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Source:  http://api.rubyonrails.org/classes/ActiveResource/Base.html

ActiveResource::Base is the main class for mapping RESTful resources as models in a Rails application.

For an outline of what Active Resource is capable of, see files/vendor/rails/activeresource/README.html.

Automated mapping

Active Resource objects represent your RESTful resources as manipulatable Ruby objects. To map resources to Ruby objects, Active Resource only needs a class name that corresponds to the resource name (e.g., the class Person maps to the resources people, very similarly to Active Record) and a site value, which holds the URI of the resources.

  class Person < ActiveResource::Base
    self.site = "http://api.people.com:3000/"
  end

Now the Person class is mapped to RESTful resources located at api.people.com:3000/people/, and you can now use Active Resource‘s lifecycles methods to manipulate resources. In the case where you already have an existing model with the same name as the desired RESTful resource you can set the element_name value.

  class PersonResource < ActiveResource::Base
    self.site = "http://api.people.com:3000/"
    self.element_name = "person"
  end

Lifecycle methods

Active Resource exposes methods for creating, finding, updating, and deleting resources from REST web services.

  ryan = Person.new(:first => 'Ryan', :last => 'Daigle')
  ryan.save                # => true
  ryan.id                  # => 2
  Person.exists?(ryan.id)  # => true
  ryan.exists?             # => true

  ryan = Person.find(1)
  # Resource holding our newly created Person object

  ryan.first = 'Rizzle'
  ryan.save                # => true

  ryan.destroy             # => true

As you can see, these are very similar to Active Record‘s lifecycle methods for database records. You can read more about each of these methods in their respective documentation.

Custom REST methods

Since simple CRUD/lifecycle methods can‘t accomplish every task, Active Resource also supports defining your own custom REST methods. To invoke them, Active Resource provides the get, post, put and delete methods where you can specify a custom REST method name to invoke.

  # POST to the custom 'register' REST method, i.e. POST /people/new/register.xml.
  Person.new(:name => 'Ryan').post(:register)
  # => { :id => 1, :name => 'Ryan', :position => 'Clerk' }

  # PUT an update by invoking the 'promote' REST method, i.e. PUT /people/1/promote.xml?position=Manager.
  Person.find(1).put(:promote, :position => 'Manager')
  # => { :id => 1, :name => 'Ryan', :position => 'Manager' }

  # GET all the positions available, i.e. GET /people/positions.xml.
  Person.get(:positions)
  # => [{:name => 'Manager'}, {:name => 'Clerk'}]

  # DELETE to 'fire' a person, i.e. DELETE /people/1/fire.xml.
  Person.find(1).delete(:fire)

For more information on using custom REST methods, see the ActiveResource::CustomMethods documentation.

Validations

You can validate resources client side by overriding validation methods in the base class.

  class Person < ActiveResource::Base
     self.site = "http://api.people.com:3000/"
     protected
       def validate
         errors.add("last", "has invalid characters") unless last =~ /[a-zA-Z]*/
       end
  end

See the ActiveResource::Validations documentation for more information.

Authentication

Many REST APIs will require authentication, usually in the form of basic HTTP authentication. Authentication can be specified by:

  • putting the credentials in the URL for the site variable.
     class Person < ActiveResource::Base
       self.site = "http://ryan:password@api.people.com:3000/"
     end
    
  • defining user and/or password variables
     class Person < ActiveResource::Base
       self.site = "http://api.people.com:3000/"
       self.user = "ryan"
       self.password = "password"
     end
    

For obvious security reasons, it is probably best if such services are available over HTTPS.

Note: Some values cannot be provided in the URL passed to site. e.g. email addresses as usernames. In those situations you should use the seperate user and password option.

Errors & Validation

Error handling and validation is handled in much the same manner as you‘re used to seeing in Active Record. Both the response code in the HTTP response and the body of the response are used to indicate that an error occurred.

Resource errors

When a GET is requested for a resource that does not exist, the HTTP 404 (Resource Not Found) response code will be returned from the server which will raise an ActiveResource::ResourceNotFound exception.

  # GET http://api.people.com:3000/people/999.xml
  ryan = Person.find(999) # 404, raises ActiveResource::ResourceNotFound

404 is just one of the HTTP error response codes that Active Resource will handle with its own exception. The following HTTP response codes will also result in these exceptions:

These custom exceptions allow you to deal with resource errors more naturally and with more precision rather than returning a general HTTP error. For example:

  begin
    ryan = Person.find(my_id)
  rescue ActiveResource::ResourceNotFound
    redirect_to :action => 'not_found'
  rescue ActiveResource::ResourceConflict, ActiveResource::ResourceInvalid
    redirect_to :action => 'new'
  end

Validation errors

Active Resource supports validations on resources and will return errors if any these validations fail (e.g., "First name can not be blank" and so on). These types of errors are denoted in the response by a response code of 422 and an XML representation of the validation errors. The save operation will then fail (with a false return value) and the validation errors can be accessed on the resource in question.

  ryan = Person.find(1)
  ryan.first # => ''
  ryan.save  # => false

  # When
  # PUT http://api.people.com:3000/people/1.xml
  # is requested with invalid values, the response is:
  #
  # Response (422):
  # <errors type="array"><error>First cannot be empty</error></errors>
  #

  ryan.errors.invalid?(:first)  # => true
  ryan.errors.full_messages     # => ['First cannot be empty']

Learn more about Active Resource‘s validation features in the ActiveResource::Validations documentation.

Timeouts

Active Resource relies on HTTP to access RESTful APIs and as such is inherently susceptible to slow or unresponsive servers. In such cases, your Active Resource method calls could timeout. You can control the amount of time before Active Resource times out with the timeout variable.

  class Person < ActiveResource::Base
    self.site = "http://api.people.com:3000/"
    self.timeout = 5
  end

This sets the timeout to 5 seconds. You can adjust the timeout to a value suitable for the RESTful API you are accessing. It is recommended to set this to a reasonably low value to allow your Active Resource clients (especially if you are using Active Resource in a Rails application) to fail-fast (see en.wikipedia.org/wiki/Fail-fast) rather than cause cascading failures that could incapacitate your server.

When a timeout occurs, an ActiveResource::TimeoutError is raised. You should rescue from ActiveResource::TimeoutError in your Active Resource method calls.

Internally, Active Resource relies on Ruby‘s Net::HTTP library to make HTTP requests. Setting timeout sets the read_timeout of the internal Net::HTTP instance to the same value. The default read_timeout is 60 seconds on most Ruby implementations.

Methods
Public Class methods
collection_path(prefix_options = {}, query_options = nil)

Gets the collection path for the REST resources. If the query_options parameter is omitted, Rails will split from the prefix_options.

Options

  • prefix_options - A hash to add a prefix to the request for nested URL‘s (e.g., :account_id => 19 would yield a URL like /accounts/19/purchases.xml).
  • query_options - A hash to add items to the query string for the request.

Examples

  Post.collection_path
  # => /posts.xml

  Comment.collection_path(:post_id => 5)
  # => /posts/5/comments.xml

  Comment.collection_path(:post_id => 5, :active => 1)
  # => /posts/5/comments.xml?active=1

  Comment.collection_path({:post_id => 5}, {:active => 1})
  # => /posts/5/comments.xml?active=1
     # File activeresource/lib/active_resource/base.rb, line 423
423:       def collection_path(prefix_options = {}, query_options = nil)
424:         prefix_options, query_options = split_options(prefix_options) if query_options.nil?
425:         "#{prefix(prefix_options)}#{collection_name}.#{format.extension}#{query_string(query_options)}"
426:       end
connection(refresh = false)

An instance of ActiveResource::Connection that is the base connection to the remote service. The refresh parameter toggles whether or not the connection is refreshed at every request or not (defaults to false).

     # File activeresource/lib/active_resource/base.rb, line 313
313:       def connection(refresh = false)
314:         if defined?(@connection) || superclass == Object
315:           @connection = Connection.new(site, format) if refresh || @connection.nil?
316:           @connection.user = user if user
317:           @connection.password = password if password
318:           @connection.timeout = timeout if timeout
319:           @connection
320:         else
321:           superclass.connection
322:         end
323:       end
create(attributes = {})

Create a new resource instance and request to the remote service that it be saved, making it equivalent to the following simultaneous calls:

  ryan = Person.new(:first => 'ryan')
  ryan.save

The newly created resource is returned. If a failure has occurred an exception will be raised (see save). If the resource is invalid and has not been saved then valid? will return false, while new? will still return true.

Examples

  Person.create(:name => 'Jeremy', :email => 'myname@nospam.com', :enabled => true)
  my_person = Person.find(:first)
  my_person.email # => myname@nospam.com

  dhh = Person.create(:name => 'David', :email => 'dhh@nospam.com', :enabled => true)
  dhh.valid? # => true
  dhh.new?   # => false

  # We'll assume that there's a validation that requires the name attribute
  that_guy = Person.create(:name => '', :email => 'thatguy@nospam.com', :enabled => true)
  that_guy.valid? # => false
  that_guy.new?   # => true
     # File activeresource/lib/active_resource/base.rb, line 454
454:       def create(attributes = {})
455:         returning(self.new(attributes)) { |res| res.save }        
456:       end
delete(id, options = {})

Deletes the resources with the ID in the id parameter.

Options

All options specify prefix and query parameters.

Examples

  Event.delete(2) # sends DELETE /events/2

  Event.create(:name => 'Free Concert', :location => 'Community Center')
  my_event = Event.find(:first) # let's assume this is event with ID 7
  Event.delete(my_event.id) # sends DELETE /events/7

  # Let's assume a request to events/5/cancel.xml
  Event.delete(params[:id]) # sends DELETE /events/5
     # File activeresource/lib/active_resource/base.rb, line 526
526:       def delete(id, options = {})
527:         connection.delete(element_path(id, options))
528:       end
element_path(id, prefix_options = {}, query_options = nil)

Gets the element path for the given ID in id. If the query_options parameter is omitted, Rails will split from the prefix options.

Options

prefix_options - A hash to add a prefix to the request for nested URLs (e.g., :account_id => 19

                   would yield a URL like <tt>/accounts/19/purchases.xml</tt>).

query_options - A hash to add items to the query string for the request.

Examples

  Post.element_path(1)
  # => /posts/1.xml

  Comment.element_path(1, :post_id => 5)
  # => /posts/5/comments/1.xml

  Comment.element_path(1, :post_id => 5, :active => 1)
  # => /posts/5/comments/1.xml?active=1

  Comment.element_path(1, {:post_id => 5}, {:active => 1})
  # => /posts/5/comments/1.xml?active=1
     # File activeresource/lib/active_resource/base.rb, line 397
397:       def element_path(id, prefix_options = {}, query_options = nil)
398:         prefix_options, query_options = split_options(prefix_options) if query_options.nil?
399:         "#{prefix(prefix_options)}#{collection_name}/#{id}.#{format.extension}#{query_string(query_options)}"        
400:       end
exists?(id, options = {})

Asserts the existence of a resource, returning true if the resource is found.

Examples

  Note.create(:title => 'Hello, world.', :body => 'Nothing more for now...')
  Note.exists?(1) # => true

  Note.exists(1349) # => false
     # File activeresource/lib/active_resource/base.rb, line 537
537:       def exists?(id, options = {})
538:         if id
539:           prefix_options, query_options = split_options(options[:params])
540:           path = element_path(id, prefix_options, query_options)
541:           response = connection.head(path, headers)
542:           response.code.to_i == 200
543:         end
544:         # id && !find_single(id, options).nil?
545:       rescue ActiveResource::ResourceNotFound
546:         false
547:       end
find(*arguments)

Core method for finding resources. Used similarly to Active Record‘s find method.

Arguments

The first argument is considered to be the scope of the query. That is, how many resources are returned from the request. It can be one of the following.

  • :one - Returns a single resource.
  • :first - Returns the first resource found.
  • :all - Returns every resource that matches the request.

Options

  • :from - Sets the path or custom method that resources will be fetched from.
  • :params - Sets query and prefix (nested URL) parameters.

Examples

  Person.find(1)
  # => GET /people/1.xml

  Person.find(:all)
  # => GET /people.xml

  Person.find(:all, :params => { :title => "CEO" })
  # => GET /people.xml?title=CEO

  Person.find(:first, :from => :managers)
  # => GET /people/managers.xml

  Person.find(:all, :from => "/companies/1/people.xml")
  # => GET /companies/1/people.xml

  Person.find(:one, :from => :leader)
  # => GET /people/leader.xml

  Person.find(:all, :from => :developers, :params => { :language => 'ruby' })
  # => GET /people/developers.xml?language=ruby

  Person.find(:one, :from => "/companies/1/manager.xml")
  # => GET /companies/1/manager.xml

  StreetAddress.find(1, :params => { :person_id => 1 })
  # => GET /people/1/street_addresses/1.xml
     # File activeresource/lib/active_resource/base.rb, line 500
500:       def find(*arguments)
501:         scope   = arguments.slice!(0)
502:         options = arguments.slice!(0) || {}
503: 
504:         case scope
505:           when :all   then find_every(options)
506:           when :first then find_every(options).first
507:           when :one   then find_one(options)
508:           else             find_single(scope, options)
509:         end
510:       end
format=(mime_type_reference_or_format)

Sets the format that attributes are sent and received in from a mime type reference:

  Person.format = :json
  Person.find(1) # => GET /people/1.json

  Person.format = ActiveResource::Formats::XmlFormat
  Person.find(1) # => GET /people/1.xml

Default format is :xml.

     # File activeresource/lib/active_resource/base.rb, line 282
282:       def format=(mime_type_reference_or_format)
283:         format = mime_type_reference_or_format.is_a?(Symbol) ? 
284:           ActiveResource::Formats[mime_type_reference_or_format] : mime_type_reference_or_format
285: 
286:         write_inheritable_attribute("format", format)
287:         connection.format = format if site
288:       end
headers()
     # File activeresource/lib/active_resource/base.rb, line 325
325:       def headers
326:         @headers ||= {}
327:       end
new(attributes = {})

Constructor method for new resources; the optional attributes parameter takes a hash of attributes for the new resource.

Examples

  my_course = Course.new
  my_course.name = "Western Civilization"
  my_course.lecturer = "Don Trotter"
  my_course.save

  my_other_course = Course.new(:name => "Philosophy: Reason and Being", :lecturer => "Ralph Cling")
  my_other_course.save
     # File activeresource/lib/active_resource/base.rb, line 637
637:     def initialize(attributes = {})
638:       @attributes     = {}
639:       @prefix_options = {}
640:       load(attributes)
641:     end
password()

Gets the password for REST HTTP authentication.

     # File activeresource/lib/active_resource/base.rb, line 258
258:       def password
259:         # Not using superclass_delegating_reader. See +site+ for explanation
260:         if defined?(@password)
261:           @password
262:         elsif superclass != Object && superclass.password
263:           superclass.password.dup.freeze
264:         end
265:       end
password=(password)

Sets the password for REST HTTP authentication.

     # File activeresource/lib/active_resource/base.rb, line 268
268:       def password=(password)
269:         @connection = nil
270:         @password = password
271:       end
prefix(options={})

Gets the prefix for a resource‘s nested URL (e.g., prefix/collectionname/1.xml) This method is regenerated at runtime based on what the prefix is set to.

     # File activeresource/lib/active_resource/base.rb, line 338
338:       def prefix(options={})
339:         default = site.path
340:         default << '/' unless default[-1..-1] == '/'
341:         # generate the actual method based on the current site path
342:         self.prefix = default
343:         prefix(options)
344:       end
prefix=(value = '/')

Sets the prefix for a resource‘s nested URL (e.g., prefix/collectionname/1.xml). Default value is site.path.

     # File activeresource/lib/active_resource/base.rb, line 355
355:       def prefix=(value = '/')
356:         # Replace :placeholders with '#{embedded options[:lookups]}'
357:         prefix_call = value.gsub(/:\w+/) { |key| "\#{options[#{key}]}" }
358: 
359:         # Redefine the new methods.
360:         code = "def prefix_source() \"\#{value}\" end\ndef prefix(options={}) \"\#{prefix_call}\" end\n"
361:         silence_warnings { instance_eval code, __FILE__, __LINE__ }
362:       rescue
363:         logger.error "Couldn't set prefix: #{$!}\n  #{code}"
364:         raise
365:       end
prefix_source()

An attribute reader for the source string for the resource path prefix. This method is regenerated at runtime based on what the prefix is set to.

     # File activeresource/lib/active_resource/base.rb, line 348
348:       def prefix_source
349:         prefix # generate #prefix and #prefix_source methods first
350:         prefix_source
351:       end
site()

Gets the URI of the REST resources to map for this class. The site variable is required Active Resource‘s mapping to work.

     # File activeresource/lib/active_resource/base.rb, line 205
205:       def site
206:         # Not using superclass_delegating_reader because don't want subclasses to modify superclass instance
207:         #
208:         # With superclass_delegating_reader
209:         #
210:         #   Parent.site = 'http://anonymous@test.com'
211:         #   Subclass.site # => 'http://anonymous@test.com'
212:         #   Subclass.site.user = 'david'
213:         #   Parent.site # => 'http://david@test.com'
214:         #
215:         # Without superclass_delegating_reader (expected behaviour)
216:         #
217:         #   Parent.site = 'http://anonymous@test.com'
218:         #   Subclass.site # => 'http://anonymous@test.com'
219:         #   Subclass.site.user = 'david' # => TypeError: can't modify frozen object
220:         #
221:         if defined?(@site)
222:           @site
223:         elsif superclass != Object && superclass.site
224:           superclass.site.dup.freeze
225:         end
226:       end
site=(site)

Sets the URI of the REST resources to map for this class to the value in the site argument. The site variable is required Active Resource‘s mapping to work.

     # File activeresource/lib/active_resource/base.rb, line 230
230:       def site=(site)
231:         @connection = nil
232:         if site.nil?
233:           @site = nil
234:         else
235:           @site = create_site_uri_from(site)
236:           @user = URI.decode(@site.user) if @site.user
237:           @password = URI.decode(@site.password) if @site.password
238:         end
239:       end
timeout()

Gets tthe number of seconds after which requests to the REST API should time out.

     # File activeresource/lib/active_resource/base.rb, line 302
302:       def timeout
303:         if defined?(@timeout)
304:           @timeout
305:         elsif superclass != Object && superclass.timeout
306:           superclass.timeout
307:         end
308:       end
timeout=(timeout)

Sets the number of seconds after which requests to the REST API should time out.

     # File activeresource/lib/active_resource/base.rb, line 296
296:       def timeout=(timeout)
297:         @connection = nil
298:         @timeout = timeout
299:       end
user()

Gets the user for REST HTTP authentication.

     # File activeresource/lib/active_resource/base.rb, line 242
242:       def user
243:         # Not using superclass_delegating_reader. See +site+ for explanation
244:         if defined?(@user)
245:           @user
246:         elsif superclass != Object && superclass.user
247:           superclass.user.dup.freeze
248:         end
249:       end
user=(user)

Sets the user for REST HTTP authentication.

     # File activeresource/lib/active_resource/base.rb, line 252
252:       def user=(user)
253:         @connection = nil
254:         @user = user
255:       end
Public Instance methods
==(other)

Test for equality. Resource are equal if and only if other is the same object or is an instance of the same class, is not new?, and has the same id.

Examples

  ryan = Person.create(:name => 'Ryan')
  jamie = Person.create(:name => 'Jamie')

  ryan == jamie
  # => false (Different name attribute and id)

  ryan_again = Person.new(:name => 'Ryan')
  ryan == ryan_again
  # => false (ryan_again is new?)

  ryans_clone = Person.create(:name => 'Ryan')
  ryan == ryans_clone
  # => false (Different id attributes)

  ryans_twin = Person.find(ryan.id)
  ryan == ryans_twin
  # => true
     # File activeresource/lib/active_resource/base.rb, line 732
732:     def ==(other)
733:       other.equal?(self) || (other.instance_of?(self.class) && !other.new? && other.id == id)
734:     end
clone()

Returns a clone of the resource that hasn‘t been assigned an id yet and is treated as a new resource.

  ryan = Person.find(1)
  not_ryan = ryan.clone
  not_ryan.new?  # => true

Any active resource member attributes will NOT be cloned, though all other attributes are. This is to prevent the conflict between any prefix_options that refer to the original parent resource and the newly cloned parent resource that does not exist.

  ryan = Person.find(1)
  ryan.address = StreetAddress.find(1, :person_id => ryan.id)
  ryan.hash = {:not => "an ARes instance"}

  not_ryan = ryan.clone
  not_ryan.new?            # => true
  not_ryan.address         # => NoMethodError
  not_ryan.hash            # => {:not => "an ARes instance"}
     # File activeresource/lib/active_resource/base.rb, line 663
663:     def clone
664:       # Clone all attributes except the pk and any nested ARes
665:       cloned = attributes.reject {|k,v| k == self.class.primary_key || v.is_a?(ActiveResource::Base)}.inject({}) do |attrs, (k, v)|
666:         attrs[k] = v.clone
667:         attrs
668:       end
669:       # Form the new resource - bypass initialize of resource with 'new' as that will call 'load' which
670:       # attempts to convert hashes into member objects and arrays into collections of objects.  We want
671:       # the raw objects to be cloned so we bypass load by directly setting the attributes hash.
672:       resource = self.class.new({})
673:       resource.prefix_options = self.prefix_options
674:       resource.send :instance_variable_set, '@attributes', cloned
675:       resource
676:     end
destroy()

Deletes the resource from the remote service.

Examples

  my_id = 3
  my_person = Person.find(my_id)
  my_person.destroy
  Person.find(my_id) # 404 (Resource Not Found)

  new_person = Person.create(:name => 'James')
  new_id = new_person.id # => 7
  new_person.destroy
  Person.find(new_id) # 404 (Resource Not Found)
     # File activeresource/lib/active_resource/base.rb, line 795
795:     def destroy
796:       connection.delete(element_path, self.class.headers)
797:     end
dup()

Duplicate the current resource without saving it.

Examples

  my_invoice = Invoice.create(:customer => 'That Company')
  next_invoice = my_invoice.dup
  next_invoice.new? # => true

  next_invoice.save
  next_invoice == my_invoice # => false (different id attributes)

  my_invoice.customer   # => That Company
  next_invoice.customer # => That Company
     # File activeresource/lib/active_resource/base.rb, line 759
759:     def dup
760:       returning self.class.new do |resource|
761:         resource.attributes     = @attributes
762:         resource.prefix_options = @prefix_options
763:       end
764:     end
eql?(other)

Tests for equality (delegates to ==).

     # File activeresource/lib/active_resource/base.rb, line 737
737:     def eql?(other)
738:       self == other
739:     end
exists?()

Evaluates to true if this resource is not new? and is found on the remote service. Using this method, you can check for resources that may have been deleted between the object‘s instantiation and actions on it.

Examples

  Person.create(:name => 'Theodore Roosevelt')
  that_guy = Person.find(:first)
  that_guy.exists? # => true

  that_lady = Person.new(:name => 'Paul Bean')
  that_lady.exists? # => false

  guys_id = that_guy.id
  Person.delete(guys_id)
  that_guy.exists? # => false
     # File activeresource/lib/active_resource/base.rb, line 815
815:     def exists?
816:       !new? && self.class.exists?(to_param, :params => prefix_options)      
817:     end
hash()

Delegates to id in order to allow two resources of the same type and id to work with something like:

  [Person.find(1), Person.find(2)] & [Person.find(1), Person.find(4)] # => [Person.find(1)]
     # File activeresource/lib/active_resource/base.rb, line 743
743:     def hash
744:       id.hash
745:     end
id()

Get the id attribute of the resource.

     # File activeresource/lib/active_resource/base.rb, line 696
696:     def id
697:       attributes[self.class.primary_key]
698:     end
id=(id)

Set the id attribute of the resource.

     # File activeresource/lib/active_resource/base.rb, line 701
701:     def id=(id)
702:       attributes[self.class.primary_key] = id
703:     end
load(attributes)

A method to manually load attributes from a hash. Recursively loads collections of resources. This method is called in initialize and create when a hash of attributes is provided.

Examples

  my_attrs = {:name => 'J&J Textiles', :industry => 'Cloth and textiles'}

  the_supplier = Supplier.find(:first)
  the_supplier.name # => 'J&M Textiles'
  the_supplier.load(my_attrs)
  the_supplier.name('J&J Textiles')

  # These two calls are the same as Supplier.new(my_attrs)
  my_supplier = Supplier.new
  my_supplier.load(my_attrs)

  # These three calls are the same as Supplier.create(my_attrs)
  your_supplier = Supplier.new
  your_supplier.load(my_attrs)
  your_supplier.save
     # File activeresource/lib/active_resource/base.rb, line 883
883:     def load(attributes)
884:       raise ArgumentError, "expected an attributes Hash, got #{attributes.inspect}" unless attributes.is_a?(Hash)
885:       @prefix_options, attributes = split_options(attributes)
886:       attributes.each do |key, value|
887:         @attributes[key.to_s] =
888:           case value
889:             when Array
890:               resource = find_or_create_resource_for_collection(key)
891:               value.map { |attrs| resource.new(attrs) }
892:             when Hash
893:               resource = find_or_create_resource_for(key)
894:               resource.new(value)
895:             else
896:               value.dup rescue value
897:           end
898:       end
899:       self
900:     end
new?()

A method to determine if the resource a new object (i.e., it has not been POSTed to the remote service yet).

Examples

  not_new = Computer.create(:brand => 'Apple', :make => 'MacBook', :vendor => 'MacMall')
  not_new.new? # => false

  is_new = Computer.new(:brand => 'IBM', :make => 'Thinkpad', :vendor => 'IBM')
  is_new.new? # => true

  is_new.save
  is_new.new? # => false
     # File activeresource/lib/active_resource/base.rb, line 691
691:     def new?
692:       id.nil?
693:     end
reload()

A method to reload the attributes of this object from the remote web service.

Examples

  my_branch = Branch.find(:first)
  my_branch.name # => "Wislon Raod"

  # Another client fixes the typo...

  my_branch.name # => "Wislon Raod"
  my_branch.reload
  my_branch.name # => "Wilson Road"
     # File activeresource/lib/active_resource/base.rb, line 859
859:     def reload
860:       self.load(self.class.find(to_param, :params => @prefix_options).attributes)
861:     end
respond_to?(method, include_priv = false)

A method to determine if an object responds to a message (e.g., a method call). In Active Resource, a Person object with a name attribute can answer true to my_person.respond_to?("name"), my_person.respond_to?("name="), and my_person.respond_to?("name?").

     # File activeresource/lib/active_resource/base.rb, line 908
908:     def respond_to?(method, include_priv = false)
909:       method_name = method.to_s
910:       if attributes.nil?
911:         return super
912:       elsif attributes.has_key?(method_name)
913:         return true 
914:       elsif ['?','='].include?(method_name.last) && attributes.has_key?(method_name.first(-1))
915:         return true
916:       end
917:       # super must be called at the end of the method, because the inherited respond_to?
918:       # would return true for generated readers, even if the attribute wasn't present
919:       super
920:     end
save()

A method to save (POST) or update (PUT) a resource. It delegates to create if a new object, update if it is existing. If the response to the save includes a body, it will be assumed that this body is XML for the final object as it looked after the save (which would include attributes like created_at that weren‘t part of the original submit).

Examples

  my_company = Company.new(:name => 'RoleModel Software', :owner => 'Ken Auer', :size => 2)
  my_company.new? # => true
  my_company.save # sends POST /companies/ (create)

  my_company.new? # => false
  my_company.size = 10
  my_company.save # sends PUT /companies/1 (update)
     # File activeresource/lib/active_resource/base.rb, line 779
779:     def save
780:       new? ? create : update
781:     end
to_param()

Allows Active Resource objects to be used as parameters in Action Pack URL generation.

     # File activeresource/lib/active_resource/base.rb, line 706
706:     def to_param
707:       id && id.to_s
708:     end
to_xml(options={})

A method to convert the the resource to an XML string.

Options

The options parameter is handed off to the to_xml method on each attribute, so it has the same options as the to_xml methods in Active Support.

  • :indent - Set the indent level for the XML output (default is +2+).
  • :dasherize - Boolean option to determine whether or not element names should replace underscores with dashes (default is false).
  • :skip_instruct - Toggle skipping the +instruct!+ call on the XML builder that generates the XML declaration (default is false).

Examples

  my_group = SubsidiaryGroup.find(:first)
  my_group.to_xml
  # => <?xml version="1.0" encoding="UTF-8"?>
  #    <subsidiary_group> [...] </subsidiary_group>

  my_group.to_xml(:dasherize => true)
  # => <?xml version="1.0" encoding="UTF-8"?>
  #    <subsidiary-group> [...] </subsidiary-group>

  my_group.to_xml(:skip_instruct => true)
  # => <subsidiary_group> [...] </subsidiary_group>
     # File activeresource/lib/active_resource/base.rb, line 844
844:     def to_xml(options={})
845:       attributes.to_xml({:root => self.class.element_name}.merge(options))
846:     end
Protected Instance methods
collection_path(options = nil)
     # File activeresource/lib/active_resource/base.rb, line 958
958:       def collection_path(options = nil)
959:         self.class.collection_path(options || prefix_options)
960:       end
connection(refresh = false)
     # File activeresource/lib/active_resource/base.rb, line 924
924:       def connection(refresh = false)
925:         self.class.connection(refresh)
926:       end
create()

Create (i.e., save to the remote service) the new resource.

     # File activeresource/lib/active_resource/base.rb, line 936
936:       def create
937:         returning connection.post(collection_path, to_xml, self.class.headers) do |response|
938:           self.id = id_from_response(response)
939:           load_attributes_from_response(response)
940:         end
941:       end
element_path(options = nil)
     # File activeresource/lib/active_resource/base.rb, line 954
954:       def element_path(options = nil)
955:         self.class.element_path(to_param, options || prefix_options)
956:       end
id_from_response(response)

Takes a response from a typical create post and pulls the ID out

     # File activeresource/lib/active_resource/base.rb, line 950
950:       def id_from_response(response)
951:         response['Location'][/\/([^\/]*?)(\.\w+)?$/, 1]
952:       end
load_attributes_from_response(response)
     # File activeresource/lib/active_resource/base.rb, line 943
943:       def load_attributes_from_response(response)
944:         if response['Content-Length'] != "0" && response.body.strip.size > 0
945:           load(self.class.format.decode(response.body))
946:         end
947:       end
update()

Update the resource on the remote service.

     # File activeresource/lib/active_resource/base.rb, line 929
929:       def update
930:         returning connection.put(element_path(prefix_options), to_xml, self.class.headers) do |response|
931:           load_attributes_from_response(response)
932:         end
933:       end