Connects business objects and REST web services
Clone or download
jtgrenz and jeremy use UnnamedResource when resource fails to create normally (#293)
When loading a resource, checking if the key responds to `to_sym` is
insufficient to ensure a valid resource is created. An integer like
1234 will not respond to `to_sym` but "1234" will. Attempting to
check const_defined? for :"1234" will result in a "NameError: wrong
constant name 1234"

Similarly, any string with special characters or spaces will error as

Instead, this stops checking for symbols in Base#split_options and will
catch the NameError exception should it arise and create a resource
called UnnamedResource instead which will hold the resource attributes.
Latest commit 0ae3010 Jul 10, 2018


Active Resource

Active Resource (ARes) connects business objects and Representational State Transfer (REST) web services. It implements object-relational mapping for REST web services to provide transparent proxying capabilities between a client (ActiveResource) and a RESTful service (which is provided by Simply RESTful routing in ActionController::Resources).


Active Resource attempts to provide a coherent wrapper object-relational mapping for REST web services. It follows the same philosophy as Active Record, in that one of its prime aims is to reduce the amount of code needed to map to these resources. This is made possible by relying on a number of code- and protocol-based conventions that make it easy for Active Resource to infer complex relations and structures. These conventions are outlined in detail in the documentation for ActiveResource::Base.


Model classes are mapped to remote REST resources by Active Resource much the same way Active Record maps model classes to database tables. When a request is made to a remote resource, a REST JSON request is generated, transmitted, and the result received and serialized into a usable Ruby object.

Download and installation

The latest version of Active Resource can be installed with RubyGems:

% [sudo] gem install activeresource

Or added to a Gemfile:

gem 'activeresource'

Source code can be downloaded on GitHub

Configuration and Usage

Putting Active Resource to use is very similar to Active Record. It's as simple as creating a model class that inherits from ActiveResource::Base and providing a site class variable to it:

class Person < ActiveResource::Base = ""

Now the Person class is REST enabled and can invoke REST services very similarly to how Active Record invokes life cycle methods that operate against a persistent store.

# Find a person with id = 1
tyler = Person.find(1)
Person.exists?(1)  # => true

As you can see, the methods are quite similar to Active Record's methods for dealing with database records. But rather than dealing directly with a database record, you're dealing with HTTP resources (which may or may not be database records).

Connection settings (`site`, `headers`, `user`, `password`, `proxy`) and the connections themselves are store in thread-local variables to make them thread-safe, so you can also set these dynamically, even in a multi-threaded environment, for instance: = api_site_for(request)


Active Resource supports the token based authentication provided by Rails through the ActionController::HttpAuthentication::Token class using custom headers.

class Person < ActiveResource::Base
  self.headers['Authorization'] = 'Token token="abcd"'

You can also set any specific HTTP header using the same way. As mentioned above, headers are thread-safe, so you can set headers dynamically, even in a multi-threaded environment:

ActiveResource::Base.headers['Authorization'] = current_session_api_token


Active Resource is built on a standard JSON or XML format for requesting and submitting resources over HTTP. It mirrors the RESTful routing built into Action Controller but will also work with any other REST service that properly implements the protocol. REST uses HTTP, but unlike “typical” web applications, it makes use of all the verbs available in the HTTP specification:

  • GET requests are used for finding and retrieving resources.

  • POST requests are used to create new resources.

  • PUT requests are used to update existing resources.

  • DELETE requests are used to delete resources.

For more information on how this protocol works with Active Resource, see the ActiveResource::Base documentation; for more general information on REST web services, see the article here.


Find requests use the GET method and expect the JSON form of whatever resource/resources is/are being requested. So, for a request for a single element, the JSON of that item is expected in response:

# Expects a response of
# {"id":1,"first":"Tyler","last":"Durden"}
# for GET
tyler = Person.find(1)

The JSON document that is received is used to build a new object of type Person, with each JSON element becoming an attribute on the object.

tyler.is_a? Person  # => true
tyler.last  # => 'Durden'

Any complex element (one that contains other elements) becomes its own object:

# With this response:
# {"id":1,"first":"Tyler","address":{"street":"Paper St.","state":"CA"}}
# for GET
tyler = Person.find(1)
tyler.address  # => <Person::Address::xxxxx>
tyler.address.street  # => 'Paper St.'

Collections can also be requested in a similar fashion

# Expects a response of
# [
#   {"id":1,"first":"Tyler","last":"Durden"},
#   {"id":2,"first":"Tony","last":"Stark",}
# ]
# for GET
people = Person.all
people.first  # => <Person::xxx 'first' => 'Tyler' ...>
people.last  # => <Person::xxx 'first' => 'Tony' ...>


Creating a new resource submits the JSON form of the resource as the body of the request and expects a 'Location' header in the response with the RESTful URL location of the newly created resource. The id of the newly created resource is parsed out of the Location response header and automatically set as the id of the ARes object.

# {"first":"Tyler","last":"Durden"}
# is submitted as the body on
# if include_root_in_json is not set or set to false => {"first":"Tyler"}
# if include_root_in_json is set to true => {"person":{"first":"Tyler"}}
# when save is called on a new Person object.  An empty response is
# is expected with a 'Location' header value:
# Response (201): Location:
tyler = => 'Tyler')  # => true  # => true  # => false    # => 2


'save' is also used to update an existing resource and follows the same protocol as creating a resource with the exception that no response headers are needed – just an empty response when the update on the server side was successful.

# {"first":"Tyler"}
# is submitted as the body on
# if include_root_in_json is not set or set to false => {"first":"Tyler"}
# if include_root_in_json is set to true => {"person":{"first":"Tyler"}}
# when save is called on an existing Person object.  An empty response is
# is expected with code (204)
tyler = Person.find(1)
tyler.first # => 'Tyler'
tyler.first = 'Tyson'  # => true


Destruction of a resource can be invoked as a class and instance method of the resource.

# A request is made to
# for both of these forms.  An empty response with
# is expected with response code (200)
tyler = Person.find(1)
tyler.destroy  # => true
tyler.exists?  # => false
Person.delete(2)  # => true
Person.exists?(2) # => false


Relationships between resources can be declared using the standard association syntax that should be familiar to anyone who uses activerecord. For example, using the class definition below:

class Post < ActiveResource::Base = ""
  has_many :comments

post = Post.find(1)      # issues GET
comments = post.comments # issues GET

If you control the server, you may wish to include nested resources thus avoiding a second network request. Given the resource above, if the response includes comments in the response, they will be automatically loaded into the activeresource object. The server-side model can be adjusted as follows to include comments in the response.

class Post < ActiveRecord::Base
  has_many :comments

  def as_json(options)


Active Resource instruments the event `request.active_resource` when doing a request to the remote service. You can subscribe to it by doing:

ActiveSupport::Notifications.subscribe('request.active_resource')  do |name, start, finish, id, payload|

The `payload` is a `Hash` with the following keys:

  • `method` as a `Symbol`

  • `request_uri` as a `String`

  • `result` as an `Net::HTTPResponse`


Active Resource is released under the MIT license:

Contributing to Active Resource

Active Resource is work of many contributors. You're encouraged to submit pull requests, propose features and discuss issues.



Full API documentation is available at

Bug reports and feature requests can be filed with the rest for the Ruby on Rails project here:

You can find more usage information in the ActiveResource::Base documentation.