A Gentle Introduction
Addison Berry, Lullabot
DrupalCon, Washington, DC 2009

A lot of people get a bit overwhelmed by Drupal coding.
Sometimes that leads to running away or hacking.

Systems, Frameworks
and APIs, Oh My!
API = set of functions that accomplish programming tasks - can be used “publicly”
Framework = basic app skeleton that solves common needs in a standardized way
CMS = features that help people build sites and manage content
Advantages: takes care of nasty, tedious stu; auth., security, etc. and its Open Source :)

Systems, Frameworks
and APIs, Oh My!
Content Management System
built on the
API = set of functions that accomplish programming tasks - can be used “publicly”
Framework = basic app skeleton that solves common needs in a standardized way
CMS = features that help people build sites and manage content
Advantages: takes care of nasty, tedious stu; auth., security, etc. and its Open Source :)

Systems, Frameworks
and APIs, Oh My!
Content Management System
built on the
Framework,
which uses the
API = set of functions that accomplish programming tasks - can be used “publicly”
Framework = basic app skeleton that solves common needs in a standardized way
CMS = features that help people build sites and manage content
Advantages: takes care of nasty, tedious stu; auth., security, etc. and its Open Source :)

Systems, Frameworks
and APIs, Oh My!
Content Management System
built on the
Framework,
which uses the
APIs
(Application Programming
Interface)
API = set of functions that accomplish programming tasks - can be used “publicly”
Framework = basic app skeleton that solves common needs in a standardized way
CMS = features that help people build sites and manage content
Advantages: takes care of nasty, tedious stu; auth., security, etc. and its Open Source :)

What is where?
CMS > framework > apis
Core modules and themes use the framework like everyone else.
Everyone should actually look at the files.
Includes folder holds the magic.

What is where?
CMS > framework > apis
Core modules and themes use the framework like everyone else.
Everyone should actually look at the files.
Includes folder holds the magic.

What is where?
base_path()
format_date()
l()
t()
url()
CMS > framework > apis
Core modules and themes use the framework like everyone else.
Everyone should actually look at the files.
Includes folder holds the magic.

Hooks
‣ Naming convention
‣ hook_* where hook is replaced
by your module name
‣ Lets modules add their own stuff
to Drupal’s workflow

A hook example
Hey modules! I’m
gonna display the
permissions page, you
have anything you
want me to add?
Naming convention for functions that lets modules jump in to the Drupal workflow

hook_perm
Each module can respond by saying they have something.
If they don’t have anything, they just don’t use the hook.

blog_perm
I do!
blog
Each module can respond by saying they have something.
If they don’t have anything, they just don’t use the hook.

block_perm
I do!
blog
block
me too
Each module can respond by saying they have something.
If they don’t have anything, they just don’t use the hook.

hook_perm
I do!
blog
blogapi
block I don’t
me too
Each module can respond by saying they have something.
If they don’t have anything, they just don’t use the hook.

Voila!
This is the display that gets made from hook_perm

The Train Analogy
• The Node Train leaves the station with node/12 hitched
It goes to the hook_nodeapi stop
Attaches the taxonomy and comment cars
Gets to the Theme depot

The Train Analogy
• The Node Train leaves the station with node/12 hitched
It goes to the hook_nodeapi stop
Attaches the taxonomy and comment cars
Gets to the Theme depot

The Train Analogy
• The Node Train leaves the station with node/12 hitched
It goes to the hook_nodeapi stop
Attaches the taxonomy and comment cars
Gets to the Theme depot

The Train Analogy
• The Node Train leaves the station with node/12 hitched
It goes to the hook_nodeapi stop
Attaches the taxonomy and comment cars
Gets to the Theme depot

Some major players
Menu
Form
Database
Theme

output: HTML, RSS
actions like: forwarding, login/logout
every internal link on a Drupal site is controlled by the menu system

Menu
๏menu.inc != menu.module
๏maps URLs to functions
๏functions can display output
and initiate actions
output: HTML, RSS
actions like: forwarding, login/logout
every internal link on a Drupal site is controlled by the menu system

give it an array and it will give you the form
not just for devs. themers can control form output

give it an array and it will give you the form
not just for devs. themers can control form output

FAPI
• form.inc
• handles the form, validation
and submission
give it an array and it will give you the form
not just for devs. themers can control form output

dbs are not standardized for creation (schema)
built in security

Database
• database.inc (and
database*.inc)
• schema creation
• abstracted to work with
multiple databases
dbs are not standardized for creation (schema)
built in security

output is put through the theme system
many core theme elements are found in tpl files in the modules

Theme layer
✦theme.inc
✦system module has default tpls
block, box, page
✦
✦ other tpls are in the module folder
output is put through the theme system
many core theme elements are found in tpl files in the modules

Theme’s rule
they get a last crack at all output so the themer can change whatever they need
a function named mytheme_function_name will trump core and modules

✴Module output uses theme()
✴Order of priority:
✴ theme_function_name()
✴ phptemplate_function_name()
✴ mytheme_function_name()
Theme’s rule
they get a last crack at all output so the themer can change whatever they need
a function named mytheme_function_name will trump core and modules

Resources
Developer/Theme handbooks
Drupal source/api.drupal.org
Dev/Theme mailing lists (drupal.com/mailing-lists)
IRC: #drupal (#drupal-dev) #drupal-themes
Issue queues
Paper books: http://drupal.org/books