This document summarizes best practices for managing code complexity in Drupal projects. It recommends: - Building the data model around entities and relationships with minimal duplication and no cycles. - Avoid hacking core/contrib modules and putting code in the database. Use entity wrappers. - Create modules that correspond to each content type, field, and field type to keep functionality well organized. - Structure modules by content types, fields, and functionality for good modularity.

1. DrupalCamp Baltics 2015
Development Patterns:
Drupal: Managing Code Complexity
Ragnar Kurm
ragnar@waalaskala.com
http://www.slideshare.net/ragnarkurm/drupal-code-complexity
https://github.com/ragnarkurm/drupal-custom-fields.git

2. Disclaimer
This slideshow makes sense
only in workshop context

3. Have you ever felt that
code gets so complex
that you do not want/dear
to mess with it any more?
Why?
Sharing personal experience

4. Data Model
Everything is based on data model:
● Entities
– No data duplication
● Relationships
– Keep minimum
– No cycles
If you data model faulty,
then your code will faulty2
.

5. Functionality / Code
● Don't Hack Core!
● Don't Hack Contrib Modules!
● Do not put any lines of code into DB!
● Use entity_wrappers throughout
● Good Modularity
– Right purpose – usually goes along with data
structure
– Right size – not too big, but may be tiny

6. Modules along existing structure
● Whenever you need to use in code a field, a field type,
general field, a content type – create a module for it.
● Whenever you need to extend a functionality of a
contrib module – create a module for it.
● Don't hold back creating now modules, even tiny ones,
but don't create them either if you don't use it.
● Add a prefix to all of your modules, so that they would
not collide system or contrib modules.

7. Content type custom modules
● Node hooks
– Custom forms
– Validation
– Submit
● Panels
– access
– panes
● Theme hooks
● Drush extensions

8. Field and Field Type
custom modules
● Theming
– JS
– CSS
– Templates
● Add/Edit form extensions
– Validation
– Submit
● Functionality extensions
● Data processing
● Additional Panels / Views integration
● Drush extensions

9. General field custom module
Helps to render any system field in custom form
by using 1 line of code!

10. General structure example
● content_types
– x_question
– x_question_file
– x_question_options
– x_question_plaintext
● x_field
● field_types
– x_type
– x_entity_reference
– x_file
– x_image
– x_text_with_summary
● field_instances
– x_body
– x_question_file_count
– x_question_file_extensions
– x_question_file_size
● Other core and contrib module extension modules
● Other functional modules
● Other utility modules

11. Example of usage:
fields custom module
…
$form = array(
'#parents' => array(),
);
$weight = 0;
$form += x_title_addedit_form($form, $form_state, $e, $weight);
$form += x_field_points_addedit_form($form, $form_state, $e, $weight);
$form += x_field_topics_addedit_form($form, $form_state, $e, $weight);
$form += x_body_addedit_form($form, $form_state, $e, $weight);
$form += x_field_body_images_addedit_form($form, $form_state, $e, $weight);
…
return $form;

12. Case Studies
● Student test site
● Sports competition site