adding initial support for belongs_to associations

history.txt

@@ -11,9 +11,11 @@
   * Fixed issue with active_support in Rails3 and text in README for JSON.
   * Refactoring of properties, added read_attribute and write_attribute methods.
   * Now possible to send anything to update_attribtues method. Invalid or readonly attributes will be ignored.
+  * Attributes with arrays are *always* instantiated as a CastedArray.
 
 * Major enhancements
   * Added support for anonymous CastedModels defined in Documents
+  * Added initial support for simple belongs_to associations 
 
 == 1.0.0.beta5
 

lib/couchrest/extended_document.rb

@@ -19,6 +19,7 @@ module CouchRest
     include CouchRest::Mixins::Collection
     include CouchRest::Mixins::AttributeProtection
     include CouchRest::Mixins::Attributes
+    include CouchRest::Mixins::Associations
 
     # Including validation here does not work due to the way inheritance is handled.
     #include CouchRest::Validation

lib/couchrest/mixins.rb

@@ -10,3 +10,4 @@ require File.join(mixins_dir, 'class_proxy')
 require File.join(mixins_dir, 'collection')
 require File.join(mixins_dir, 'attribute_protection')
 require File.join(mixins_dir, 'attributes')
+require File.join(mixins_dir, 'associations')

lib/couchrest/mixins/associations.rb

@@ -0,0 +1,58 @@
+module CouchRest
+  module Mixins
+    module Associations
+
+      # Basic support for relationships between ExtendedDocuments
+      
+      def self.included(base)
+        base.extend(ClassMethods)
+      end
+
+      module ClassMethods
+
+        def belongs_to(attrib, *options)
+          opts = {
+            :foreign_key => attrib.to_s + '_id',
+            :class_name => attrib.to_s.camelcase
+          }
+          case options.first
+          when Hash
+            opts.merge!(options.first)
+          end
+
+          begin
+            opts[:class] = opts[:class_name].constantize
+          rescue
+            raise "Unable to convert belongs_to class name into Constant for #{self.name}##{attrib}"
+          end
+
+          prop = property(opts[:foreign_key])
+
+          create_belongs_to_getter(attrib, prop, opts)
+          create_belongs_to_setter(attrib, prop, opts)
+
+          prop
+        end
+
+        def create_belongs_to_getter(attrib, property, options)
+          class_eval <<-EOS, __FILE__, __LINE__ + 1
+            def #{attrib}
+              @#{attrib} ||= #{options[:class_name]}.get(self.#{options[:foreign_key]})
+            end
+          EOS
+        end
+
+        def create_belongs_to_setter(attrib, property, options)
+          class_eval <<-EOS, __FILE__, __LINE__ + 1
+            def #{attrib}=(value)
+              @#{attrib} = value
+              self.#{options[:foreign_key]} = value.nil? ? nil : value.id
+            end
+          EOS
+        end
+
+      end
+
+    end
+  end
+end

spec/couchrest/assocations_spec.rb

@@ -0,0 +1,79 @@
+# encoding: utf-8
+require File.expand_path('../../spec_helper', __FILE__)
+
+class Client < CouchRest::ExtendedDocument
+  use_database DB
+
+  property :name
+  property :tax_code
+end
+
+class SaleInvoice < CouchRest::ExtendedDocument  
+  use_database DB
+
+  belongs_to :client
+  belongs_to :alternate_client, :class_name => 'Client', :foreign_key => 'alt_client_id'
+
+  property :date, Date
+  property :price, Integer 
+end
+
+
+describe "Assocations" do
+
+  describe "of type belongs to" do
+
+    before :each do
+      @invoice = SaleInvoice.create(:price => "sam", :price => 2000)
+      @client = Client.create(:name => "Sam Lown")
+    end
+
+    it "should create a foreign key property with setter and getter" do
+      @invoice.properties.find{|p| p.name == 'client_id'}.should_not be_nil
+      @invoice.respond_to?(:client_id).should be_true
+      @invoice.respond_to?("client_id=").should be_true
+    end
+
+    it "should set the property and provide object when set" do
+      @invoice.client = @client
+      @invoice.client_id.should eql(@client.id)
+      @invoice.client.should eql(@client)
+    end
+
+    it "should set the attribute, save and return" do
+      @invoice.client = @client
+      @invoice.save
+      @invoice = SaleInvoice.get(@invoice.id)
+      @invoice.client.id.should eql(@client.id)
+    end
+
+    it "should remove the association if nil is provided" do
+      @invoice.client = @client
+      @invoice.client = nil
+      @invoice.client_id.should be_nil
+    end
+
+    it "should raise error if class name does not exist" do
+      lambda {
+        class TestBadAssoc < CouchRest::ExtendedDocument
+          belongs_to :test_bad_item
+        end
+      }.should raise_error
+    end
+
+    it "should allow override of foreign key" do
+      @invoice.respond_to?(:alternate_client).should be_true
+      @invoice.respond_to?("alternate_client=").should be_true
+      @invoice.properties.find{|p| p.name == 'alt_client_id'}.should_not be_nil
+    end
+
+    it "should allow override of foreign key and save" do
+      @invoice.alternate_client = @client
+      @invoice.save
+      @invoice = SaleInvoice.get(@invoice.id)
+      @invoice.alternate_client.id.should eql(@client.id)
+    end
+
+  end
+
+end