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A simple schema/attributes library built on top of modern JavaScript
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A simple schema/attributes library built on top of modern JavaScript

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Structure provides a simple interface which allows you to add attributes to your ES6 classes based on a schema, with validations and type coercion.

Use cases

You can use Structure for a lot of different cases, including:

  • Domain entities and value objects
  • Model business rules
  • Validation and coercion of request data
  • Map pure objects and JSON to your application classes
  • Add attributes to classes that you can't change the class hierarchy

Structure was inspired by Ruby's Virtus.

What Structure is not:

  • It's not a database abstraction
  • It's not a MVC framework (but it can be used to domain entities)
  • It's not an attempt to simulate classic inheritance in JavaScript

Getting started

npm install --save structure


For each attribute on your schema, a getter and a setter will be created into the given class. It'll also auto-assign those attributes passed to the constructor.

const { attributes } = require('structure');

const User = attributes({
  name: String,
  age: {
    type: Number,
    default: 18
  birthday: Date
})(class User {
  greet() {
    return `Hello ${}`;

/* The attributes "wraps" the Class, still providing access to its methods: */

const user = new User({
  name: 'John Foo'
});; // 'John Foo'
user.greet(); // 'Hello John Foo'

Support and compatibility

Structure is built on top of modern JavaScript, using new features like Proxy, Reflect and Symbol. That being so, there are some things regarding compatibility you should consider when using Structure.


Node only implemented all the used features on version 6, so for using Structure for a backend application you'll need Node 6 or later.


Not all major browsers implemented the used features so you'll need to transpile the code for using it. For browser usage we have the UMD version bundled with Webpack. We don't bundle Structure with its dependencies so you'll have to provide it with your module bundler. It's recommended to replace joi with joi-browser when using it on the front-end, here's how we run our test suite on the browser regarding bundling and polyfill of features.

Be aware that not the whole test suite will pass on browsers, there are some cases that can't be simulated through polyfilling, like extending Array or having a non-structure class extending a structure class. You can setup the project on your computer and run npm run test:browser to see how it'll work.

Right now 95.5% of the tests will pass on Chrome 55, and 95% will pass on Firefox 45. We intend to make it support older versions using polyfills in the next releases.

BattleCry generators

There are configurable BattleCry generators ready to be downloaded and help scaffolding schema:

npm install -g battlecry
cry download generator talyssonoc/structure
cry g schema user name age:int:required cars:string[] favoriteBook:book friends:user[]:default :updateAge

Run cry --help to check more info about the generators available;



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