module installed on your site. You will also notice that the names generally coincide with the name of the module. This is important, as we will soon learn.

Open one of the folders and look inside. I will promise you that you will see at least two files there along with possibly a README. One has a .info extension and the other has a .module extension, preceded by the exact same name of the parent directory.

This is how Drupal keeps track of the contributed modules available when you visit admin/modules

If you plan on sharing your modules with the rest of the world, (really why wouldn't you), go set up git on drupal.org using the Git Instructions as your guide.

The .info File

After following the instructions, cd into your new module directory. You should see a .info file with your repository name already there. Drupal does this for you when you create your sandbox, and you just cloned it into your directory.

Open that .info file. This is kind of the table of contents for your module and contains some standard entries that every module should have.

What you will see is: name = yourmodulesname

This tells Drupal what the name of your module is. This is also where the information contained in the module overview page at admin/modules comes from.

We should add a few things before we are done here. Hit enter and start a new line.

Add description = a description about what your module does.

This creates the description for your module on the module overview page.

Our next entry will tell Drupal where to categorize our module. When you view the module overview page at admin/modules you will see some headings for subcategories like “Core”, “Services”, and “Taxonomy”. This helps to keep your modules organized.

Add a new line and type package = administration

The last entry we will need is important so that Drupal knows what version of Drupal this module was created for.

Add core = 7.x

This tells Drupal that your module is for Drupal 7.

If you plan on sharing your module, don't add a “version” entry. Drupal will automatically do this for you when it is packaged.

Make a new line, and add your final entry, files[] = yourmoudlename.module

This directs Drupal to your actual module code so that it can run.

Save your .info file.

What the .info File will Finally Look Like

Here is what the final version of the CacheFlusher module's .info file looks like:

name = CacheFlusher

description = Adds a quick way to flush your cache with a button on the admin toolbar.

package = "Administration"

core = 7.x

files[] = cacheflusher.module

If you start up your Drupal installation and go to admin/modules, you will see a new entry for your module on the module administration page. It won't actually do anything yet though.

The .module File

Next, you need to add your .module file. This is where all of the work gets done.

What are Drupal Modules?

Drupal modules are basically a series of functions, with a majority of them being function calls to Drupal functions. The documentation for every function available to Drupal can be found at api.drupal.org. This is your resource for finding out what each function does and how to use it.

As a newcomer, I found it to be lacking in examples. Sometimes it can be impossible to figure out what the function actually does. So, instead of complaining in a comment, I added some examples to the API entries.

 

After my frustration, I discovered the Examples Project that provides an excellent group of modules that do just what the project name implies--provide example modules for developers that give working code examples of what some of the popular functions actually do. It is an excellent resource and you should add it to your bookmarks toolbar because you will probably refer to it quite often.

 

You may find it very helpful to find a module that is very simple, and look through the code. If you are adding a menu entry for example, find a module that does the same thing and look through the .module file. 

 

Often you might find .inc files. These point to additional code that wasn't included in the .module file. These will be noted in the .module file though with a filename.inc. This references those additional files.

 

Another good resource is your Drupal installation itself. By browsing to the core modules folder found at /modules, you can search for the function you are looking for by using spotlight if you are using a mac, or search for windows or locate from your nix terminal.

 

This can often shed some light on the function or at least reveal what function to implement to perform a certain task.

Now that you have your .info file and your directory. You are ready to create your .module file and spin some code up.

View Your Module in Action

You can actually now got to your Modules page through your Drupal interface, and see the new entry for your module:

The second part of this article will go through the creation of your actual .module file.

Join Ryan Price, Mike Anello and special guest Matt Butcher - one of the co-authors of "Drupal 7 Module Development" as they discuss the book, the growing complexity of Drupal code, new modules, DrupalCon 2013 (Go Canada!), and their picks of the week!

Five Stories

1. Drupal 7 Module Development from Packt Publishing and Why Object-Oriented Programming is Bad for Drupal. Matt's personal blog is at http://technosophos.com
2. Fast Tracking Drupal Bug Fixes and http://drupal.org/node/1050616
3. Form Elements in Views (video) 
4. DrupalCon North America Straw Poll and selection committee info.
5. Aloha HTML5 WYSIWYG and Chx's blog post 

Picks of the Week

• Mike - The Art of Estimation by Seth Brown, Seth on the Drupal Voices podcast. 
• Ryan - Eva - Entity Views Attachment by Jeff Eaton
• Matt - Drupal 8 Configuration Initiative, DataTables: a jQuery plugin that makes tables pretty, http://schema.org (Manu Sporny's blog post about schema.org) , RDF/RDFa on Drupal.org, Google +1 button 

Sponsor

WebEnabled.com

Site of the Week

If you'd like your site highlighted, please submit it at http://DrupalEasy.com/siteoftheweek.

Follow us on twitter:

• @drupaleasy
• @andrewmriley
• @liberatr
• @ultimike
• @webenabled
• @technosophos

If you'd like to leave us a voicemail, call 321-441-3964. Please keep in mind that we might play your voicemail during one of our future podcasts. Feel free to call in with suggestions, rants, questions, or medicinal advice for Andrew. If you'd rather just send us an email, please use our contact page at http://DrupalEasy.com/contact

Drupal Rock Star Amitai (pronounced om-eee-tie - trust us, we checked) Burstein joins Ryan, Andrew, and Mike to talk about Organic Groups for Drupal 7, Acquia, Webchick, and mobile Drupal.

• @drupaleasy
• @andrewmriley
• @liberatr
• @ultimike
• @webenabled

Bonus: Find Waldo somewhere in this podcast notes (it might be linked to) and post in the comments where you found him. We don't have any prizes but perhaps we'll give the first person a shout out on the next podcast.

If you'd like to leave us a voicemail, call 321-441-3964. Please keep in mind that we might play your voicemail during one of our future podcasts. Feel free to call in with suggestions, rants, questions, or medicinal advice for Andrew. If you'd rather just send us an email, please use our contact page at http://DrupalEasy.com/contact

Hey, hey, the gang's all here with our brief DrupalCon Wrapup, Drupal 8 initiatives on the horizon, a brand new Views 3 inside and out, a better issue queue for Drupal.org and a look at how the Drupal.org Sandbox projects are going.

5 Stories

1. DrupalCon Chicago Wrapup - a few favorite sessions
   
   1. Mike - Drupal Commerce by Ryan Szrama
   2. Ryan - Render API in Drupal 7 by Franz Heinzmann
2. Drupal 8 Announcement & Configuration Management in Drupal 8 Lead Selected
3. Drupal.org Prairie Initiative (DX) and Leisa's Core Conversation from DrupalCon Chicago
4. The New Views 3 UI and Views 3 API are awesome
5. Drupal.org Sandbox Projects at One Month

DrupalEasy News

1. Peachpit Article by Mike - Interview with Tom Geller
2. DrupalCon Chicago video interviews on DrupalEasy.com

Thanks to WebEnabled Instant Development Platform for sponsoring this week's podcast. Create, develop, and deploy Drupal applications entirely on the Webenabled platform.

Picks of the Week

• Mike - Metal Maker sandbox project by Rubén Teijeiro and for the d20 warriors out there, D&D Character by Toby Hagler.
• Ryan - Media Pool by J. Ayen Green (credit to Drupal Radar for finding this one)
• Andrew - Drush 4 - see the blog post by Moshe

Site of the Week

http://drupaldistrowatch.com/

If you'd like your site highlighted, please submit it at http://DrupalEasy.com/siteoftheweek.

Follow us on twitter:

• @drupaleasy
• @andrewmriley
• @liberatr
• @ultimike
• @webenabled

If you'd like to leave us a voicemail, call 321-441-3964. Please keep in
mind that we might play your voicemail during one of our future
podcasts. Feel free to call in with suggestions, rants, questions, or
D&D challenges for Andrew. If you'd rather just send us an email,
please use our contact page at http://DrupalEasy.com/contact