Add primary_key option to belongs_to association

[#765 state:committed]

Signed-off-by: Jeremy Kemper <jeremy@bitsweat.net>

activerecord/CHANGELOG

@@ -1,5 +1,9 @@
 *2.3.3 (July 12, 2009)*
 
+* Added :primary_key option to belongs_to associations.  #765 [Szymon Nowak, Philip Hallstrom, Noel Rocha]
+    # employees.company_name references companies.name
+    Employee.belongs_to :company, :primary_key => 'name', :foreign_key => 'company_name'
+
 * Added :touch option to belongs_to associations that will touch the parent record when the current record is saved or destroyed [DHH]
 
 * Added ActiveRecord::Base#touch to update the updated_at/on attributes (or another specified timestamp) with the current time [DHH]

activerecord/lib/active_record/associations.rb

@@ -957,6 +957,8 @@ def has_one(association_id, options = {})
       #   of the association with an "_id" suffix. So a class that defines a <tt>belongs_to :person</tt> association will use
       #   "person_id" as the default <tt>:foreign_key</tt>. Similarly, <tt>belongs_to :favorite_person, :class_name => "Person"</tt>
       #   will use a foreign key of "favorite_person_id".
+      # [:primary_key]
+      #   Specify the method that returns the primary key of associated object used for the association. By default this is id.
       # [:dependent]
       #   If set to <tt>:destroy</tt>, the associated object is destroyed when this object is. If set to
       #   <tt>:delete</tt>, the associated object is deleted *without* calling its destroy method. This option should not be specified when
@@ -987,6 +989,7 @@ def has_one(association_id, options = {})
       #
       # Option examples:
       #   belongs_to :firm, :foreign_key => "client_of"
+      #   belongs_to :person, :primary_key => "name", :foreign_key => "person_name"
       #   belongs_to :author, :class_name => "Person", :foreign_key => "author_id"
       #   belongs_to :valid_coupon, :class_name => "Coupon", :foreign_key => "coupon_id",
       #              :conditions => 'discounts > #{payments_count}'
@@ -1320,14 +1323,14 @@ def add_counter_cache_callbacks(reflection)
           method_name = "belongs_to_counter_cache_after_create_for_#{reflection.name}".to_sym
           define_method(method_name) do
             association = send(reflection.name)
-            association.class.increment_counter(cache_column, send(reflection.primary_key_name)) unless association.nil?
+            association.class.increment_counter(cache_column, association.id) unless association.nil?
           end
           after_create(method_name)
 
           method_name = "belongs_to_counter_cache_before_destroy_for_#{reflection.name}".to_sym
           define_method(method_name) do
             association = send(reflection.name)
-            association.class.decrement_counter(cache_column, send(reflection.primary_key_name)) unless association.nil?
+            association.class.decrement_counter(cache_column, association.id) unless association.nil?
           end
           before_destroy(method_name)
 
@@ -1519,7 +1522,7 @@ def create_has_one_through_reflection(association_id, options)
 
         mattr_accessor :valid_keys_for_belongs_to_association
         @@valid_keys_for_belongs_to_association = [
-          :class_name, :foreign_key, :foreign_type, :remote, :select, :conditions,
+          :class_name, :primary_key, :foreign_key, :foreign_type, :remote, :select, :conditions,
           :include, :dependent, :counter_cache, :extend, :polymorphic, :readonly,
           :validate, :touch
         ]

activerecord/lib/active_record/associations/belongs_to_association.rb

@@ -14,7 +14,7 @@ def replace(record)
 
         if record.nil?
           if counter_cache_name && !@owner.new_record?
-            @reflection.klass.decrement_counter(counter_cache_name, @owner[@reflection.primary_key_name]) if @owner[@reflection.primary_key_name]
+            @reflection.klass.decrement_counter(counter_cache_name, previous_record_id) if @owner[@reflection.primary_key_name]
           end
 
           @target = @owner[@reflection.primary_key_name] = nil
@@ -27,7 +27,7 @@ def replace(record)
           end
 
           @target = (AssociationProxy === record ? record.target : record)
-          @owner[@reflection.primary_key_name] = record.id unless record.new_record?
+          @owner[@reflection.primary_key_name] = record_id(record) unless record.new_record?
           @updated = true
         end
 
@@ -41,18 +41,36 @@ def updated?
 
       private
         def find_target
-          @reflection.klass.find(
+          find_method = if @reflection.options[:primary_key]
+                          "find_by_#{@reflection.options[:primary_key]}"
+                        else
+                          "find"
+                        end
+          @reflection.klass.send(find_method,
             @owner[@reflection.primary_key_name],
             :select     => @reflection.options[:select],
             :conditions => conditions,
             :include    => @reflection.options[:include],
             :readonly   => @reflection.options[:readonly]
-          )
+          ) if @owner[@reflection.primary_key_name]
         end
 
         def foreign_key_present
           !@owner[@reflection.primary_key_name].nil?
         end
+
+        def record_id(record)
+          record.send(@reflection.options[:primary_key] || :id)
+        end
+
+        def previous_record_id
+          @previous_record_id ||= if @reflection.options[:primary_key]
+                                    previous_record = @owner.send(@reflection.name)
+                                    previous_record.nil? ? nil : previous_record.id
+                                  else
+                                    @owner[@reflection.primary_key_name]
+                                  end
+        end
     end
   end
 end

activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb

@@ -7,7 +7,7 @@ def replace(record)
         else
           @target = (AssociationProxy === record ? record.target : record)
 
-          @owner[@reflection.primary_key_name] = record.id
+          @owner[@reflection.primary_key_name] = record_id(record)
           @owner[@reflection.options[:foreign_type]] = record.class.base_class.name.to_s
 
           @updated = true
@@ -41,6 +41,10 @@ def foreign_key_present
           !@owner[@reflection.primary_key_name].nil?
         end
 
+        def record_id(record)
+          record.send(@reflection.options[:primary_key] || :id)
+        end
+
         def association_class
           @owner[@reflection.options[:foreign_type]] ? @owner[@reflection.options[:foreign_type]].constantize : nil
         end

activerecord/lib/active_record/autosave_association.rb

@@ -340,7 +340,8 @@ def save_belongs_to_association(reflection)
           association.save(!autosave) if association.new_record? || autosave
 
           if association.updated?
-            self[reflection.primary_key_name] = association.id
+            association_id = association.send(reflection.options[:primary_key] || :id)
+            self[reflection.primary_key_name] = association_id
             # TODO: Removing this code doesn't seem to matter…
             if reflection.options[:polymorphic]
               self[reflection.options[:foreign_type]] = association.class.base_class.name.to_s

activerecord/test/cases/associations/belongs_to_associations_test.rb

@@ -14,6 +14,7 @@
 require 'models/comment'
 require 'models/sponsor'
 require 'models/member'
+require 'models/essay'
 
 class BelongsToAssociationsTest < ActiveRecord::TestCase
   fixtures :accounts, :companies, :developers, :projects, :topics,
@@ -25,6 +26,11 @@ def test_belongs_to
     assert !Client.find(3).firm.nil?, "Microsoft should have a firm"
   end
 
+  def test_belongs_to_with_primary_key
+    client = Client.create(:name => "Primary key client", :firm_name => companies(:first_firm).name)
+    assert_equal companies(:first_firm).name, client.firm_with_primary_key.name
+  end
+
   def test_proxy_assignment
     account = Account.find(1)
     assert_nothing_raised { account.firm = account.firm }
@@ -47,6 +53,13 @@ def test_natural_assignment
     assert_equal apple.id, citibank.firm_id
   end
 
+  def test_natural_assignment_with_primary_key
+    apple = Firm.create("name" => "Apple")
+    citibank = Client.create("name" => "Primary key client")
+    citibank.firm_with_primary_key = apple
+    assert_equal apple.name, citibank.firm_name
+  end
+
   def test_no_unexpected_aliasing
     first_firm = companies(:first_firm)
     another_firm = companies(:another_firm)
@@ -69,13 +82,29 @@ def test_creating_the_belonging_object
     assert_equal apple, citibank.firm
   end
 
+  def test_creating_the_belonging_object_with_primary_key
+    client = Client.create(:name => "Primary key client")
+    apple  = client.create_firm_with_primary_key("name" => "Apple")
+    assert_equal apple, client.firm_with_primary_key
+    client.save
+    client.reload
+    assert_equal apple, client.firm_with_primary_key
+  end
+
   def test_building_the_belonging_object
     citibank = Account.create("credit_limit" => 10)
     apple    = citibank.build_firm("name" => "Apple")
     citibank.save
     assert_equal apple.id, citibank.firm_id
   end
 
+  def test_building_the_belonging_object_with_primary_key
+    client = Client.create(:name => "Primary key client")
+    apple  = client.build_firm_with_primary_key("name" => "Apple")
+    client.save
+    assert_equal apple.name, client.firm_name
+  end
+
   def test_natural_assignment_to_nil
     client = Client.find(3)
     client.firm = nil
@@ -84,6 +113,14 @@ def test_natural_assignment_to_nil
     assert_nil client.client_of
   end
 
+  def test_natural_assignment_to_nil_with_primary_key
+    client = Client.create(:name => "Primary key client", :firm_name => companies(:first_firm).name)
+    client.firm_with_primary_key = nil
+    client.save
+    assert_nil client.firm_with_primary_key(true)
+    assert_nil client.client_of
+  end
+
   def test_with_different_class_name
     assert_equal Company.find(1).name, Company.find(3).firm_with_other_name.name
     assert_not_nil Company.find(3).firm_with_other_name, "Microsoft should have a firm"
@@ -110,6 +147,17 @@ def test_belongs_to_counter
     assert_equal 0, Topic.find(debate.id).send(:read_attribute, "replies_count"), "First reply deleted"
   end
 
+  def test_belongs_to_with_primary_key_counter
+    debate = Topic.create("title" => "debate")
+    assert_equal 0, debate.send(:read_attribute, "replies_count"), "No replies yet"
+
+    trash = debate.replies_with_primary_key.create("title" => "blah!", "content" => "world around!")
+    assert_equal 1, Topic.find(debate.id).send(:read_attribute, "replies_count"), "First reply created"
+
+    trash.destroy
+    assert_equal 0, Topic.find(debate.id).send(:read_attribute, "replies_count"), "First reply deleted"
+  end
+
   def test_belongs_to_counter_with_assigning_nil
     p = Post.find(1)
     c = Comment.find(1)
@@ -122,6 +170,18 @@ def test_belongs_to_counter_with_assigning_nil
     assert_equal 1, Post.find(p.id).comments.size
   end
 
+  def test_belongs_to_with_primary_key_counter_with_assigning_nil
+    debate = Topic.create("title" => "debate")
+    reply  = Reply.create("title" => "blah!", "content" => "world around!", "parent_title" => "debate")
+
+    assert_equal debate.title, reply.parent_title
+    assert_equal 1, Topic.find(debate.id).send(:read_attribute, "replies_count")
+
+    reply.topic_with_primary_key = nil
+
+    assert_equal 0, Topic.find(debate.id).send(:read_attribute, "replies_count")
+  end
+
   def test_belongs_to_counter_with_reassigning
     t1 = Topic.create("title" => "t1")
     t2 = Topic.create("title" => "t2")
@@ -219,6 +279,18 @@ def test_assignment_before_child_saved
     assert_equal firm, final_cut.firm(true)
   end
 
+  def test_assignment_before_child_saved_with_primary_key
+    final_cut = Client.new("name" => "Final Cut")
+    firm = Firm.find(1)
+    final_cut.firm_with_primary_key = firm
+    assert final_cut.new_record?
+    assert final_cut.save
+    assert !final_cut.new_record?
+    assert !firm.new_record?
+    assert_equal firm, final_cut.firm_with_primary_key
+    assert_equal firm, final_cut.firm_with_primary_key(true)
+  end
+
   def test_new_record_with_foreign_key_but_no_object
     c = Client.new("firm_id" => 1)
     assert_equal Firm.find(:first), c.firm_with_basic_id
@@ -297,26 +369,52 @@ def test_polymorphic_assignment_foreign_type_field_updating
     member = Member.create
     sponsor.sponsorable = member
     assert_equal "Member", sponsor.sponsorable_type
-    
+
     # should update when assigning a new record
     sponsor = Sponsor.new
     member = Member.new
     sponsor.sponsorable = member
     assert_equal "Member", sponsor.sponsorable_type
   end
-
+
+  def test_polymorphic_assignment_with_primary_key_foreign_type_field_updating
+    # should update when assigning a saved record
+    essay = Essay.new
+    writer = Author.create(:name => "David")
+    essay.writer = writer
+    assert_equal "Author", essay.writer_type
+
+    # should update when assigning a new record
+    essay = Essay.new
+    writer = Author.new
+    essay.writer = writer
+    assert_equal "Author", essay.writer_type
+  end
+
   def test_polymorphic_assignment_updates_foreign_id_field_for_new_and_saved_records
     sponsor = Sponsor.new
     saved_member = Member.create
     new_member = Member.new
-    
+
     sponsor.sponsorable = saved_member
     assert_equal saved_member.id, sponsor.sponsorable_id
-    
+
     sponsor.sponsorable = new_member
     assert_equal nil, sponsor.sponsorable_id
   end
 
+  def test_polymorphic_assignment_with_primary_key_updates_foreign_id_field_for_new_and_saved_records
+    essay = Essay.new
+    saved_writer = Author.create(:name => "David")
+    new_writer = Author.new
+
+    essay.writer = saved_writer
+    assert_equal saved_writer.name, essay.writer_id
+
+    essay.writer = new_writer
+    assert_equal nil, essay.writer_id
+  end
+
   def test_belongs_to_proxy_should_not_respond_to_private_methods
     assert_raise(NoMethodError) { companies(:first_firm).private_method }
     assert_raise(NoMethodError) { companies(:second_client).firm.private_method }

activerecord/test/cases/base_test.rb

@@ -2014,7 +2014,7 @@ def test_inspect_class
 
   def test_inspect_instance
     topic = topics(:first)
-    assert_equal %(#<Topic id: 1, title: "The First Topic", author_name: "David", author_email_address: "david@loudthinking.com", written_on: "#{topic.written_on.to_s(:db)}", bonus_time: "#{topic.bonus_time.to_s(:db)}", last_read: "#{topic.last_read.to_s(:db)}", content: "Have a nice day", approved: false, replies_count: 1, parent_id: nil, type: nil>), topic.inspect
+    assert_equal %(#<Topic id: 1, title: "The First Topic", author_name: "David", author_email_address: "david@loudthinking.com", written_on: "#{topic.written_on.to_s(:db)}", bonus_time: "#{topic.bonus_time.to_s(:db)}", last_read: "#{topic.last_read.to_s(:db)}", content: "Have a nice day", approved: false, replies_count: 1, parent_id: nil, parent_title: nil, type: nil>), topic.inspect
   end
 
   def test_inspect_new_instance

activerecord/test/cases/reflection_test.rb

@@ -21,25 +21,25 @@ def test_column_null_not_null
 
   def test_read_attribute_names
     assert_equal(
-      %w( id title author_name author_email_address bonus_time written_on last_read content approved replies_count parent_id type ).sort,
+      %w( id title author_name author_email_address bonus_time written_on last_read content approved replies_count parent_id parent_title type ).sort,
       @first.attribute_names
     )
   end
 
   def test_columns
-    assert_equal 12, Topic.columns.length
+    assert_equal 13, Topic.columns.length
   end
 
   def test_columns_are_returned_in_the_order_they_were_declared
     column_names = Topic.columns.map { |column| column.name }
-    assert_equal %w(id title author_name author_email_address written_on bonus_time last_read content approved replies_count parent_id type), column_names
+    assert_equal %w(id title author_name author_email_address written_on bonus_time last_read content approved replies_count parent_id parent_title type), column_names
   end
 
   def test_content_columns
     content_columns        = Topic.content_columns
     content_column_names   = content_columns.map {|column| column.name}
-    assert_equal 8, content_columns.length
-    assert_equal %w(title author_name author_email_address written_on bonus_time last_read content approved).sort, content_column_names.sort
+    assert_equal 9, content_columns.length
+    assert_equal %w(title author_name author_email_address written_on bonus_time last_read content approved parent_title).sort, content_column_names.sort
   end
 
   def test_column_string_type_and_limit

activerecord/test/models/author.rb

@@ -87,6 +87,8 @@ def testing_proxy_target
   has_many :tags,     :through => :posts # through has_many :through
   has_many :post_categories, :through => :posts, :source => :categories
 
+  has_one :essay, :primary_key => :name, :as => :writer
+
   belongs_to :author_address, :dependent => :destroy
   belongs_to :author_address_extra, :dependent => :delete, :class_name => "AuthorAddress"
 

activerecord/test/models/company.rb

@@ -84,6 +84,7 @@ class Client < Company
   belongs_to :firm_with_select, :class_name => "Firm", :foreign_key => "firm_id", :select => "id"
   belongs_to :firm_with_other_name, :class_name => "Firm", :foreign_key => "client_of"
   belongs_to :firm_with_condition, :class_name => "Firm", :foreign_key => "client_of", :conditions => ["1 = ?", 1]
+  belongs_to :firm_with_primary_key, :class_name => "Firm", :primary_key => "name", :foreign_key => "firm_name"
   belongs_to :readonly_firm, :class_name => "Firm", :foreign_key => "firm_id", :readonly => true
 
   # Record destruction so we can test whether firm.clients.clear has

activerecord/test/models/essay.rb

@@ -0,0 +1,3 @@
+class Essay < ActiveRecord::Base
+  belongs_to :writer, :primary_key => :name, :polymorphic => true
+end