Mega documentation patches. #7025, #7069 [rwdaigle]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@5962 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

7 files changed, 336 insertions, 25 deletions

diff --git a/activeresource/CHANGELOG b/activeresource/CHANGELOG
index 44108fb8ce..1f30c14f6f 100644
--- a/activeresource/CHANGELOG
+++ b/activeresource/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Mega documentation patches. #7025, #7069 [rwdaigle]
+
 * Base.exists?(id, options) and Base#exists? check whether the resource is found.  #6970 [rwdaigle]
 
 * Query string support.  [untext, Jeremy Kemper]
diff --git a/activeresource/README b/activeresource/README
index f1013b54e0..a657e3a471 100644
--- a/activeresource/README
+++ b/activeresource/README
@@ -1 +1,230 @@
-= Active Resource -- Object-oriented REST services
\ No newline at end of file
+= Active Resource -- Object-oriented REST services
+
+Active Resource (ARes) connects business objects and REST web services.  It is a library
+intended to provide transparent proxying capabilities between a client and a RESTful
+service (for which Rails provides the {Simply RESTful routing}[http://dev.rubyonrails.org/browser/trunk/actionpack/lib/action_controller/resources.rb] implementation).
+
+=== Configuration & Usage
+
+Configuration is as simple as inheriting from ActiveResource::Base and providing a site
+class variable:
+
+   class Person < ActiveResource::Base
+     self.site = "http://api.people.com:3000/"
+   end
+
+Person is now REST enable and can invoke REST services very similarly to how ActiveRecord invokes
+lifecycle methods that operate against a persistent store.
+
+   # Find a person with id = 1
+   # This will invoke the following Http call:
+   # GET http://api.people.com:3000/people/1.xml
+   # and will load up the XML response into a new
+   # Person object
+   #
+   ryan = Person.find(1)
+   Person.exists?(1)  #=> true
+
+   # To create a new person - instantiate the object and call 'save',
+   # which will invoke this Http call:
+   # POST http://api.people.com:3000/people.xml
+   # (and will submit the XML format of the person object in the request)
+   #
+   ryan = Person.new(:first => 'Ryan', :last => 'Daigle')
+   ryan.save  #=> true
+   ryan.id  #=> 2
+   Person.exists?(ryan.id)  #=> true
+   ryan.exists?  #=> true
+
+   # Updating is done with 'save' as well
+   # PUT http://api.people.com:3000/people/1.xml
+   #
+   ryan = Person.find(1)
+   ryan.first = 'Rizzle'
+   ryan.save  #=> true
+
+   # And destruction
+   # DELETE http://api.people.com:3000/people/1.xml
+   #
+   ryan = Person.find(1)
+   ryan.destroy  #=> true  # Or Person.delete(ryan.id)
+
+
+=== Protocol
+
+ARes is built on a standard XML format for requesting and submitting resources.  It mirrors the
+RESTful routing built into ActionController, though it's useful to discuss what ARes expects
+outside the context of ActionController as it is not dependent on a Rails-based RESTful implementation.
+
+==== Find
+
+GET Http requests expect the XML form of whatever resource/resources is/are being requested.  So,
+for a request for a single element - the XML of that item is expected in response:
+
+   # Expects a response of
+   #
+   # <person><id>1</id><attribute1>value1</attribute1><attribute2>..</attribute2></person>
+   #
+   # for GET http://api.people.com:3000/people/1.xml
+   #
+   ryan = Person.find(1)
+
+The XML document that is received is used to build a new object of type Person, with each
+XML element becoming an attribute on the object.
+
+   ryan.is_a? Person  #=> true
+   ryan.attribute1  #=> 'value1'
+
+Any complex element (one that contains other elements) becomes its own object:
+
+   # With this response:
+   #
+   # <person><id>1</id><attribute1>value1</attribute1><complex><attribute2>value2</attribute2></complex></person>
+   #
+   # for GET http://api.people.com:3000/people/1.xml
+   #
+   ryan = Person.find(1)
+   ryan.complex  #=> <Person::Complex::xxxxx>
+   ryan.complex.attribute2  #=> 'value2'
+
+Collections can also be requested in a similar fashion
+
+   # Expects a response of
+   #
+   # <people>
+   #  <person><id>1</id><first>Ryan</first></person>
+   #  <person><id>2</id><first>Jim</first></person>
+   # </people>
+   #
+   # for GET http://api.people.com:3000/people.xml
+   #
+   people = Person.find(:all)
+   people.first  #=> <Person::xxx 'first' => 'Ryan' ...>
+   people.last  #=> <Person::xxx 'first' => 'Jim' ...>
+
+==== Create
+
+Creating a new resource submits the xml 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.
+
+  # <person><first>Ryan</first></person>
+  #
+  # is submitted as the body on
+  #
+  # POST http://api.people.com:3000/people.xml
+  # 
+  # when save is called on a new Person object.  An empty response is
+  # is expected with a 'Location' header value:
+  #
+  # Response (200): Location: http://api.people.com:3000/people/2
+  #
+  ryan = Person.new(:first => 'Ryan')
+  ryan.new?  #=> true
+  ryan.save  #=> true
+  ryan.new?  #=> false
+  ryan.id    #=> 2
+
+==== Update
+
+'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.
+
+  # <person><first>Ryan</first></person>
+  #
+  # is submitted as the body on
+  #
+  # PUT http://api.people.com:3000/people/1.xml
+  #
+  # when save is called on an existing Person object.  An empty response is
+  # is expected with code (204)
+  #
+  ryan = Person.find(1)
+  ryan.first #=> 'Ryan'
+  ryan.first = 'Rizzle'
+  ryan.save  #=> true
+
+==== Delete
+
+Destruction of a resource can be invoked as a class and instance method of the resource.
+
+  # A request is made to
+  #
+  # DELETE http://api.people.com:3000/people/1.xml
+  #
+  # for both of these forms.  An empty response with
+  # is expected with response code (200)
+  #
+  ryan = Person.find(1)
+  ryan.destroy  #=> true
+  ryan.exists?  #=> false
+  Person.delete(2)  #=> true
+  Person.exists?(2) #=> false
+
+
+=== Errors & Validation
+
+Error handling and validation is handled in much the same manner as you're used to seeing in
+ActiveRecord.  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/1.xml
+  # #=> Response (404)
+  #
+  ryan = Person.find(1) #=> Raises ActiveResource::ResourceNotFound
+
+==== Validation errors
+
+Creating and updating resources can lead to validation errors - i.e. 'First name cannot be empty' etc...
+These types of errors are denoted in the response by a response code of 400 and the 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.
+
+  # When 
+  #
+  # PUT http://api.people.com:3000/people/1.xml
+  #
+  # is requested with invalid values, the expected response is:
+  #
+  # Response (400):
+  # <errors><error>First cannot be empty</error></errors>
+  #
+  ryan = Person.find(1)
+  ryan.first #=> ''
+  ryan.save  #=> false
+  ryan.errors.invalid?(:first)  #=> true
+  ryan.errors.full_messages  #=> ['First cannot be empty']
+
+
+==== Response errors
+
+If the underlying Http request for an ARes operation results in an error response code, an
+exception will be raised.  The following Http response codes will result in these exceptions:
+
+   200 - 399: Valid response, no exception
+   400: ActiveResource::ResourceInvalid (automatically caught by ARes validation)
+   404: ActiveResource::ResourceNotFound
+   409: ActiveResource::ResourceConflict
+   401 - 499: ActiveResource::ClientError
+   500 - 599: ActiveResource::ServerError
+
+   
+=== Authentication
+
+Many REST apis will require username/password authentication, usually in the form of
+Http authentication.  This can easily be specified by putting the username and password
+in the Url of the ARes site:
+
+   class Person < ActiveResource::Base
+     self.site = "http://ryan:password@api.people.com:3000/"
+   end
+
+For obvious reasons it is best if such services are available over https.
\ No newline at end of file
diff --git a/activeresource/lib/active_resource/base.rb b/activeresource/lib/active_resource/base.rb
index 8babc18507..f530923224 100644
--- a/activeresource/lib/active_resource/base.rb
+++ b/activeresource/lib/active_resource/base.rb
@@ -8,6 +8,7 @@ module ActiveResource
     cattr_accessor :logger
 
     class << self
+      # Gets the URI of the resource's site
       def site
         if defined?(@site)
           @site
@@ -16,20 +17,24 @@ module ActiveResource
         end
       end
 
+      # Set the URI for the REST resources
       def site=(site)
         @connection = nil
         @site = create_site_uri_from(site)
       end
 
+      # Base connection to remote service
       def connection(refresh = false)
         @connection = Connection.new(site) if refresh || @connection.nil?
         @connection
       end
 
-      attr_accessor_with_default(:element_name)    { to_s.underscore }
-      attr_accessor_with_default(:collection_name) { element_name.pluralize }
-      attr_accessor_with_default(:primary_key, 'id')
-
+      attr_accessor_with_default(:element_name)    { to_s.underscore } #:nodoc:
+      attr_accessor_with_default(:collection_name) { element_name.pluralize } #:nodoc:
+      attr_accessor_with_default(:primary_key, 'id') #:nodoc:
+      
+      # Gets the resource prefix
+      #  prefix/collectionname/1.xml
       def prefix(options={})
         default = site.path
         default << '/' unless default[-1..-1] == '/'
@@ -37,6 +42,8 @@ module ActiveResource
         prefix(options)
       end
 
+      # Sets the resource prefix
+      #  prefix/collectionname/1.xml
       def prefix=(value = '/')
         prefix_call = value.gsub(/:\w+/) { |key| "\#{options[#{key}]}" }
         instance_eval <<-end_eval, __FILE__, __LINE__
@@ -48,23 +55,24 @@ module ActiveResource
         raise
       end
 
-      alias_method :set_prefix, :prefix=
+      alias_method :set_prefix, :prefix=  #:nodoc:
 
-      alias_method :set_element_name, :element_name=
-      alias_method :set_collection_name, :collection_name=
+      alias_method :set_element_name, :element_name=  #:nodoc:
+      alias_method :set_collection_name, :collection_name=  #:nodoc:
 
       def element_path(id, options = {})
         "#{prefix(options)}#{collection_name}/#{id}.xml#{query_string(options)}"
       end
 
-      def collection_path(options = {})
+      def collection_path(options = {}) 
         "#{prefix(options)}#{collection_name}.xml#{query_string(options)}"
       end
 
-      alias_method :set_primary_key, :primary_key=
+      alias_method :set_primary_key, :primary_key=  #:nodoc:
 
-      # Person.find(1) # => GET /people/1.xml
-      # StreetAddress.find(1, :person_id => 1) # => GET /people/1/street_addresses/1.xml
+      # Core method for finding resources.  Used similarly to ActiveRecord's find method.
+      #  Person.find(1) # => GET /people/1.xml
+      #  StreetAddress.find(1, :person_id => 1) # => GET /people/1/street_addresses/1.xml
       def find(*arguments)
         scope   = arguments.slice!(0)
         options = arguments.slice!(0) || {}
@@ -80,7 +88,7 @@ module ActiveResource
         connection.delete(element_path(id))
       end
 
-      # True if the resource is found.
+      # Evalutes to <tt>true</tt> if the resource is found.
       def exists?(id, options = {})
         id && !find_single(id, options).nil?
       rescue ActiveResource::ResourceNotFound
@@ -88,16 +96,19 @@ module ActiveResource
       end
 
       private
+        # Find every resource.
         def find_every(options)
           collection = connection.get(collection_path(options)) || []
           collection.collect! { |element| new(element, options) }
         end
 
-        # { :person => person1 }
+        # Find a single resource.
+        #  { :person => person1 }
         def find_single(scope, options)
           new(connection.get(element_path(scope, options)), options)
         end
 
+        # Accepts a URI and creates the site URI from that.
         def create_site_uri_from(site)
           site.is_a?(URI) ? site.dup : URI.parse(site)
         end
@@ -106,6 +117,7 @@ module ActiveResource
           @prefix_parameters ||= prefix_source.scan(/:\w+/).map { |key| key[1..-1].to_sym }.to_set
         end
 
+        # Builds the query string for the request.
         def query_string(options)
           # Omit parameters which appear in the URI path.
           query_params = options.reject { |key, value| prefix_parameters.include?(key) }
@@ -129,8 +141,8 @@ module ActiveResource
         end
     end
 
-    attr_accessor :attributes
-    attr_accessor :prefix_options
+    attr_accessor :attributes #:nodoc:
+    attr_accessor :prefix_options #:nodoc:
 
     def initialize(attributes = {}, prefix_options = {})
       @attributes = {}
@@ -138,19 +150,22 @@ module ActiveResource
       @prefix_options = prefix_options
     end
 
+    # Is the resource a new object?
     def new?
       id.nil?
     end
 
+    # Get the id of the object.
     def id
       attributes[self.class.primary_key]
     end
 
+    # Set the id of the object.
     def id=(id)
       attributes[self.class.primary_key] = id
     end
 
-    # True 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.
+    # True 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+.
     def ==(other)
       other.equal?(self) || (other.instance_of?(self.class) && !other.new? && other.id == id)
     end
@@ -166,19 +181,22 @@ module ActiveResource
       id.hash
     end
 
+    # Delegates to +create+ if a new object, +update+ if its old.
     def save
       new? ? create : update
     end
 
+    # Delete the resource.
     def destroy
       connection.delete(element_path)
     end
 
-    # True if this resource is found.
+    # Evaluates to <tt>true</tt> if this resource is found.
     def exists?
       !new? && self.class.exists?(id, prefix_options)
     end
 
+    # Convert the resource to an XML string
     def to_xml(options={})
       attributes.to_xml({:root => self.class.element_name}.merge(options))
     end
@@ -215,17 +233,19 @@ module ActiveResource
         self.class.connection(refresh)
       end
 
+      # Update the resource on the remote service.
       def update
         connection.put(element_path, to_xml)
       end
 
+      # Create (i.e., save to the remote service) the new resource.
       def create
         returning connection.post(collection_path, to_xml) do |response|
           self.id = id_from_response(response)
         end
       end
 
-      # takes a response from a typical create post and pulls the ID out
+      # Takes a response from a typical create post and pulls the ID out
       def id_from_response(response)
         response['Location'][/\/([^\/]*?)(\.\w+)?$/, 1]
       end
@@ -239,10 +259,12 @@ module ActiveResource
       end
 
     private
+      # Tries to find a resource for a given collection name; if it fails, then the resource is created
       def find_or_create_resource_for_collection(name)
         find_or_create_resource_for(name.to_s.singularize)
       end
-
+      
+      # Tries to find a resource for a given name; if it fails, then the resource is created
       def find_or_create_resource_for(name)
         resource_name = name.to_s.camelize
         resource_name.constantize
@@ -253,7 +275,7 @@ module ActiveResource
         resource
       end
 
-      def method_missing(method_symbol, *arguments)
+      def method_missing(method_symbol, *arguments) #:nodoc:
         method_name = method_symbol.to_s
 
         case method_name.last
diff --git a/activeresource/lib/active_resource/connection.rb b/activeresource/lib/active_resource/connection.rb
index c52d4d4839..528a7cc678 100644
--- a/activeresource/lib/active_resource/connection.rb
+++ b/activeresource/lib/active_resource/connection.rb
@@ -24,7 +24,7 @@ module ActiveResource
 
   class ServerError < ConnectionError;  end  # 5xx Server Error
 
-
+  # Class to handle connections to remote services.
   class Connection
     attr_reader :site
 
@@ -44,27 +44,37 @@ module ActiveResource
       self.site = site
     end
 
+    # Set URI for remote service.
     def site=(site)
       @site = site.is_a?(URI) ? site : URI.parse(site)
     end
 
+    # Execute a GET request.
+    # Used to get (find) resources.
     def get(path)
       from_xml_data(Hash.from_xml(request(:get, path, build_request_headers).body).values.first)
     end
 
+    # Execute a DELETE request (see HTTP protocol documentation if unfamiliar).
+    # Used to delete resources.
     def delete(path)
       request(:delete, path, build_request_headers)
     end
 
+    # Execute a PUT request (see HTTP protocol documentation if unfamiliar).
+    # Used to update resources.
     def put(path, body = '')
       request(:put, path, body, build_request_headers)
     end
 
+    # Execute a POST request.
+    # Used to create new resources.
     def post(path, body = '')
       request(:post, path, body, build_request_headers)
     end
 
     private
+      # Makes request to remote service.
       def request(method, path, *arguments)
         logger.info "#{method.to_s.upcase} #{site.scheme}://#{site.host}:#{site.port}#{path}" if logger
         result = nil
@@ -73,6 +83,7 @@ module ActiveResource
         handle_response(result)
       end
 
+      # Handles response and error codes from remote service.
       def handle_response(response)
         case response.code.to_i
           when 200...400
@@ -92,6 +103,8 @@ module ActiveResource
         end
       end
 
+      # Creates new (or uses currently instantiated) Net::HTTP instance for communication with
+      # remote service and resources.
       def http
         unless @http
           @http             = Net::HTTP.new(@site.host, @site.port)
@@ -102,15 +115,17 @@ module ActiveResource
         @http
       end
       
+      # Builds headers for request to remote service.
       def build_request_headers
         authorization_header.update(self.class.default_header)
       end
       
+      # Sets authorization header; authentication information is pulled from credentials provided with site URI.
       def authorization_header
         (@site.user || @site.password ? { 'Authorization' => 'Basic ' + ["#{@site.user}:#{ @site.password}"].pack('m').delete("\r\n") } : {})
       end
 
-      def logger
+      def logger #:nodoc:
         ActiveResource::Base.logger
       end
 
diff --git a/activeresource/lib/active_resource/http_mock.rb b/activeresource/lib/active_resource/http_mock.rb
index f37bc7d2ad..3ce31a50ea 100644
--- a/activeresource/lib/active_resource/http_mock.rb
+++ b/activeresource/lib/active_resource/http_mock.rb
@@ -1,7 +1,7 @@
 require 'active_resource/connection'
 
 module ActiveResource
-  class InvalidRequestError < StandardError; end
+  class InvalidRequestError < StandardError; end #:nodoc:
 
   class HttpMock
     class Responder
diff --git a/activeresource/lib/active_resource/struct.rb b/activeresource/lib/active_resource/struct.rb
index 6f4ffecc20..ee1f15d781 100644
--- a/activeresource/lib/active_resource/struct.rb
+++ b/activeresource/lib/active_resource/struct.rb
@@ -1,4 +1,13 @@
 module ActiveResource
+  # Class that allows a connection to a remote resource.
+  #  Person = ActiveResource::Struct.new do |p|
+  #    p.uri "http://www.mypeople.com/people"
+  #    p.credentials :username => "mycreds", :password => "wordofpassage"
+  #  end
+  #
+  #  person = Person.find(1)
+  #  person.name = "David"
+  #  person.save!
   class Struct
     def self.create
       Class.new(Base)
diff --git a/activeresource/lib/active_resource/validations.rb b/activeresource/lib/active_resource/validations.rb
index c45655d1ea..76aa7d2f00 100644
--- a/activeresource/lib/active_resource/validations.rb
+++ b/activeresource/lib/active_resource/validations.rb
@@ -1,7 +1,9 @@
 module ActiveResource
-  class ResourceInvalid < ClientError
+  class ResourceInvalid < ClientError  #:nodoc:
   end
 
+  # Active Resource validation is reported to and from this object, which is used by Base#save
+  # to determine whether the object in a valid state to be saved. See usage example in Validations.  
   class Errors
     include Enumerable
     attr_reader :errors
@@ -100,6 +102,38 @@ module ActiveResource
     end
   end
   
+  # Module to allow validation of ActiveResource objects, which are implemented by overriding +Base#validate+ or its variants. 
+  # Each of these methods can inspect the state of the object, which usually means ensuring that a number of 
+  # attributes have a certain value (such as not empty, within a given range, matching a certain regular expression). For example:
+  #
+  #   class Person < ActiveResource::Base
+  #      self.site = "http://www.localhost.com:3000/"
+  #      protected
+  #        def validate
+  #          errors.add_on_empty %w( first_name last_name )
+  #          errors.add("phone_number", "has invalid format") unless phone_number =~ /[0-9]*/
+  #        end
+  #
+  #        def validate_on_create # is only run the first time a new object is saved
+  #          unless valid_member?(self)
+  #            errors.add("membership_discount", "has expired")
+  #          end
+  #        end
+  #
+  #        def validate_on_update
+  #          errors.add_to_base("No changes have occurred") if unchanged_attributes?
+  #        end
+  #   end
+  #   
+  #   person = Person.new("first_name" => "Jim", "phone_number" => "I will not tell you.")
+  #   person.save                         # => false (and doesn't do the save)
+  #   person.errors.empty?                # => false
+  #   person.errors.count                 # => 2
+  #   person.errors.on "last_name"        # => "can't be empty"
+  #   person.attributes = { "last_name" => "Halpert", "phone_number" => "555-5555" }
+  #   person.save                         # => true (and person is now saved to the remote service)
+  #
+  # An Errors object is automatically created for every resource.
   module Validations
     def self.included(base) # :nodoc:
       base.class_eval do