camas

---

Camas is a OO design minimal React authorization library.

Live demo

• TypeScript friendly
• Zero dependencies
• React Hooks
• Scalable
• Easy to test
• Only 500 Bytes after gzip

Installation

Use npm:

$ npm install camas --save

Use yarn:

$ yarn add camas

Policies

Camas is focused around the notion of policy classes. I suggest that you put these classes in src/policies. This is a simple example that allows updating a post if the user is an admin, or if the post is unpublished:

interface Post {
  title: string;
  body: string;
  isPublished: boolean;
}
 
interface User {
  username: string;
  isAdmin: boolean;
}
 
class PostPolicy {
  protected user: User;
 
  construtor(context: { user: User }) {
    this.user = context.user;
  }
 
  update(post: Post) {
    return this.user.isAdmin || !post.isPublished;
  }
}

As you can see, this is just a plain JavaScript class.

Usually you can set up a base class to inherit from:

class BasePolicy {
  protected user: User;
 
  construtor(context: { user: User }) {
    this.user = context.user;
  }
}
 
class PostPolicy extends BasePolicy {
  update(post: Post) {
    return this.user.isAdmin || !post.isPublished;
  }
}

Context provider

import { Provider } from 'camas';
 
const App = () => (
  <Provider context={{ user: currentUser }}>
    <Routes />
  </Provider>
);

Camas will pass context to the policy class when initializing it.

Consume policy

Using hook

import { usePolicy } from 'camas';
 
const PostList = ({ posts }) => {
  const postPolicy = usePolicy(PostPolicy);
 
  return (
    <div>
      <ul>
        {posts.map(post => (
          <li>
            {post.title}
            {postPolicy.update(post) && <span>Edit</span>}
          </li>
        ))}
      </ul>
    </div>
  );
};

Using component

import { Authorize } from 'camas';
 
const PostList = ({ posts }) => {
  return (
    <div>
      <ul>
        {posts.map(post => (
          <li>
            {post.title}
            <Authorize with={PostPolicy} if={policy => policy.update(post)}>
              <span>Edit</span>
            </Authorize>
          </li>
        ))}
      </ul>
    </div>
  );
};

Testing

Since polices are just plain classes, testing your polices can be very easy.

Here is a simple example with jest:

import PostPolicy from './PostPolicy';
 
descript('PostPolicy', () => {
  const admin = {
    isAdmin: true;
  };
 
  const normalUser = {
    isAdmin: false;
  }
 
  const publishedPost = {
    isPublished: true;
  }
 
  const unpublishedPost = {
    isPublished: false;
  }
 
  it("denies access if post is published", () => {
    expect(new PostPolicy({ user: normalUser }).update(publishedPost)).toBe(false);
  });
 
  it("grants access if post is unpublished", () => {
    expect(new PostPolicy({ user: normalUser }).update(unpublishedPost)).toBe(true);
  });
 
  it("grants access if post is published and user is an admin", () => {
    expect(new PostPolicy({ user: admin }).update(publishedPost)).toBe(true);
  });
});

API

Provider

Props

• context - Camas passes conetxt to the policy class when initializing it.

<Provider conetxt={{ user: currentUser }}>
  <App />
</Provider>

Authorize

Props

• with - Policy class.
• if - Check function for the policy, it accepts the policy instance as it's first argument.
• fallback - Fallback element when policy check now pass.

<Authorize with={PostPolicy} if={policy => policy.show()} fallback={<div>You are not allow to view these posts.</div>}>
  <PostList />
</Authorize>

usePolicy(...policies)

The usePolicy hook receive policies class as it's arguments and return instances of them.

const postPolicy = usePolicy(PostPolicy);

withPolicies(policies)

A HOC injects policy instance to class component.

@withPolicies({
  postPolicy: PostPolicy,
})
class PostList extends React.Component {
  render() {
    const { posts, postPolicy } = this.props;
    return (
      <div>
        <ul>
          {posts.map(post => (
            <li>
              {post.title}
              {postPolicy.update(post) && <span>Edit</span>}
            </li>
          ))}
        </ul>
      </div>
    );
  }
}

authorize(policy, check, fallback)

A HOC to apply policy to the component.

@authorize(
  PostPolicy,
  ({ policy }) => policy.show(),
  <Unauthorized />
)
class PostList extends React.Component {
  render() {
    return ...
  }
}

License

MIT