Drupal Views development

Developing for the Views 7.3 API Frédéric G. MARAND aka fgm aka OSInet

Session summary
Concepts
Basic integration: default views & embedding
Drupal-style integration: lifecycle hooks
Views-style integration: handlers & plugins
Going further

1. Concepts

Concepts: Is this for you ?
Views UI
PHP5 OOP
Module development

Concepts: Views API, why care ?
Code-based views
Views-based code
Views theming
Extra view types

Concepts: Why care ? More extras
Handlers...
Area contents
Argument types
Field types
Filters
Relationships
Sort rules
Plugins...
Access controls
Argument defaults
Argument validators
Caching mechanisms
Exposed forms
Localization
Pager types
Query engines
Layouts

Concepts: I'm sold: what is a View ?
A pre-built query
SQL, NoSQL, WS...
From Views UI or from code
On known entities ....
.... not in the EFQ sense

Concepts: What is a View, again ?
A parametric query
Arguments
Exposed filters
A query with formatted results
Layout plugins: Display, Style, Row
Themable
Yes, it means a REPORT

Concepts: a report for coders
The « exportable » concept
Default views
Normal views
Overridden views
Features, anyone ?

Concepts: enough talk
Time for some <?php hooks(); ?>

2. Basic default/embed

Basic: Hello, Views
hook_views_api()
Version matching
Component location
THE hook in your module

Basic: HVA demo
(Switch to code view)

Basic: intermezzo Intermezzo: hooks & OO in Views Skip to HVD

Basic: hooks & OO in Views
Hooks
Passive observer pattern
Parent is in charge
can override child
can extend child
Implementations alter sibling results
« horizontal »
Views OO
Inheritance
Children are in charge
can override parent
can extend parent
No sibling results
« vertical »

Basic: Views objects
views_db_object
view
view_display
views_object
views_handler
views_plugin … And a small collection of miscellaneous classes

Basic: Views hooks
Pseudo-hooks
Declare a list of data
Build a registry
Use exactly one specified piece of data
HV Data, HV DV, HV Plugins, HV QS…
True hooks
Accumulators: lifecycle hooks
Alter hooks: HV QA, HV ALA

Basic: supporting custom tables
hook_views_data
Base tables
[base] view type = base table
The [table] array
Linked tables
POV: From the table being defined
...to another (left) table via a (left) field
...iteratively
...until a base table is found at the far left
Do not forget relationship handlers. Just not here.
Yes, that's a pseudo-hook
Back to Intermezzo

Basic: altering the schema
hook_views_data_alter
Plain Old Drupal Alterator
Use cases
Expose new fields in a table supported by another module
Add new sorts, filters... to another module
HVD/HVDA: Invocation time ?

Basic: HVD demo
Add Views support to dblog.module (Switch to code view)

Basic: code-based Views
hook_views_default_views
Build a view object in code
PHP as a DSL ?
Didn't we see this somewhere else in Drupal ?
Work process
Views UI to/from code
Single or multiple view files
<?php ?> wrapper
File names

Basic: HVDV demo
Provide a default view to dblog.module (Switch to code view)

Basic: a page with a view
views_embed_view($name, $display = 'default')
The good:
Dead simple to use
Argument passing
The bad:
Default display ? Really ?
$view unavailable
The ugly:
Display side effects

Basic: a page with a better view
view::execute_display()
Still side effects
But more control: $view is available
view::preview()
Core of views_embed_view()
Can refine the process as needed
$view available

3. Drupal-style: lifecycle hooks

Drupal style: early lifecycle hooks
A bunch of traditional hooks
From view initialization to result rendering:
HV_pre_view :
start, no work done
Alter view with view::attachment_(before|after)
HV_pre_build :
Displays initialized
Alter view with view::attachment_(before|after)
Before query building

Drupal style: query lifecycle hooks
HV_query_alter()
Modify the query
Beware the aliases !
HV_query_substitutions
Pseudo-hook: registry of ***CURRENT_USER*** -like
Uncommon in « userland »
HV_pre_execute
nodeAccess not yet applied

Drupal style: render lifecycle hooks
Query executed
HV_pre_render
After the pre_render() methods in handlers
HV_admin_links_alter
Damage control on side effects
Example: hide inline edit controls in list
Theming
Another story in its own right

4. Views style: handlers & plugins

Views: handlers and plugins
views_db_object : the helpful parent
definition
options
forms
views_handler
define the query: fields, ordering, conditions, relations
define area content
views_plugin
everything else
including the query /engine/

Views: « layout » plugins
Display
Outer content
Define format: block, page, feed
Style
Row set
Grid, table, list...
Row
Optional: some style plugins (table) have to intervene between rows
Typical: views_plugin_row_fields

Views: access plugins
Avoid running unauthorized queries
Mandatory
Built -in:
None
Permission (BCP)
Role

Views: query plugin
Build and run the actual query
Mandatory
Built-in: SQL via DBTNG (db_api in D6)
Opportunity to interface non-SQL services with Views. Samples/experiments:
EntityFieldQuery http://drupal.org/project/efq_views
MongoDB http://bit.ly/mongodbviews
Web Services http://bit.ly/extendrviews
SPARQL, YQL, Wolfram Alpha, ApacheSolr...

Views: other plugins
Argument plugins
Not arguments themselves
Default plugins
Validation plugins
Cache plugins
Built-in: none, basic time-based
Optional: views_content_cache
Others
Pagers, exposed_form, localization (none / core)

Views: implementing plugins
Declare to Views
hook_views_plugins
views_discover_plugins
File layout
D7 autoloading: <module>.info
One per plugin
Naming conventions
Alterability
hook_views_plugins_alter()

Views: access plugin demo
Write a variable-based access control plugin (Switch to code view)

Views: access plugin questions
Views caching ?
Non-Views caching ?

Views: simple handlers
Filter handlers
Add conditions rules
Translate to WHERE or HAVING for SQL
Express a problem space condition as a (set of) query engine conditions
Sort handlers
Add sorting rules
Translate to ORDER BY for SQL
Express a problem space sorting as a query ordering

Views: field handlers
Basic
Expose a DB column under its own name
Evolved
Expose several aliases from a single column
Synthesize several columns into one field

Views: complex handlers
Relationships
Remember implicit joins ? Make them explicit
Allow multiple named join paths from table to base
Arguments
Basically filters
But context-injected
Can modify page: title, breadcrumbs...
Can modify display: eg summary mode
Aggregate GROUP BY support ?
argument & field & filter & sort

Views: area handlers
Areas ?
Header
Footer
Empty
Why ?
No more in-DB PHP to have dynamic area content
No more embedded views just for dynamic area content
Why handlers ?
Field handlers for the #global virtual table

Views: implementing handlers
Declare to Views
No more hook_views_handlers
Properties: hook_views_data[_alter]
D7 autoloading: <module>.info
File layout: like plugins

Views: area handler demo
(Switch to code view)

5. Going further

Going further: more info
This is just an intro!
Merlinofchaos' et alii book about Views 2 still relevant
http://bit.ly/cckviewspanels
Online
http://views.doc.logrus.com/
Advanced Help in your own site
Freenode IRC :
Work on Views itself: #drupal-views
Support for your Views code: #drupal and #drupal-contribute (for contrib)

The mandatory plug
This session is only an excerpt from the hands -on OSInet DR-713 course
7-hour hands-on workshop
Available in English and French
On-demand in other languages
OSInet is a state registered french training provider with a full Drupal training syllabus
From content creator... to site builder ...
...to advanced module developer [email_address]

The « other » mandatory plug We're hiring ! [email_address]

</Developing for the Views 7.3 API Frédéric G. MARAND aka fgm aka OSInet>

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Drupal Views development

by Frédéric Marand on Mar 16, 2011

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Drupal Views development — Presentation Transcript