cancan

Authorize easily.

CanCan provides a simple API for handling authorization of actions. Permissions are defined and validated using simple allow() and can() functions respectively.

CanCan is inspired by Ryan Bates' cancan.

Installation

$ npm install --save cancan

Usage

const CanCan = require('cancan');
 
const cancan = new CanCan();
const {allow, can} = cancan;
 
class User {}
class Product {}
 
allow(User, 'view', Product);
 
const user = new User();
const product = new Product();
 
can(user, 'view', product);
//=> true
 
can(user, 'edit', product);
//=> false

API

allow(model, action, target, [condition])

Adds a new access rule.

model

Type: class (function)

Configure the rule for instances of this class.

action

Type: array|string

Name(s) of actions to allow. If action name is manage, it allows any action.

target

Type: array|class|string

Scope this rule to the instances of this class. If value is "all", rule applies to all models.

condition

Type: object|function

Optional callback to apply additional checks on both target and action performers.

Examples:

// allow users to view all public posts
allow(User, 'view', Post, {public: true});
 
// allow users to edit and delete their posts
allow(User, ['edit', 'delete'], Post, (user, post) => post.authorId === user.id);
 
// allow editors to do anything with all posts
allow(Editor, 'manage', Post);
 
// allow admins to do anything with everything
allow(AdminUser, 'manage', 'all');

can(instance, action, target[, options])

Checks if the action is possible on target by instance.

instance

Type: object

Instance that wants to perform the action.

action

Type: string

Action name.

target

Type: object

Target against which the action would be performed.

options

Type: object

Additional data for the rule condition.

Examples:

const user = new User();
const post = new Post();
 
can(user, 'view', post);

With the use of 'options' parameter

const admin = new User({role: 'administrator'});
const user = new User({role: 'user'});
 
allow(User, 'update', User, (user, target, options) => {
    if (user.role === 'administrator') {
        return true;
    }
    
    // Don't let regular user update their role
    if (user.role === 'user' && options.fields.includes('role')) {
        return false;
    }
    
    return true;
});
 
can(admin, 'update', user, {fields: ['role']);
//=> true
 
can(user, 'update', user, {fields: ['username']);
//=> true
 
can(user, 'update', user, {fields: ['role']);
//=> false

cannot(instance, action, target[, options])

Inverse of .can().

authorize(instance, action, target[, options])

Same as .can(), but throws an error instead of returning false.

License

MIT © Vadim Demedes