5.9 KiB
Definitively slay the mythology that module-making is a mystic domain of Drupal druids.
https://api.drupal.org/api/drupal/core%21core.api.php/group/extending/
https://api.drupal.org/api/drupal/core!core.api.php/group/hooks/
Use Git: don't be afraid to change things.
Use a debugger.
Hooks work by naming convention.
To implement a hook, take the 'hook' part off the hook name and replace it with your module's (machine) name.
When to Contribute?
When your module fills a need larger than your precise use case.
Note: If you just want to build a module, finding a module idea that one or more people have been asking for is a good way to meet a need and avoid duplication.
See also http://groups.drupal.org/ contributed-module-ideas
Finding a Drupal Function that Does What You Need
- Identify a page that produces output like what you want to see.
- Look up the page callback function for that page's menu item.
- See what functions are used (or database queries made) in the page callback function.
grep -nHR --include=*.module 'admin/appearance' modules
Error messages mean progress!
Parse error: syntax error, unexpected ';', expecting ')'
You are having an effect on the world. Or at least your local site.
Getting help
The Internet.
It's good.
Tip: Looking up Hooks
We can look up hook definitions and their function signatures the same way we look up Drupal functions, at api.drupal.org:
api.drupal.org/hook_help
api.drupal.org drupalcontrib.org
Examples project
Tip: grep
grep -nHR module_implements_alter .
./includes/module.inc:646: if ($hook != 'module_implements_alter') {
./modules/system/system.api.php:1775:function hook_module_implements_alter(&$implementations, $hook) {
Tip: Clear Caches
If something you do has no effect...
drush cr
Coding Standards
drupal.org/coding-standards
Automated Nagging
drupal.org/project/coder
Automatic Adherence
drupal.org/project/grammar_parser (obsolete?)
Development Tips
- When Something Isn't Working, Clear Caches
- When Anything's Missing, Check Permissions
- Set Your Site to Show All Errors
Lines to add to settings.php to show all notices and errors:
error_reporting(-1);
$conf['error_level'] = 2;
ini_set('display_errors', TRUE);
ini_set('display_startup_errors', TRUE);
These days i just look in the error log but it never hurts to have errors blared at your face.
The most important thing about this code is that i stole it.
I looked at how another module did it.
Implementing hooks is simply following patterns, it would be crazy not to copy.
Best practices
- Make dependenices optional when possible.
- Provide granular suggestions in theme functions so people can override when they want to.
Mauricio: http://lb.cm/mEP
Altering, Extending, and Enhancing, Drupal 8 Presentation that describes the various ways that Drupal module developers will be able to interact with Drupal 8 core to alter existing functionality, extend Drupal, and enhance it with new functionality. As well as how the various design patterns work in-case they might be useful to implement in your own projects. Mauricio: YouTube - DrupalCon New Orleans 2016: Altering, Extending, and Enhancing Drupal 8
migrations/findit_library_sync_events.yml · 8.x-1.x · Find It Program Locator / Find It Library Sync A currently fairly hard-coded module (for importing events from Cambridge public libraries) that may evolve into a general import events and programs functionality for the Find It platform. Mauricio: 1) Specify migration tag ^
Mauricio: 2) Define service https://gitlab.com/find-it-program-locator/findit_library_sync/-/blob/8.x-1.x/findit_library_sync.services.yml
findit_library_sync.services.yml · 8.x-1.x · Find It Program Locator / Find It Library Sync A currently fairly hard-coded module (for importing events from Cambridge public libraries) that may evolve into a general import events and programs functionality for the Find It platform. Mauricio: 3) Register event https://gitlab.com/find-it-program-locator/findit_library_sync/-/blob/8.x-1.x/src/EventSubscriber/FindItLibrarySyncSubscriber.php#L73
src/EventSubscriber/FindItLibrarySyncSubscriber.php · 8.x-1.x · Find It Program Locator / Find It Library Sync A currently fairly hard-coded module (for importing events from Cambridge public libraries) that may evolve into a general import events and programs functionality for the Find It platform. Mauricio: 4) Execute code https://gitlab.com/find-it-program-locator/findit_library_sync/-/blob/8.x-1.x/src/EventSubscriber/FindItLibrarySyncSubscriber.php#L25
src/EventSubscriber/FindItLibrarySyncSubscriber.php · 8.x-1.x · Find It Program Locator / Find It Library Sync A currently fairly hard-coded module (for importing events from Cambridge public libraries) that may evolve into a general import events and programs functionality for the Find It platform. Mauricio: Which is injecting credentials from settings.php
Mauricio: @mlncn I did not find the hook_node_insert example. Something similar is this https://github.com/terravoz/findit/blob/master/web/sites/all/modules/custom/findit_auto_service_provider/findit_auto_service_provider.module
terravoz/findit Drupal framework for Find It Cambridge. Contribute to terravoz/findit development by creating an account on GitHub. Mauricio: In the end, the hook_node_insert would be, check if $field_1 is set. It not, then unset($field_2)
Mauricio: I think the service implementation example for the library migration would add more value. Since it has more pieces, it will take more time to explain. So I would not try to fit the node_insert example for now
Mauricio: @mlncn 3 examples should suffice. 1) form alter 2) block plugin 3) event subscriber (find it library migration one)