Cursor rule

1---
2description: 
3globs: 
4alwaysApply: false
5---
6# Moodle Error Handling
7 
8## Purpose
9Ensure consistent and proper error handling across all Moodle PHP code for better debugging and user experience.
10 
11## Instructions
12When implementing error handling in Moodle PHP code, follow these practices:
13 
141. **Use Moodle Exceptions**: Use `moodle_exception` and specific exception types
152. **Parameter Validation**: Use `required_param()`, `optional_param()` with proper validation
163. **Debugging**: Use `debugging()` for development, `error_log()` for critical errors
174. **User Feedback**: Provide meaningful error messages using language strings
185. **Graceful Degradation**: Handle errors gracefully without breaking the user experience
196. **Logging**: Use Moodle's logging system for important events and errors
207. **Context Information**: Include relevant context in error messages
218. **Error Recovery**: Implement recovery mechanisms where possible
22 
23## Examples
24 
25```php
26<?php
27// File: ./includes/error_handling_example.php
28 
29/**
30 * Example of proper error handling in Moodle
31 */
32function process_user_action($userid, $action) {
33    global $DB, $USER;
34    
35    try {
36        // Parameter validation
37        $userid = required_param('userid', PARAM_INT);
38        $action = required_param('action', PARAM_ALPHA);
39        
40        // Validate user exists
41        $user = $DB->get_record('user', ['id' => $userid], '*', MUST_EXIST);
42        
43        // Check permissions
44        if (!has_capability('moodle/user:edit', context_user::instance($userid))) {
45            throw new moodle_exception('nopermission', 'core');
46        }
47        
48        // Perform action with error handling
49        switch ($action) {
50            case 'update':
51                $result = update_user_profile($userid);
52                break;
53            case 'delete':
54                $result = delete_user_data($userid);
55                break;
56            default:
57                throw new moodle_exception('invalidaction', 'core');
58        }
59        
60        // Log successful action
61        \core\event\user_action_performed::create([
62            'objectid' => $userid,
63            'relateduserid' => $USER->id,
64            'other' => ['action' => $action]
65        ])->trigger();
66        
67        return $result;
68        
69    } catch (dml_exception $e) {
70        // Database errors
71        debugging('Database error: ' . $e->getMessage(), DEBUG_DEVELOPER);
72        throw new moodle_exception('databaseerror', 'core');
73        
74    } catch (moodle_exception $e) {
75        // Re-throw Moodle exceptions
76        throw $e;
77        
78    } catch (Exception $e) {
79        // Unexpected errors
80        error_log('Unexpected error in process_user_action: ' . $e->getMessage());
81        throw new moodle_exception('unknownerror', 'core');
82    }
83}
84 
85/**
86 * Graceful error handling with user feedback
87 */
88function display_user_data($userid) {
89    try {
90        $userdata = get_user_data($userid);
91        echo format_string($userdata->name);
92        
93    } catch (moodle_exception $e) {
94        // Show user-friendly error
95        echo html_writer::div(
96            get_string('error_loading_user', 'core'),
97            'alert alert-warning'
98        );
99        
100        // Log detailed error for administrators
101        debugging('Error loading user data: ' . $e->getMessage(), DEBUG_DEVELOPER);
102    }
103}
104```
105 
106## Exceptions
107- Critical system errors may require different handling approaches
108- Third-party integrations may have specific error handling requirements
109