Drupal 7 Module Development

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Chapter 1 The database We have taken a brisk walk through a typical Drupal request, and we have learned a little about modules and libraries. However, what about the database? Unlike many architectures, for Drupal the database doesn't stand front and center. The database layer is not a module, nor do modules need to declare a specific relationship with the database. In fact, many Drupal modules do not ever interact directly with the database. Unlike Model-View-Controller (MVC) frameworks, Drupal does not require that modules follow an MVC pattern. For that reason, a module can exist, yet not have any database structures (models), a central controller, or even any usercentered theming (view). Instead of treating the database as a central architectural component, Drupal merely provides an API for working with the database. In Drupal, the database is just a place to store data. Need custom tables? Drupal provides a system for declaring them. Need to get data out of the database, or insert or update new data? Drupal provides functions and an OO library for doing so. However, if you don't need such features for your code, you needn't work with the database at all. In fact, in the next chapter we will write our first module without writing a single SQL query. Later in this book, we will see how to interact with the database using Drupal's robust database tools. More than just data The Drupal database does not store just application data (or content), but also configuration, caches, metadata (data about data), structural information, and sometimes even PHP code. While Drupal may not be database centric, it most certainly requires a database. During initialization, Drupal will connect to a database and retrieve certain configuration data. Later, as many of the core modules load, they too, contact the database to retrieve or update information. For most Drupal modules, the database is the location for data storage. [ 15 ]
Developing for Drupal 7 The theme system The final component from our initial architectural diagram is the theme system. Drupal separates the look-and-feel components of the system from the rest of Drupal, and provides a programmatic way for theming data. The system for handling this is collectively called the theme system. Some of the theme system resides in the Drupal core libraries. This part is responsible for initializing themes and locating what theme functions and templates should be applied under certain circumstances. However, the majority of the theme code resides in themes and modules. A theme is a structured bundle of code (like a module) that provides tools for transforming raw data into formatted output. Sites use at least one theme to apply a consistent and custom look-and-feel to all of the pages on the site. However, Not all theme code resides inside of a theme. One of the distinct advantages offered by Drupal is the capability to define default theming inside modules, and then provide mechanisms by which the theme layer can selectively override those themes. In other words, a module might declare a rough layout for a component, but Drupal provides the structure for a theme developer to later modify the theme (not the module) to re-layout that component in a different way. If this all sounds conceptually difficult, don't worry. Chapter 3 and Chapter 4 of this book are dedicated to working with the theming system. Now that we've had a quick architectural overview, let's change perspectives and quickly peruse the major subsystems offered by Drupal. Drupal's major subsystems In the previous section we took a birds-eye view of Drupal's architecture. Now we are going to refine our perspective a bit. We are going to walk through the major subsystems that Drupal 7 has to offer. Themes The theme subsystem was introduced above, and since Chapter 3 and Chapter 4 will cover it, we won't dwell too much on it here. However, there are a few details that should be mentioned at the outset. [ 16 ]
Page 1 and 2: www.allitebooks.com
Page 3 and 4: Drupal 7 Module Development Copyrig
Page 5 and 6: Foreword Drupal has its roots in th
Page 7 and 8: About the Authors Matt Butcher is a
Page 9 and 10: Larry Garfield is a Senior Architec
Page 11 and 12: John Albin Wilkins has been a web d
Page 13 and 14: Jojodae Ganesh Sivaji has been invo
Page 15 and 16: Why Subscribe? • Fully searchable
Page 17 and 18: Table of Contents Tools for develop
Page 19 and 20: Table of Contents A shortcut for sy
Page 21 and 22: Table of Contents Using hook_node_a
Page 23 and 24: Table of Contents Creating a task 3
Page 25 and 26: Preface Chapter 5, Building an Admi
Page 27 and 28: Preface The system for handling thi
Page 30 and 31: Developing for Drupal 7 Drupal is a
Page 32 and 33: However, what we do want to start w
Page 34 and 35: The Operating System Chapter 1 Wind
Page 36 and 37: Chapter 1 Drupal core is the founda
Page 40 and 41: Chapter 1 The responsibility of the
Page 42 and 43: Chapter 1 While one could imagine t
Page 44 and 45: Chapter 1 We assume that you have y
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Page 49 and 50: Creating Your First Module We are g
Page 51 and 52: Creating Your First Module As obvio
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Drupal’s Theme Layer Theme engine
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Drupal’s Theme Layer Preprocess f
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Drupal’s Theme Layer A Drupal the
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Drupal’s Theme Layer The theme()
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Drupal’s Theme Layer Now, if you
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Drupal’s Theme Layer A similar pr
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Drupal’s Theme Layer Now, that wa
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Drupal’s Theme Layer • #suffix:
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Drupal’s Theme Layer Two powerful
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Drupal’s Theme Layer 'menu_tree__
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Drupal’s Theme Layer If a functio
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Drupal’s Theme Layer We've also s
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Drupal’s Theme Layer Summary You'
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Theming a Module After all, if you
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Theming a Module * Enables a single
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Theming a Module * First draft! * *
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Theming a Module Theming a Drupal b
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Theming a Module Converting a theme
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Theming a Module if (is_array($elem
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Theming a Module Notice that the .b
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Theming a Module } $block['content'
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Theming a Module } 'variables' => a
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Theming a Module } // Theme the use
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Theming a Module // Create links fo
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Theming a Module } // Load the acco
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Theming a Module * - $user: The use
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Theming a Module Summary In this ch
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Building an Admin Interface Startin
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Building an Admin Interface $items[
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Building an Admin Interface 'access
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Building an Admin Interface Each ar
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Building an Admin Interface Other p
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Building an Admin Interface Each el
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Building an Admin Interface Drupal
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Building an Admin Interface This is
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Building an Admin Interface Form su
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Building an Admin Interface A short
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Building an Admin Interface } retur
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Building an Admin Interface PHP mai
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Building an Admin Interface Impleme
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Building an Admin Interface Debuggi
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Building an Admin Interface This te
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Working with Content Drupal 7 intro
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Chapter 6 The Schema API allows dat
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'fields' => array( 'aid' => array(
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Chapter 6 'fieldable' => TRUE, 'ent
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Chapter 6 The return value from the
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Chapter 6 In our case, we defined t
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Chapter 6 Most entity operations in
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[ 165 ] Chapter 6 This callback sim
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Chapter 6 This page will simply gen
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Chapter 6 This hook defines a new f
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Submit callback The submit callback
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Chapter 6 // Save the initial revis
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Chapter 6 Master/slave database con
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Chapter 6 array($artwork->aid => $a
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Chapter 6 'access arguments' => arr
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Chapter 6 } foreach ($artworks as $
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Creating New Fields In the last cha
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Chapter 7 Although an advanced topi
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Chapter 7 The most important magic
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Chapter 7 } } '#type' => 'select',
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Chapter 7 Exposing fields to the Fo
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Chapter 7 $element['width'] = array
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Chapter 7 if ($widget['type'] == 'd
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Chapter 7 } return; 'field_ui_field
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Chapter 7 } function theme_dimfield
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Chapter 7 } '@height' => $item['hei
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Chapter 7 } else if ($settings['uni
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Chapter 7 We can, of course, have m
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Chapter 7 To demonstrate how entity
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[ 209 ] Chapter 7 Now look at that
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Drupal Permissions and Security Per
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Chapter 8 The preceding code checks
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Chapter 8 If we had accidentally ru
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Chapter 8 The user_access() functio
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In the first case, Are we looking a
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Chapter 8 Declaring your own access
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} Chapter 8 'page callback' => 'exa
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Chapter 8 if (!flood_is_allowed('co
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[ 227 ] Chapter 8 Enabling permissi
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Chapter 8 } $permissions = array( '
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Chapter 8 This approach is the prop
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Chapter 8 Running access checks on
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Chapter 8 Handling AJAX callbacks s
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Chapter 8 As a result, we cannot tr
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Chapter 8 This allows us to pass a
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Node Access Out-of-the-box, Drupal
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Chapter 9 The Node Access API allow
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* - "delete" * - "create" * @param
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Chapter 9 if (!user_access('access
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Chapter 9 } if (module_implements('
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Chapter 9 hook_node_access() is the
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Chapter 9 Note that the {node_acces
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Chapter 9 The basic permission 'cre
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Chapter 9 It is a good idea to writ
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Chapter 9 On node listing pages, th
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Chapter 9 Writing a complete node a
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• Can this user bypass node acces
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Chapter 9 For our test module, we w
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Chapter 9 When hook_node_access_rec
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Chapter 9 A few things to consider
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Chapter 9 Security considerations T
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Chapter 9 Rebuilding the {node_acce
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Chapter 9 Using the new hook_node_a
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Chapter 9 We may alter any element
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Chapter 9 } // Check anonymous user
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Chapter 9 // Check the permission.
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Chapter 9 The key to Devel Node Acc
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Chapter 9 In the preceding case, th
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JavaScript in Drupal JavaScript is
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Chapter 10 Adding JavaScript and CS
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Chapter 10 When a JavaScript librar
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The following code adds a system CS
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Chapter 10 The second argument can
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Chapter 10 From here onwards, when
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Chapter 10 If a renderable array is
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Chapter 10 Drupal specific JavaScri
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Chapter 10 There are three ways var
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Chapter 10 AJAX helpers Included in
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The callback function hello_world_s
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Chapter 10 Once the response is set
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ajax_command_prepend To add content
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Working with Files and Images Drupa
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Chapter 11 It is very important tha
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Chapter 11 In order to open files f
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Chapter 11 Stream wrappers If you'v
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Chapter 11 In some cases you may no
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Chapter 11 A read-only stream wrapp
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Chapter 11 } 'type' => STREAM_WRAPP
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Chapter 11 For full details of thes
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Chapter 11 After this setup, we sta
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Chapter 11 This is all very cool, b
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Chapter 11 This is where you can st
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Chapter 11 • form callback: If yo
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Chapter 11 Finally we can make the
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Chapter 11 Pretty cool right? Howev
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Chapter 11 As you can see, there is
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Installation Profiles This chapter
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Chapter 12 Profile modules and them
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Enabling modules Just like modules
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Chapter 12 • display_name: A huma
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Next, let's create a form to enter
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Chapter 12 Notice that $install_sta
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Chapter 12 Here, the task that sets
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Chapter 12 Each row being added to
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Chapter 12 // URL filter. 'filter_u
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Chapter 12 'locale' => 'en', ), //
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Database Access Although Drupal 7 h
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Appendix A Result objects The retur
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Appendix A The join() methods all r
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[ 369 ] Appendix A The db_insert()
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Appendix A A Merge query says, in e
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Appendix A Slave servers Drupal als
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Security Throughout this book, we h
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Filtering The following guidelines
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First, whenever we write a query ag
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Appendix B There are both RSS feeds
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ajax_command_alert command 309 ajax
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Drupal, subsytems blocks 20 code te
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form handling 229 forms access chec
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K key() method 371 L label property
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evision handling 175 revisions hand
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U unit test 49 update queries 370 u
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Drupal 7 ISBN: 978-1-84951-286-2 Pa
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