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Authentication

npm i @minimajs/auth

Interceptor and Authorization in MinimaJS

Interceptors and authorization play crucial roles in ensuring the security and integrity of your application. MinimaJS provides powerful tools for creating and utilizing interceptors, enabling you to implement authentication and authorization seamlessly. This documentation will guide you through the process of creating interceptors, applying them to routes, and implementing custom authorization guards.

Creating Interceptors​

Interceptors are middleware functions that intercept incoming requests before they reach the route handler. They are useful for performing tasks such as authentication, logging, or data transformation. Here's how you can create an interceptor for authentication using MinimaJS:

src/auth/interceptor.ts
import { createAuth, UnauthorizedError } from "@minimajs/auth";

export const [authMiddleware, guard, getUser] = createAuth(async () => {
  const token = getHeader("x-user-token");
  const user = await User.findByToken(token);
  if (!user) {
    throw new UnauthorizedError("Invalid credentials");
  }
  return user;
});

In this example, createAuth creates an interceptor for authentication. It expects a callback function that retrieves the user based on the provided token. If the user is not found or the credentials are invalid, it throws an UnauthorizedError.

Using Interceptors​

Once you've created the interceptor, you can apply it to routes within your application. Here's how you can use the interceptor in your application:

src/index.ts
//
import { interceptor } from "@minimajs/server";
import { authMiddleware, getUser } from "./auth/interceptor";

function getHome() {
  const user: User | undefined = getUser();
  user && console.log(`Logged in as ${user.name}`);
}

// All routes inside this module will have access to authentication
function authenticatedModule(app: App) {
  app.get("/", getHome);
}

app.register(interceptor([authMiddleware], authenticatedModule));

In this example, interceptor is used to apply the authMiddleware to the authenticatedModule. This ensures that all routes within authenticatedModule require authentication. Even if the user is not authenticated, the route handler will still be called, with null as the user.

Authorization Guards​

Authorization guards allow you to protect routes based on specific conditions or permissions. MinimaJS provides a flexible mechanism for implementing guards. You can use the guard function returned from createAuth to define custom guards:

// Applying a guard to protect the route
app.register(interceptor([authMiddleware, guard()], authenticatedModule));

You can customize guards further by specifying conditions or providing custom error messages:

// Applying a custom guard with conditions and error message
app.register(
  interceptor([authMiddleware, guard((user) => user?.type === "admin", "Not authorized")], authenticatedModule)
);

Alternatively, you can create reusable guards for common scenarios:

src/auth/guards.ts
export function admin() {
  return guard((user) => user.isAdmin, "Only admin users are allowed");
}

// Using a reusable guard
app.register(interceptor([authMiddleware, admin()], authenticatedModule));

You can also customize error messages within the guard itself:

src/auth/guards.ts
export function admin() {
  return guard((user) => {
    if (!user) {
      throw new UnauthorizedError("User not logged in");
    }
    if (!user.isAdmin) {
      throw new UnauthorizedError("User is not authorized");
    }
  });
}

// Using a guard with custom error handling
app.register(interceptor([authMiddleware, admin()], authenticatedModule));

Conclusion​

Interceptors and authorization guards are powerful features provided by MinimaJS for ensuring the security and integrity of your application. By creating custom interceptors and guards, you can implement robust authentication and authorization mechanisms tailored to your application's requirements. With MinimaJS, protecting your routes and ensuring data security has never been easier.