File Structure

/project-root ├── drizzle.config.js # Drizzle config file ├── eslint.config.js # ESLint config file ├── .gitignore # Git ignore file ├── .README.md # README file ├── package.json ├── .env ├── model.conf # Casbin model file ├── policy.csv # Initial Casbin policy file └── src ├── app.js # Express app configuration (mounts middleware & routes) ├── server.js # Entry point to start the server ├── config │ ├── casbin.js # Casbin enforcer setup │ ├── db.js # PostgreSQL & DrizzleORM connection │ └── env.js # Loads environment variables (using dotenv) ├── drizzle │ ├── migrations # Migration files for the database │ └── schemas # Schemas for various database tables │ ├── db.js # DrizzleORM connection │ ├── migrate.js # Migrates the database using DrizzleORM │ ├── schema.js # DrizzleORM schema definition ├── controllers │ ├── auth.controller.js │ ├── content.controller.js │ └── policy.controller.js ├── middleware │ ├── auth.middleware.js # Authentication/authorization middleware │ └── error.middleware.js # Global error handling middleware ├── models │ ├── user.model.js # User model queries (DrizzleORM) │ └── policy.model.js # Policy model queries (DrizzleORM) ├── routes │ ├── auth.routes.js │ ├── content.routes.js │ └── policy.routes.js └── utils └── logger.js # Logging utility

flowchart TD

A[Client (Browser/Postman)]
B[Express.js Server]
C[Authentication & Authorization Middleware]
D[Business Logic / Controllers]
E[DrizzleORM Data Access Layer]
F[PostgreSQL Database]
G[Audit & Logging]

A --> B
B --> C
C -- Authorized? -->|Yes| D
C -- Unauthorized -->|No| H[Error Response]
D --> E
E --> F
D --- G
C --- G

Key Integration Points:

Casbin Middleware: Intercepts requests, extracts user context, and performs policy evaluation.
DrizzleORM Layer: Reads/writes users, roles, and policy rules stored in PostgreSQL.
Policy Synchronization: When policies are updated via API endpoints, the enforcer cache is refreshed to reflect new rules.

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Authentication & Authorization Middleware

function authorizationMiddleware(request, response, next): // Extract user info from request (e.g., via JWT or session) user = extractUserFromRequest(request)

// Determine the resource and action based on the request
resource = request.path
action = request.method

// Use Casbin enforcer to check if the user (or their role) is allowed
if casbinEnforcer.enforce(user.role, resource, action):
    next()  // User is authorized; proceed to controller
else:
    logUnauthorizedAttempt(user, resource, action)
    response.status(403).send("Access Denied")

For policy synchronization, when policies are added/updated/deleted through the API, call a function to reload policies in the enforcer cache.

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Database Schema

┌────────────┐ ┌─────────────┐ │ tenants │ │ roles │ │------------│ │-------------│ │ id (PK) │◄───────┐ │ id (PK) │ │ name │ │ │ name │ │ created_at │ │ │ created_at │ │ updated_at │ │ │ updated_at │ └────────────┘ │ └─────────────┘ │ │ ▼ ┌────────────┐ │ users │ │------------│ │ id (PK) │ │ username │ │ password_hash │ role_id (FK -> roles.id) │ tenant_id (FK -> tenants.id) │ created_at │ updated_at └────────────┘

      ┌─────────────────────────────────┐
      │             policies           │
      │--------------------------------│
      │ id (PK)                        │
      │ role_id (FK -> roles.id)       │  <-- 'subject' in Casbin terms
      │ object (string)                │
      │ action (string)                │
      │ created_at                     │
      │ updated_at                     │
      └─────────────────────────────────┘

Notes: tenants: Each tenant (organization) has an ID, name, and timestamps. roles: Stores role metadata (like admin, editor, viewer) and timestamps. users: Each user references a single role (if you need multiple roles per user, you’d create a user_roles pivot table) and a single tenant. policies: Each policy row references a role (subject) and specifies the allowed object and action. In Casbin terms, subject = role_id, object = object, action = action.

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Extras

Policy # department User resource path Action Auth Effect

p, csr, /dashboard, GET marketing csr /dashboard GET allow p, csr, /all-customers, GET p, csr, /lead, POST p, csr, /specific-leads, GET p, csr, /complaint, POST p, csr, /complaint, GET