Add ability to specify :default value for relationships

* Like with Property, :default may be a value or an object that
  responds to #call

[#1099 state:resolved]

dm-core.gemspec

@@ -9,7 +9,7 @@ Gem::Specification.new do |s|
 
   s.required_rubygems_version = Gem::Requirement.new(">= 0") if s.respond_to? :required_rubygems_version=
   s.authors = ["Dan Kubb"]
-  s.date = %q{2010-03-18}
+  s.date = %q{2010-03-27}
   s.description = %q{Faster, Better, Simpler.}
   s.email = %q{dan.kubb@gmail.com}
   s.extra_rdoc_files = [
@@ -82,6 +82,7 @@ Gem::Specification.new do |s|
      "lib/dm-core/support/lazy_array.rb",
      "lib/dm-core/support/logger.rb",
      "lib/dm-core/support/naming_conventions.rb",
+     "lib/dm-core/support/subject.rb",
      "lib/dm-core/transaction.rb",
      "lib/dm-core/type.rb",
      "lib/dm-core/types/boolean.rb",
@@ -137,7 +138,10 @@ Gem::Specification.new do |s|
      "spec/semipublic/adapters/sqlite3_adapter_spec.rb",
      "spec/semipublic/adapters/sqlserver_adapter_spec.rb",
      "spec/semipublic/adapters/yaml_adapter_spec.rb",
+     "spec/semipublic/associations/many_to_many_spec.rb",
      "spec/semipublic/associations/many_to_one_spec.rb",
+     "spec/semipublic/associations/one_to_many_spec.rb",
+     "spec/semipublic/associations/one_to_one_spec.rb",
      "spec/semipublic/associations/relationship_spec.rb",
      "spec/semipublic/associations_spec.rb",
      "spec/semipublic/collection_spec.rb",
@@ -150,6 +154,7 @@ Gem::Specification.new do |s|
      "spec/semipublic/resource_spec.rb",
      "spec/semipublic/shared/condition_shared_spec.rb",
      "spec/semipublic/shared/resource_shared_spec.rb",
+     "spec/semipublic/shared/subject_shared_spec.rb",
      "spec/spec.opts",
      "spec/spec_helper.rb",
      "spec/unit/array_spec.rb",
@@ -213,7 +218,10 @@ Gem::Specification.new do |s|
      "spec/semipublic/adapters/sqlite3_adapter_spec.rb",
      "spec/semipublic/adapters/sqlserver_adapter_spec.rb",
      "spec/semipublic/adapters/yaml_adapter_spec.rb",
+     "spec/semipublic/associations/many_to_many_spec.rb",
      "spec/semipublic/associations/many_to_one_spec.rb",
+     "spec/semipublic/associations/one_to_many_spec.rb",
+     "spec/semipublic/associations/one_to_one_spec.rb",
      "spec/semipublic/associations/relationship_spec.rb",
      "spec/semipublic/associations_spec.rb",
      "spec/semipublic/collection_spec.rb",
@@ -226,6 +234,7 @@ Gem::Specification.new do |s|
      "spec/semipublic/resource_spec.rb",
      "spec/semipublic/shared/condition_shared_spec.rb",
      "spec/semipublic/shared/resource_shared_spec.rb",
+     "spec/semipublic/shared/subject_shared_spec.rb",
      "spec/spec_helper.rb",
      "spec/unit/array_spec.rb",
      "spec/unit/hash_spec.rb",

lib/dm-core.rb

@@ -66,7 +66,7 @@ module ActiveSupport
 require 'dm-core/support/assertions'
 require 'dm-core/support/lazy_array'
 require 'dm-core/support/hook'
-
+require 'dm-core/support/subject'
 
 require 'dm-core/model'
 require 'dm-core/model/descendant_set'

lib/dm-core/associations/many_to_one.rb

@@ -114,6 +114,9 @@ def resource_for(source, other_query = nil)
         def get(source, other_query = nil)
           lazy_load(source) unless loaded?(source)
 
+          # set the default if it is not already set
+          set(source, default_for(source)) unless loaded?(source)
+
           resource = get!(source)
           if other_query.nil? || query_for(source, other_query).conditions.matches?(resource)
             resource

lib/dm-core/associations/one_to_many.rb

@@ -44,7 +44,7 @@ def collection_for(source, other_query = nil)
           collection.source       = source
 
           # make the collection empty if the source is not saved
-          collection.replace([]) unless source.saved?
+          collection.replace(default_for(source)) unless source.saved?
 
           collection
         end
@@ -70,6 +70,11 @@ def set(source, targets)
           get!(source).replace(targets)
         end
 
+        # @api semipublic
+        def default_for(source)
+          Array(super)
+        end
+
         private
 
         # @api semipublic

lib/dm-core/associations/one_to_one.rb

@@ -6,14 +6,19 @@ class Relationship < Associations::Relationship
           superclass.send("#{visibility}_instance_methods", false).each do |method|
             undef_method method unless method.to_s == 'initialize'
           end
+
+          # remove mixed in methods
+          undef_method *DataMapper::Subject.send("#{visibility}_instance_methods", false)
         end
 
         # Loads (if necessary) and returns association target
         # for given source
         #
         # @api semipublic
         def get(source, other_query = nil)
-          return unless loaded?(source) || valid_source?(source)
+          unless loaded?(source) || valid_source?(source)
+            set(source, default_for(source))
+          end
 
           relationship.get(source, other_query).first
         end
@@ -26,6 +31,11 @@ def set(source, target)
           relationship.set(source, [ target ].compact).first
         end
 
+        # @api semipublic
+        def default_for(source)
+          relationship.default_for(source).first
+        end
+
         # @api public
         def kind_of?(klass)
           super || relationship.kind_of?(klass)

lib/dm-core/associations/relationship.rb

@@ -7,8 +7,9 @@ module Associations
     # with methods like get and set overridden.
     class Relationship
       include DataMapper::Assertions
+      include Subject
 
-      OPTIONS = [ :child_repository_name, :parent_repository_name, :child_key, :parent_key, :min, :max, :inverse, :reader_visibility, :writer_visibility ].to_set
+      OPTIONS = [ :child_repository_name, :parent_repository_name, :child_key, :parent_key, :min, :max, :inverse, :reader_visibility, :writer_visibility, :default ].to_set
 
       # Relationship name
       #
@@ -447,6 +448,7 @@ def initialize(name, child_model, parent_model, options = {})
         @max                    = @options[:max]
         @reader_visibility      = @options.fetch(:reader_visibility, :public)
         @writer_visibility      = @options.fetch(:writer_visibility, :public)
+        @default                = @options.fetch(:default, nil)
 
         # TODO: normalize the @query to become :conditions => AndOperation
         #  - Property/Relationship/Path should be left alone

lib/dm-core/property.rb

@@ -290,6 +290,7 @@ module DataMapper
   #   see SingleTableInheritance for more on how to use <tt>Class</tt> columns.
   class Property
     include DataMapper::Assertions
+    include Subject
     extend Deprecate
     extend Equalizer
 
@@ -514,7 +515,7 @@ def get(resource)
       if loaded?(resource)
         get!(resource)
       else
-        set(resource, default? ? default_for(resource) : nil)
+        set(resource, default_for(resource))
       end
     end
 
@@ -687,38 +688,6 @@ def load(value)
       typecast(value)
     end
 
-    # Returns a default value of the
-    # property for given resource.
-    #
-    # When default value is a callable object,
-    # it is called with resource and property passed
-    # as arguments.
-    #
-    # @param [Resource] resource
-    #   the model instance for which the default is to be set
-    #
-    # @return [Object]
-    #   the default value of this property for +resource+
-    #
-    # @api semipublic
-    def default_for(resource)
-      if @default.respond_to?(:call)
-        @default.call(resource, self)
-      else
-        @default.try_dup
-      end
-    end
-
-    # Returns true if the property has a default value
-    #
-    # @return [Boolean]
-    #   true if the property has a default value
-    #
-    # @api semipublic
-    def default?
-      @options.key?(:default)
-    end
-
     # Returns given value unchanged for core types and
     # uses +dump+ method of the property type for custom types.
     #

lib/dm-core/resource.rb

@@ -894,10 +894,12 @@ def child_collections
     # @api private
     def _create
       # set defaults for new resource
-      properties.each do |property|
-        unless property.serial? || property.loaded?(self)
-          property.set(self, property.default_for(self))
-        end
+      (properties | relationships.values).each do |subject|
+        next if subject.respond_to?(:serial?) && subject.serial? ||
+                subject.loaded?(self)                            ||
+                !subject.default?
+
+        subject.set(self, subject.default_for(self))
       end
 
       @_repository = repository

lib/dm-core/support/subject.rb

@@ -0,0 +1,33 @@
+module DataMapper
+  module Subject
+    # Returns a default value of the subject for given resource
+    #
+    # When default value is a callable object, it is called with resource
+    # and subject passed as arguments.
+    #
+    # @param [Resource] resource
+    #   the model instance for which the default is to be set
+    #
+    # @return [Object]
+    #   the default value of this subject for +resource+
+    #
+    # @api semipublic
+    def default_for(resource)
+      if @default.respond_to?(:call)
+        @default.call(resource, self)
+      else
+        @default.try_dup
+      end
+    end
+
+    # Returns true if the subject has a default value
+    #
+    # @return [Boolean]
+    #   true if the subject has a default value
+    #
+    # @api semipublic
+    def default?
+      @options.key?(:default)
+    end
+  end
+end

spec/semipublic/associations/many_to_many_spec.rb

@@ -0,0 +1,40 @@
+require File.expand_path(File.join(File.dirname(__FILE__), '..', '..', 'spec_helper'))
+
+describe 'One to Many Associations' do
+  before :all do
+    module ::Blog
+      class Article
+        include DataMapper::Resource
+
+        property :title, String, :key => true
+        property :body,  Text,   :required => true
+      end
+    end
+
+    @article_model = Blog::Article
+  end
+
+  supported_by :all do
+    before :all do
+      @article = @article_model.new(:title => 'DataMapper Rocks!', :body => 'TSIA')
+    end
+
+    describe 'acts like a subject' do
+      before do
+        n = @article_model.n
+
+        @subject_without_default       = @article_model.has(n, :without_default,       @article_model, :through => DataMapper::Resource)
+        @subject_with_default          = @article_model.has(n, :with_default,          @article_model, :through => DataMapper::Resource, :default => [ @article ])
+        @subject_with_default_callable = @article_model.has(n, :with_default_callable, @article_model, :through => DataMapper::Resource, :default => lambda { |resource, relationship| [ @article ] })
+
+        @subject_without_default_value       = []
+        @subject_with_default_value          = [ @article ]
+        @subject_with_default_callable_value = [ @article ]
+
+        @resource = @article_model.new
+      end
+
+      it_should_behave_like 'A semipublic Subject'
+    end
+  end
+end

spec/semipublic/associations/many_to_one_spec.rb

@@ -32,5 +32,21 @@ class ::Comment
     end
 
     it_should_behave_like 'A semipublic Resource'
+
+    describe 'acts like a subject' do
+      before do
+        @subject_without_default       = @user_model.belongs_to(:without_default,       @user_model)
+        @subject_with_default          = @user_model.belongs_to(:with_default,          @user_model, :default => @user)
+        @subject_with_default_callable = @user_model.belongs_to(:with_default_callable, @user_model, :default => lambda { |resource, relationship| @user })
+
+        @subject_without_default_value       = nil
+        @subject_with_default_value          = @user
+        @subject_with_default_callable_value = @user
+
+        @resource = @user_model.new
+      end
+
+      it_should_behave_like 'A semipublic Subject'
+    end
   end
 end

spec/semipublic/associations/one_to_many_spec.rb

@@ -0,0 +1,40 @@
+require File.expand_path(File.join(File.dirname(__FILE__), '..', '..', 'spec_helper'))
+
+describe 'One to Many Associations' do
+  before :all do
+    module ::Blog
+      class Article
+        include DataMapper::Resource
+
+        property :title, String, :key => true
+        property :body,  Text,   :required => true
+      end
+    end
+
+    @article_model = Blog::Article
+  end
+
+  supported_by :all do
+    before :all do
+      @article = @article_model.new(:title => 'DataMapper Rocks!', :body => 'TSIA')
+    end
+
+    describe 'acts like a subject' do
+      before do
+        n = @article_model.n
+
+        @subject_without_default       = @article_model.has(n, :without_default,       @article_model)
+        @subject_with_default          = @article_model.has(n, :with_default,          @article_model, :default => [ @article ])
+        @subject_with_default_callable = @article_model.has(n, :with_default_callable, @article_model, :default => lambda { |resource, relationship| [ @article ] })
+
+        @subject_without_default_value       = []
+        @subject_with_default_value          = [ @article ]
+        @subject_with_default_callable_value = [ @article ]
+
+        @resource = @article_model.new
+      end
+
+      it_should_behave_like 'A semipublic Subject'
+    end
+  end
+end

spec/semipublic/associations/one_to_one_spec.rb

@@ -0,0 +1,38 @@
+require File.expand_path(File.join(File.dirname(__FILE__), '..', '..', 'spec_helper'))
+
+describe 'One to One Associations' do
+  before :all do
+    module ::Blog
+      class Article
+        include DataMapper::Resource
+
+        property :title, String, :key => true
+        property :body,  Text,   :required => true
+      end
+    end
+
+    @article_model = Blog::Article
+  end
+
+  supported_by :all do
+    before :all do
+      @article = @article_model.new(:title => 'DataMapper Rocks!', :body => 'TSIA')
+    end
+
+    describe 'acts like a subject' do
+      before do
+        @subject_without_default       = @article_model.has(1, :without_default,       @article_model)
+        @subject_with_default          = @article_model.has(1, :with_default,          @article_model, :default => @article)
+        @subject_with_default_callable = @article_model.has(1, :with_default_callable, @article_model, :default => lambda { |resource, relationship| @article })
+
+        @subject_without_default_value       = nil
+        @subject_with_default_value          = @article
+        @subject_with_default_callable_value = @article
+
+        @resource = @article_model.new
+      end
+
+      it_should_behave_like 'A semipublic Subject'
+    end
+  end
+end