11. Moodle Access API: Contexts Hierarchy, Roles, Capabilities (db/access.php) & has_capability() • Moodle LMS: Enterprise Architecture & Plugin Development • Rishabh Ki Kaksha

Moodle LMS: Enterprise Architecture & Plugin Development › 11. Moodle Access API: Contexts Hierarchy, Roles, Capabilities (db/access.php) & has_capability()

45 mins

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Course Syllabus

Module 1: Moodle Core Architecture, Directory Structure & $CFG

01. Moodle Core Architecture: Modular Architecture, Directory Tree, $CFG & $SITE 02. Moodle Request Lifecycle: setup.php, config.php, $PAGE & $OUTPUT Renderers 03. The Frankenstyle Component Naming Convention & Plugin Types Taxonomy

Part 1: Core Architecture, Database & Plugin Dev

Module 2: Database Layer ($DB API) & XMLDB Schema Management

04. Moodle Database API ($DB): get_records, insert_record, execute & Safe Parameter Binding 05. XMLDB Schema Architecture: db/install.xml, upgrade.php & Automated Database Migrations 06. Complex SQL Queries with Recordsets, Pagination & Memory-Efficient Iterators

Part 2: Web Services, High-Scale MUC & AI Subsystem

Module 3: Plugin Development Lifecycle: Block, Local & Activity Modules

07. Building Custom Block Plugins (blocks/): Structure, view.php, Capabilities & Settings 08. Building Custom Local Plugins (local/): System Hooks, Navigation Injection & Cron Tasks 09. Building Custom Activity Modules (mod/): mod_form.php, Grades Integration & Completion API 10. Moodle Form API (moodleform): Validation Rules, File Manager & AJAX Elements

Module 4: Security, Access Control (Access API) & Authentication

11. Moodle Access API: Contexts Hierarchy, Roles, Capabilities (db/access.php) & has_capability() 12. Authentication Plugins (auth/): Single Sign-On (SSO), OAuth2, SAML & Active Directory Sync 13. Enrollment Plugins (enrol/): Automated Course Enrollment, Webhook Triggers & Subscriptions

Module 5: Web Services, Events & High-Scale Caching (MUC)

14. External REST Web Services: db/services.php, External API Functions & Mobile App Interop 15. Moodle Events API: Observer Pattern, Custom Events (core\event) & Triggering Webhooks 16. Moodle Task API: Ad-hoc Tasks vs Scheduled Cron Tasks with Queuing & Logging 17. Moodle Universal Cache (MUC): Definition of Cache (db/caches.php), Redis & Memory Scaling

Module 6: Enterprise AI Integration, Performance & Cloud Clustering

18. Moodle AI Subsystem (core_ai): Pluggable AI Providers, Course Summaries & Smart AI Tutors 19. Moodle Multi-Tier Enterprise Performance: Redis Session Caching, NFS Moodledata & Read Replicas 20. Production High-Availability Cloud Deployment: Dockerized Moodle, Nginx Tuning & MySQL Clustering

Interactive Lesson Studio

# 11. Moodle Access API: Contexts Hierarchy, Roles, Capabilities (db/access.php) & has_capability()

> Moodle LMS Enterprise Notes by Rishabh - Topic 11

---

### 1. The 6-Level Contexts Hierarchy 🌳

Moodle me permissions rigid tables me nahi balki Context Tree me inherit hoti hain:

```
[ CONTEXT_SYSTEM ] (Root Site Level)
        ⬇
[ CONTEXT_COURSECAT ] (Course Category)
        ⬇
[ CONTEXT_COURSE ] (Specific Course)
        ⬇
[ CONTEXT_MODULE ] (Activity / Quiz / Forum)
        ⬇
[ CONTEXT_BLOCK ] / [ CONTEXT_USER ]
```

---

### 2. Defining Capabilities in `db/access.php` & Security Enforcement

```php
// local/boost/db/access.php
$capabilities = [
    'local/boost:viewanalytics' => [
        'riskbitmask' => RISK_PERSONAL,
        'captype' => 'read',
        'contextlevel' => CONTEXT_COURSE,
        'archetypes' => [
            'teacher' => CAP_ALLOW,
            'editingteacher' => CAP_ALLOW,
            'manager' => CAP_ALLOW,
        ],
    ],
];

// PHP Script Authorization Check:
require_capability('local/boost:viewanalytics', $context);
```

---

### 3. Interview Ke 3 Sawal Is Topic Se

1. **`has_capability()` vs `require_capability()` me kya difference hai?** -> `has_capability()` boolean `true/false` return karta hai conditional UI render karne ke liye; `require_capability()` capability na hone par fatal access exception (`moodle_exception`) throw karke script execution halt karta hai.
2. **Context Preloading (`preload_course_contexts()`) SQL queries kaise reduce karta hai?** -> Course list render karte waqt hazaron context rows single query me load karke N+1 permission checks prevent karna.
3. **Role Override vs Global Role Definition me kya farak hai?** -> Global role site-wide standard defaults set karta hai; Role Override specific course context me student ko temporary moderator permissions grant karta hai.

---
**Next Topic:** 12. Authentication Plugins (auth/): Single Sign-On (SSO), OAuth2, SAML & Active Directory Sync

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