dystudio / vue-browser-acl

Easy user access control in Vue for better UX. Build on top of the browser-acl package.

vue-browser-acl 🔒

Easy user access control in Vue for better UX. Build on top of the browser-acl package.

• Easily manage permissions with browser-acl using rules and/or policies (rules using classes)
• Adds v-can directive with simple syntax:
  • v-can:edit="post" an instance on the component
  • v-can:create="'Post'" (the type)
  • v-role:manager (alias, for better semantic)
• Optionally adds $can and $can.not helper functions
• Can hide v-can or to just disable v-can.disable a section, tab, or button
• Works collections of objects v-can.some or v-can.every
• Works with vue-router to guard routes
• Works with vuex and plain objects
• 2.5kb zipped

For more background on the "syntax design" read this short article: Vue user permissions through directives.

Examples

Similar to v-if removes button if user does not have permission to transfer repo.

<button v-can:transfer="repo">Transfer</button>

You don't need a subject (see global rules).

<button v-can:review>Review</button>

Has a default alias, but you can customize it.

<button v-role:manager>Delete</button>

Disables button if user does not have permission to transfer repo, or make it read-only if user cannot edit a post.

<button v-can:transfer.disable="repo">Transfer</button>
<input v-can:edit.readonly="post" type="text" name="title"/>

It works on collections, e.g. the table is shown is the user can edit at least some of the items.

<table v-can:edit.some="players">

Or all of them.

<button v-can:sell.every="players">Sell team</button>

Additionally you can use the string and array syntax.

<button v-can="'transfer repo'">Transfer repo instance</button>
<button v-can="'create Repo'">Transfer based on class</button>
<button v-can="['transfer', repo, otherArgs]">Transfer with extra argument</button>

See examples for more detailed examples: routing, vuex, etc.

Install

npm i vue-browser-acl

Setup

import Vue from 'vue'
import Acl from 'vue-browser-acl'

// example user from backend, you can provide a function
// instead in case the user retrieved asynchronously
// const user = () => store.auth.user
const user = window.__INITIAL_STATE__.user

Vue.use(Acl, user, (acl) => {
  acl.rule('view', Post)
  acl.rule(['edit', 'delete'], Post, (user, post) => post.userId === user.id)
  acl.rule('moderate', Post, (user) => user.isModerator())
})

You can pass in an actual user or a function that returns the users. This is useful if you don't have the user available right away if for instance it is fetched asynchronously.

The second param is a callback that let's you define the rules. Alternatively you can pass a preconfigured acl from the browser-acl package. This may be the better choice depending on your source bundling approach.

See browser-acl setup for how to define rules and policies (rules using classes).

As an optional third parameter you can pass an options object.

Plain objects vs function/class

The above describes setup in applications where you use ES6 classes or named constructor functions to represent your models. If you use plain objects, however, you'll have to provide a function that maps the input to string representation of what the object is.

In this example it is assumed that you have a property type on your object:

acl.subjectMapper = s => typeof s === 'string' ? s : s.type

E.g. a post:

{
    type: 'Post',   // <-- this would be used to determine what rules to apply
    title: 'ACL in the front-end',
    author: 'Wow 🦀'
}

See the details in browser-acl Subject mapper section.

Usage

You can use the module as directive, with vue-router, and as a helper function.

The v-can directive can be used in three different flavors and you can apply one or more modifiers that alters the behavior of the directive.

There are three different flavors, that to some degree can be mixed: array, string, and argument. For most cases the argument flavor would be the preferred syntax.

Array flavor

Verb, subject and optional parameters are passed as an array as the value for the directive.

<button v-can="['create', 'Post']">New</button>
<button v-can="['edit', post]">Edit</button>
<button v-can="['delete', comment, post]">Delete</button>

All arguments from the third and onwards will be passed to the ACL for evaluation.

Pros:

• Let's you pass additional arguments
• The vue compiler throws errors if you use something that doesn't exist on the component

Cons:

• Doesn't read so easily when skimming the markup

String flavor

Verb and subject is combined in a string like create Post or edit post which makes up the value of the directive.

<button v-can="'create Post'">Create</button>
<button v-can="'edit post'">Edit</button>

The string `create Post` is interpreted as the verb 'create' on the subject with name 'Post' (a class name). The string `edit post` is interpreted as the verb 'edit' on the subject that is a property on the component.

Pros:

• Easy to read

Cons:

• Cannot take additional arguments
• Since the value is a string you lose the vue-compiler errors if you refer to something that doesn't exist.

Argument flavor

In this flavor the verb is passed as an argument to the directive and for the value can use either string or array flavor with the verb removed. Additionally the value can be a plain subject object as well.

<button v-can:review>Review</button>
<button v-can:create="'Post'">New</button>
<button v-can:edit="'post'">Edit</button>
<button v-can:edit="post">Edit</button>
<button v-can:delete="[comment, post]">Delete</button>

Pros:

• Easy to read for simple cases
• Flexible value syntax
• The vue compiler throws errors if you use something that doesn't exist on the component

Cons:

• Can be slightly harder to comprehend as you make use of modifiers.

Modifiers

There are a few modifiers. Three that affects the element (hide, disable, readonly) and two that let's you evaluate multiple subjects at once (some, every).

<button v-can.disable="'delete post'">Delete</button>
<button v-can:delete.disable="post">Delete</button>
<button v-can:delete.disable.some="posts">Delete</button>

Modifiers are applied after the directive (first line) or argument (second line) and separated by a dot (third line) if several modifiers are used.

hide modifier

The hide modifier is also the default behavior so there is no need to apply it unless you want to explicitly state the behavior. It works like v-if by removing the component from the DOM.

<button v-can="'delete post'">Delete</button>
<button v-can.hide="'delete post'">Delete</button>

The above two lines has the same effect.

disable modifier

The disable modifier applies the disabled attribute to the tag, e.g. to disable a button that you are not allowed to use.

<button v-can.disable="'delete post'">Delete</button>

readonly modifier

The read only modifier applies the readonly attribute to the tag, e.g. to make an input read only if you don't have permission to edit.

Note: The readonly attribute doesn't work on all inputs. Checkboxes for instance doesn't support it.

not modifier

The not modifier reverses the query. In this example only if you cannot delete the job the div element is shown.

<div v-can:delete.not="job">Ask someone with permission to delete job</div>

some and every modifiers

The some and every arguments takes multiple subjects and will apply the same verb to all of them.

<table v-can.some="['edit', players]">
<button v-can:sell.every="players">Sell team</button>
<button v-can:delete.some="[project, sprintBoard]">Delete</button>

Note that the subjects do not need to be the some kind. In the third example above the delete button becomes visible if you either have delete permission on the project (think project owner) or you have it on the sprint board itself (a user with less permissions).

See browser-acl for more info on how to use them.

global modifier

The global modifier explicitly tells the plugin that you mean to address a global rule. In most cases this can be left out.

<!-- implicit -->
<button v-can:review>Review</button>
<button v-can="'review'">Review</button>

<!-- explicit -->
<button v-can="`review ${GlobalRule}`">Review</button>
<button v-can.global="'review'">Review</button>

Helper

You can also use the helper function $can that works much in the same way:

<settings-table :editable="$can('update', 'Setting')" :settings="settings" />

or

if (this.$can('edit', post)) {
    axios.put(`/api/posts/${post.id}`, post)
}

You can negate $can with $can.not.

If you don't want to install the helper function pass helper: false in the options.

vue-router

There are two ways to hook up the vue-router. Either during setup of the Acl or later calling the router init funtion.

Option 1: setup

Vue.use(Acl, user, (acl) => {
    ..
}, {router});

Option 2: init function

acl.router(router)

You configure routes by adding can meta property to the route. E.g. if a router requires create permissions for "Post":

{
  name: 'new-post',
  path: 'posts/create',
  component: PostEditor,
  meta: {
    can: 'create Post',
    fail: '/posts'
  }
}

Limitation: Unlike with the directive and the helper you will not have access to class instances. E.g you cannot use a can: 'delete post' as this assumes you have a Post instance already.

role is a synonym for can. So if you have rules that are more role-like you can use this instead. E.g. role: 'admin'.

Async evaluation is possible providing a callback that returns a promise like this:

{
  path: 'posts/:postId',
  component: PostEditor,
  meta: {
    can: function (to, from, can) {
      return axios.get(/* fetch post async */)
        .then({post} => can('delete', post))
    },
    fail: '/posts'
  }
}

Normally it would be better to prevent this route from being visited in the first place. Also the backend could perform a redirect. That said you have the option.

Default fail route

By default if you omit the 'fail' property from the a routes meta a failed check will redirect to /. You can change this behaviour by setting the option failRoute.

This is useful if you use the library in an authentication flow. E.g. by setting it to /login.

You can also use an object for more options (see guards section in docs):

failRoute: {path: '/login': replace: true}

This will use replace rather than push when redirecting to the login page.

$from

You can set the failRoute to the special value $from which will return the user to wherever they came from

Global rules

You can also use global rules in your routes.

However when running in strict mode you have to be explicit about using these in your routes.

{
  path: 'village/:villageId',
  component: Pillager,
  meta: {
    can: 'pillage'
  }
}

In strict mode:

import {GlobalRule} from 'browser-acl'
...
{
  path: 'village/:villageId',
  component: Pillager,
  meta: {
    can: `pillage ${GlobalRule}`
  }
}

See options below.

Options

assumeGlobal

default: true

When true you can use global rules in your routes without explicitly marking them as global.

Note: In strict mode this is turned of. You can override this by explicitly setting assumeGlobal to true.

acl

default: {}

Options object passed to the Acl contructor.

caseMode

default: true

Assume case means that an upper case subject is the name of a class or a constructor function and that a lower case subject is the component member name of an instance of that class.

E.g. if subject is post the directive will try to look up the data member post on the component.

If caseMode is set to false this behavior is disabled and post will be treated as a subject name.

directive

default: can

The name of the directive. E.g. can produces a directive called v-can and a helper function called $can.

You'll most likely only use this if you want to replace this module with an existing one that uses a different name.

failRoute

default: /

helper

default: true

Adds $can, $can.not, $can.some, and $can.every helper function to the Vue prototype when true.

router

default: undefined

Pass in a router instance if you want to make use of the ACL functionality in routers.

strict

default: false

When set to true a route without meta.can will automatically fail. In addition the setting will cascade to the Acl settings, making these equivalent:

Vue.use(Acl, user, acl => {...}, {strict: true}}
Vue.use(Acl, user, acl => {...}, {strict: true, acl: {strict: true}}

You can override this behavior like this:

Vue.use(Acl, user, acl => {...}, {strict: true, acl: {strict: false}}

Related

These are related projects with different approaches:

• vue-kindergarten uses a powerful sandbox pattern. Integrates with Nuxt.js
• vue-acl rather than saying what you can do you tell what the role is needed to perform an action.
• casl-vue