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fields

---
title: "Database Fields for Moodle 4.4.3"
last_updated: "2024-10-02"
tags: 
  - "mod_data"
  - "datafield"
  - "plugin"
  - "subplugin"
---

Database Fields for Moodle 4.4.3

This documentation is a work-in-progress. Feel free to contribute.

The Database activity in Moodle allows users to create structured collections of data. It supports various predefined field types like text, date, and URL. Developers can extend Moodle by creating custom field types, which are beneficial for specialized uses like discipline-specific, institution-specific, or module-specific needs.

Custom Field Types Examples​

  • Discipline-specific field types:
    Example: "Protein PDB code" allows users to input a PDB code, displaying a 3D viewer of the protein structure or linking to molecular databases.

  • Institution-specific field types:
    Example: "Library reference number" allows users to input reference numbers that convert into direct links for local library services.

  • Module-specific field types:
    Example: "Wiki page" field provides a dropdown list of wiki pages, linking database entries to specific wiki content.

File Structure for Field Sub-Plugins​

Custom database field sub-plugins are located in /mod/data/field. Each plugin resides in a separate subdirectory and contains several required files.

Key Files for Field Plugins​

1. field.class.php (Required)​

Defines the field type and its behaviors within a class named data_field_[pluginname]. This class must extend the data_field_base base class.

Key Functions to Override:​

  • display_add_field($recordid = 0): Generates HTML for adding or editing a record.
  • display_browse_field($recordid, $template): Generates HTML for browsing records.
  • update_content($recordid, $value, $name = ''): Saves user input data.
  • get_sort_sql($fieldname): Defines SQL for sorting records by the field.
  • get_content_value($value): Retrieves and transforms the data for display.

Class Locations and Autoloading​

Custom field definitions reside in field.class.php. Moodle 4.4.3 does not autoload this file, so it is recommended to follow Moodle's autoloading guidelines to ensure future compatibility.

Field Configuration Form​

File Path: /mod.html (Required)

This file defines the form for adding or editing the field's configuration. Moodle’s Form API is used to create input elements. Here is an example:

$mform->addElement('text', 'fieldname', get_string('fieldname', 'datafield_[pluginname]'), 'size="30"');
$mform->setType('fieldname', PARAM_TEXT);
$mform->addRule('fieldname', null, 'required', null, 'client');

Note: The form retains some legacy elements, so developers are encouraged to update it to follow Moodle's Form API guidelines.

Security Best Practices​

When creating custom fields, ensure inputs are properly validated and sanitized. Use Moodle's security functions, such as required_param() and optional_param(), to prevent SQL injection and XSS attacks.

Example:

$input = required_param('input', PARAM_ALPHANUM);

Testing and Compatibility​

Custom field plugins should be tested for compatibility across Moodle 4.4.3’s supported environments, including:

  • PHP 8.1
  • MariaDB 10.6.7
  • MySQL 8.0
  • PostgreSQL 13
  • MSSQL 2017
  • Oracle 19c

Use Moodle’s unit testing framework for automated testing to ensure functionality across different environments.

Form API Enhancements in Moodle 4.4.3​

Moodle 4.4.3 introduces improvements to the Form API for better accessibility and user experience. Ensure that custom field forms are:

  • Mobile-responsive
  • Accessible
  • Optimized for modern browsers

Follow Moodle's accessibility guidelines to make sure your forms work well for all users.

Version Control and Deployment​

To ensure smooth development and deployment of custom field types:

  • Use Moodle’s Git version control system.
  • Maintain proper versioning for compatibility with Moodle's plugin directory and version upgrades.

Developers should submit and maintain their plugins in the Moodle Plugin Directory.

Key Considerations for Moodle 4.4.3:​

  • Use updated coding standards to align with Moodle's guidelines for PHP 8.1.
  • Implement security features to avoid vulnerabilities.
  • Ensure compatibility across Moodle's supported environments.
  • Follow best practices for form creation and plugin configuration management.

By following these guidelines, developers can ensure their custom field types are secure, modern, and compatible with future Moodle releases.

Last Updated: 2 October 2024