Fields in Core: How to create a custom field

FIELDS IN CORE:
HOW TO CREATE A CUSTOM
FIELD
By Ivan Zugec

WHO AM I?

• Name: Ivan Zugec

• Drupal username: Ivan Zugec

• Twitter: http://twitter.com/zugec

• Blog: http://zugec.com

SESSION AGENDA

• What’s new in Drupal 7

• Understanding ﬁelds

• How to create a ﬁeld

• Custom formatters

• Documentation

• Q&A

WHAT’S NEW IN DRUPAL 7

• InDrupal 6 we used the
CCK module to add ﬁelds
into nodes


• In
Drupal 7 a lot of CCK’s functionality has been moved into
core

• Not all CCK modules made it into core


• “Node reference” and “User reference” moved to http://
drupal.org/project/references

• “Fieldset” moved to http://drupal.org/project/ﬁeld_group

• “Contentpermission” moved to http://drupal.org/project/
ﬁeld_permissions


• Drupal 7 ships with text, options, number and list

• File and image ﬁeld all in core

UNDERSTANDING FIELDS

• Pieceof functionality
attached to an entity (node,
taxonomy, etc...)

• Example: Date module


• Fields
have 4 major
components

• Field

• Field type

• Widget

• Formatter


• Field

• field.module, field.info and field.install

/**
* Implements hook_field_schema().
*/
function text_field_schema($field) {
switch ($field['type']) {
case 'text':
$columns = array(
'value' => array(
'type' => 'varchar',

• Field type 'length' => $field['settings']['max_length'],
'not null' => FALSE,
),
);
break;

• How the field will be stored
case 'text_long':

....

in the database
break;
}
$columns += array(
'format' => array(
'length' => 255,

• Using hook_field_schema ),

);
return array(
'columns' => $columns,

• Using hook_field_info 'indexes' => array(

),
'format' => array('format'),

'foreign keys' => array(
'format' => array(
'table' => 'filter_format',
'columns' => array('format' => 'format'),
),
),
);


• Widget

• Form element a user will use
to enter in the data


• Formatter

• How to data will be
displayed

HOW TO CREATE A FIELD

• Createa custom
“Collaborators” field

• Module will be called
“collabfield”

• Unlimited value field with a
Name, Role and Link text
fields within


• Createa module called
collabfield

• Createcollabfield.info,
collabfield.install and
collabfield.module files

collabﬁeld.info

; $Id$

name = Collaborator field
description = Custom collaborator field.

dependencies[] = field_ui

core = 7.x

collabﬁeld.install
<?php
// $Id$

/**
* Implements hook_install().
*/

function collabfield_install() {
}

/**
* Implements hook_uninstall().
*/

function collabfield_uninstall() {
}

/**
collabﬁeld.install
* Implementation of hook_field_schema().
*/
function collabfield_field_schema($field) {
if ($field['type'] == 'collabfield') {
$schema['columns']['name'] = array(
'length' => '255',
);

$schema['columns']['role'] = array(
'length' => '255',
);

$schema['columns']['link'] = array(
'length' => '255',
);

$schema['indexes'] = array(
'name' => array('name'),
'role' => array('role'),
'link' => array('link'),
);
return $schema;
}

collabﬁeld.module
<?php
// $Id$

/**
* Implementation of hook_field_info().
*/
function collabfield_field_info() {
return array(
'collabfield' => array(
'label' => t('Collaborator'),
'description' => t('Custom collaborators field.'),
'default_widget' => 'collabfield_collabfield_form',
'default_formatter' => 'collabfield_default',
),
);
}

collabﬁeld.module

/**
* Implementation of hook_field_is_empty().
*/
function collabfield_field_is_empty($item, $field) {
if ($field['type'] == 'collabfield') {

if (empty($item['name']) && empty($item['role']) && empty($item['link'])) {
return TRUE;

}

}
return FALSE;
}


• Create a widget

• Use hook_field_widget_info
to setup field

• Use
hook_field_widget_form for
the actual form element

/**
* Implements hook_field_widget_info().
*/
function collabfield_field_widget_info() {
return array(
'collabfield_collabfield_form' => array(
'label' => t('Collabfield form'),
'field types' => array('collabfield'),
'behaviors' => array(
'multiple values' => FIELD_BEHAVIOR_DEFAULT,
//Use FIELD_BEHAVIOR_NONE for no default value.
'default value' => FIELD_BEHAVIOR_DEFAULT,
),
),
);
}

/**
* Implementation of hook_field_widget_form().
*/
function collabfield_field_widget_form(&$form, &$form_state, $field, $instance, $langcode, $items, $delta, $element) {

$base = $element;
if ($instance['widget']['type'] == 'collabfield_collabfield_form') {
$widget = $instance['widget'];
$settings = $widget['settings'];

$element['name'] = array(
'#type' => 'textfield',
'#title' => t('Name'),
'#default_value' => isset($items[$delta]['name']) ? $items[$delta]['name'] : NULL,
);
$element['role'] = array(
'#title' => t('Role'),
'#default_value' => isset($items[$delta]['role']) ? $items[$delta]['role'] : NULL,
);
$element['link'] = array(
'#title' => t('Link'),
'#default_value' => isset($items[$delta]['link']) ? $items[$delta]['link'] : NULL,
'#element_validate' => array('_collabfield_link_validate'),
);

}
return $element;
}


• To validate an element add #element_validate to the speciﬁc
element
$element['link'] = array(
'#title' => t('Link'),
'#default_value' => isset($items[$delta]['link']) ? $items[$delta]['link'] : NULL,
'#element_validate' => array('_collabfield_link_validate'),
);

/**
* Validation callback for a collabfield link element.
*/
function _collabfield_link_validate($element, &$form_state, $form) {
$value = $element['#value'];
if (!empty($value) && !valid_url($value, TRUE)) {
form_error($element, t('Invalid URL.'));
}

}


• Drupalships with three form element validators in
ﬁeld.module

• _element_validate_integer()

• _element_validate_integer_positive()

• _element_validate_number()


• Create a formatter

• Use
hook_ﬁeld_formatter_info
to setup a formatter

• Use
hook_ﬁeld_formatter_view
for the actual formatter

/**
* Implements hook_field_formatter_info().
*/
function collabfield_field_formatter_info() {
return array(
'collabfield_default' => array(
'label' => t('Default'),
'field types' => array('collabfield'),
),
);
}

/**
* Implements hook_field_formatter_view().
*/
function collabfield_field_formatter_view($entity_type, $entity, $field, $instance, $langcode, $items, $display) {
$element = array();

switch ($display['type']) {
case 'collabfield_default':
foreach ($items as $delta => $item) {
$element[$delta]['#markup'] = theme('collabfield_formatter_default', $item);
}
break;
}

return $element;
}

CUSTOM FORMATTERS

• Formatter to change default term reference link formatter

• Create as custom module

• Change URL taxonomy/term/[tid] to whatever/[tid]

CUSTOM FORMATTERS
/**
* Implements hook_field_formatter_info().
*/
function termpathfield_field_formatter_info() {
return array(
'termpathfield_term_reference_link' => array(
'label' => t('Custom path link'),
'field types' => array('taxonomy_term_reference'),
'settings' => array(
'taxonomy_custom_url' => 'taxonomy/term/[tid]',
),
),
);
}

CUSTOM FORMATTERS
/**
* Implements hook_field_formatter_settings_form().
*/
function termpathfield_field_formatter_settings_form($field, $instance, $view_mode, $form, &$form_state) {
$display = $instance['display'][$view_mode];
$settings = $display['settings'];
$form = array();

if ($display['type'] == 'termpathfield_term_reference_link') {
$form['taxonomy_custom_url'] = array(
'#title' => t('Custom term page URL'),
'#default_value' => $settings['taxonomy_custom_url'],
'#required' => TRUE,
);
}

return $form;
}

CUSTOM FORMATTERS
/**
* Implements hook_field_formatter_settings_summary().
*/
function termpathfield_field_formatter_settings_summary($field, $instance, $view_mode) {
$display = $instance['display'][$view_mode];
$settings = $display['settings'];
$summary = '';

if ($display['type'] == 'termpathfield_term_reference_link') {
$summary = $settings['taxonomy_custom_url'];
}

return $summary;
}

CUSTOM FORMATTERS
/**
* Implements hook_field_formatter_view().
*/
function termpathfield_field_formatter_view($entity_type, $entity, $field, $instance, $langcode, $items, $display) {
$result = array();

switch ($display['type']) {
case 'termpathfield_term_reference_link':
foreach ($items as $delta => $item) {
$term = taxonomy_term_load($item['tid']);

$uri_path = str_replace('[tid]', $term->tid, $display['settings']['taxonomy_custom_url']);
$uri = url($uri_path, array('absolute' => TRUE));

$result[$delta] = array(
'#type' => 'link',
'#title' => $term->name,
'#href' => $uri,
);
}
break;
}

return $result;
}

DOCUMENTATION

• http://api.drupal.org

• Field Types API

http://api.drupal.org/api/
drupal/modules--field--
field.api.php/group/
field_types/7

DOCUMENTATION

• Other core ﬁeld modules

• list.module, number.module,
options.module and
text.module

• modules/ﬁelds/modules

DOCUMENTATION

• Examples for Developers

• http://drupal.org/project/
examples

Fields in Core: How to create a custom field

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