siren-client

A specialized siren API client.

Usage

This particular client is built in a very specialized fashion. It operates by only working with a single entity at a time, more or less as a stream.

This makes it more suitable for use in applications that are going to make use entirely of a hypermedia-driven interface. (rather than as an ad-hoc client)

As such, it does not work with callbacks. Instead, the client instance is an emitter that emits events when a new entity is fetched. (or when an action is successfully complete)

var Siren = require('siren-client');
var client = new Siren();
 
client.on('error', function (err) {
  // these are HTTP errors, not application errors
  console.error(err);
});
 
client.on('entity', function (entity) {
  // an `Entity` instance, see docs below
  console.log(entity);
});
 
// retrieves the given url as the entry point for the api you are working with.
client.get('http://siren.example.com/');

API

Client(href) (constructor)

Creates a new client instance, if href is passed, it will use that as the entry point and starts navigating. (make sure to attach to the entity and error events)

Client#get(url, [callback])

This is how you set the entry point for the API you are interacting with. It will fetch the given URL and use that as the first/new entity.

If callback is provided, it will be invoked before either error or entity is emitted.

Client#follow(link, [callback])

This follows the given link and uses the response as the next entity.

The link param can either be a String url, or a link Object given by a siren API.

If callback is provided, it will be invoked before either error or entity is emitted.

Client#submit(action, data, [callback])

Submits the action with accompanying data to the API.

The action param is the action Object given by a siren API.

The data param is an object of key-value pairs that should be serialized and sent as the body. The easiest way to accomplish this is to use a well-formed HTML <form> along with something like form-serialize to generate the object.

If callback is provided, it will be invoked before either error or entity is emitted.

Client: entity(entity, href) (event)

Fired after an entity has been loaded. (also after an action has been processed successfully) The passed entity is an instance of Entity. (API documented below)

Client: error(err, href) (event)

Fired for errors that happen trying to send/receive data. The raw err is passed so you can respond accordingly.

NOTE: Generally, these are not application errors. These will likely be HTTP failures, rejected cross-origin requests, etc. However, a non-siren response will also emit this error. (in case your server has not started responding with siren for a specific route)

Entity(data) (constructor)

Wrapper for siren entity objects, which offers convenient APIs for finding links/entities/actions within the larger entity.

Entity#title()

Retrieves the title attribute for the entity. If not defined, it will return an empty string.

Entity#properties()

Retrieves a copy of the properties object. If none were defined, it will simply return an empty object.

Entity#class()

Retrieves a copy of the class array. This always returns an Array, even if that means it is empty.

Entity#rel()

Retrieves a copy of the rel array. (used for sub-entities) This always returns an Array, even if that means it is empty.

Entity#entity([search])

Retrieves the first entity (wrapped as an Entity instance) that matches the optional search criteria. The search parameter can be specified as:

• a String used to search for entity with a matching rel
• an Object with either a rel or class key to match against
• a Function that should return true for the correct entity

If none is found, this will return null.

Entity#entities([search])

Retrieves an Array of entities (wrapped as Entity instances) that match the optional search criteria. The search parameter can be specified as:

• a String used to search for entity with a matching rel
• an Object with either a rel or class key to match against
• a Function that should return true for the correct entity

This will return an Array, containing all the matching actions. (even if that means it is empty)

Entity#link([search])

Retrieves the first link that matches the optional search criteria. The search parameter can be specified as:

• a String used to search for link with a matching rel
• an Object with either a rel or class key to match against
• a Function that should return true for the correct link

If none is found, this will return null.

Entity#links([search])

Retrieves an Array of links that match the optional search criteria. The search parameter can be specified as:

• a String used to search for link with a matching rel
• an Object with either a rel or class key to match against
• a Function that should return true for the correct link

This will return an Array, containing all the matching links. (even if that means it is empty)

Entity#action([search])

Retrieves the first action that matches the optional search criteria. The search parameter can be specified as:

• a String used to search for action with a matching name
• an Object with either a name or class key to match against
• a Function that should return true for the correct action

If none is found, this will return null.

Entity#actions([search])

Retrieves an Array of actions that match the optional search criteria. The search parameter can be specified as:

• a String used to search for action with the same name
• an Object with either a name or class key to match against
• a Function that should return true for the correct action

This will return an Array, containing all the matching actions. (even if that means it is empty)