Accept a lambda for context in factory

lib/draper/decorated_association.rb

@@ -9,21 +9,17 @@ def initialize(owner, association, options)
       @association = association
 
       @scope = options[:scope]
-      @context = options.fetch(:context, ->(context){ context })
 
-      @factory = Draper::Factory.new(options.slice(:with))
+      decorator_class = options[:with]
+      context = options.fetch(:context, ->(context){ context })
+      @factory = Draper::Factory.new(with: decorator_class, context: context)
     end
 
     def call
       decorate unless defined?(@decorated)
       @decorated
     end
 
-    def context
-      return @context.call(owner.context) if @context.respond_to?(:call)
-      @context
-    end
-
     private
 
     attr_reader :factory, :owner, :association, :scope
@@ -32,7 +28,7 @@ def decorate
       associated = owner.source.send(association)
       associated = associated.send(scope) if scope
 
-      @decorated = factory.decorate(associated, context: context)
+      @decorated = factory.decorate(associated, context_args: owner.context)
     end
 
   end

lib/draper/decorates_assigned.rb

@@ -19,7 +19,12 @@ module DecoratesAssigned
     #   @param [Symbols*] variables
     #     names of the instance variables to decorate (without the `@`).
     #   @param [Hash] options
-    #     see {Factory#initialize}
+    #   @option options [Decorator, CollectionDecorator] :with (nil)
+    #     decorator class to use. If nil, it is inferred from the instance
+    #     variable.
+    #   @option options [Hash, #call] :context
+    #     extra data to be stored in the decorator. If a Proc is given, it will
+    #     be passed the controller and should return a new context hash.
     def decorates_assigned(*variables)
       factory = Draper::Factory.new(variables.extract_options!)
 
@@ -29,7 +34,7 @@ def decorates_assigned(*variables)
 
         define_method variable do
           return instance_variable_get(decorated) if instance_variable_defined?(decorated)
-          instance_variable_set decorated, factory.decorate(instance_variable_get(undecorated))
+          instance_variable_set decorated, factory.decorate(instance_variable_get(undecorated), context_args: self)
         end
 
         helper_method variable

lib/draper/factory.rb

@@ -2,11 +2,13 @@ module Draper
   class Factory
     # Creates a decorator factory.
     #
-    # @option options [Decorator,CollectionDecorator] :with (nil)
+    # @option options [Decorator, CollectionDecorator] :with (nil)
     #   decorator class to use. If nil, it is inferred from the object
     #   passed to {#decorate}.
-    # @option options [Hash] context
-    #   extra data to be stored in created decorators.
+    # @option options [Hash, #call] context
+    #   extra data to be stored in created decorators. If a proc is given, it
+    #   will be called each time {#decorate} is called and its return value
+    #   will be used as the context.
     def initialize(options = {})
       options.assert_valid_keys(:with, :context)
       @decorator_class = options.delete(:with)
@@ -21,6 +23,8 @@ def initialize(options = {})
     # @option options [Hash] context
     #   extra data to be stored in the decorator. Overrides any context passed
     #   to the constructor.
+    # @option options [Object, Array] context_args (nil)
+    #   argument(s) to be passed to the context proc.
     # @return [Decorator, CollectionDecorator] the decorated object.
     def decorate(source, options = {})
       return nil if source.nil?
@@ -31,13 +35,15 @@ def decorate(source, options = {})
 
     attr_reader :decorator_class, :default_options
 
+    # @private
     class Worker
       def initialize(decorator_class, source)
         @decorator_class = decorator_class
         @source = source
       end
 
       def call(options)
+        update_context options
         decorator.call(source, options)
       end
 
@@ -71,6 +77,11 @@ def decorator_class
       def source_decorator_class
         source.decorator_class if source.respond_to?(:decorator_class)
       end
+
+      def update_context(options)
+        args = options.delete(:context_args)
+        options[:context] = options[:context].call(*args) if options[:context].respond_to?(:call)
+      end
     end
   end
 end

spec/draper/decorated_association_spec.rb

@@ -4,144 +4,78 @@ module Draper
   describe DecoratedAssociation do
 
     describe "#initialize" do
-      describe "options validation" do
-        it "does not raise error on valid options" do
-          valid_options = {with: Decorator, scope: :foo, context: {}}
-          expect{DecoratedAssociation.new(Decorator.new(Model.new), :association, valid_options)}.not_to raise_error
-        end
-
-        it "raises error on invalid options" do
-          expect{DecoratedAssociation.new(Decorator.new(Model.new), :association, foo: "bar")}.to raise_error ArgumentError, /Unknown key/
-        end
+      it "accepts valid options" do
+        valid_options = {with: Decorator, scope: :foo, context: {}}
+        expect{DecoratedAssociation.new(Decorator.new(Model.new), :association, valid_options)}.not_to raise_error
       end
-    end
-
-    describe "#call" do
-      let(:context) { {some: "context"} }
-      let(:options) { {} }
 
-      let(:decorated_association) do
-        owner = double(context: nil, source: double(association: associated))
-
-        DecoratedAssociation.new(owner, :association, options).tap do |decorated_association|
-          decorated_association.stub context: context
-        end
+      it "rejects invalid options" do
+        expect{DecoratedAssociation.new(Decorator.new(Model.new), :association, foo: "bar")}.to raise_error ArgumentError, /Unknown key/
       end
 
-      context "for a singular association" do
-        let(:associated) { Model.new }
-
-        context "when :with option was given" do
-          let(:options) { {with: Decorator} }
-
-          it "uses the specified decorator" do
-            Decorator.should_receive(:decorate).with(associated, context: context).and_return(:decorated)
-            expect(decorated_association.call).to be :decorated
-          end
-        end
+      it "creates a factory" do
+        options = {with: Decorator, context: {foo: "bar"}}
 
-        context "when :with option was not given" do
-          it "infers the decorator" do
-            associated.stub decorator_class: OtherDecorator
-
-            OtherDecorator.should_receive(:decorate).with(associated, context: context).and_return(:decorated)
-            expect(decorated_association.call).to be :decorated
-          end
-        end
+        Factory.should_receive(:new).with(options)
+        DecoratedAssociation.new(double, :association, options)
       end
 
-      context "for a collection association" do
-        let(:associated) { [] }
-
-        context "when :with option is a collection decorator" do
-          let(:options) { {with: ProductsDecorator} }
-
-          it "uses the specified decorator" do
-            ProductsDecorator.should_receive(:decorate).with(associated, context: context).and_return(:decorated_collection)
-            expect(decorated_association.call).to be :decorated_collection
-          end
-        end
-
-        context "when :with option is a singular decorator" do
-          let(:options) { {with: ProductDecorator} }
-
-          it "uses a CollectionDecorator of the specified decorator" do
-            ProductDecorator.should_receive(:decorate_collection).with(associated, context: context).and_return(:decorated_collection)
-            expect(decorated_association.call).to be :decorated_collection
-          end
-        end
-
-        context "when :with option was not given" do
-          context "when the collection itself is decoratable" do
-            before { associated.stub decorator_class: ProductsDecorator }
-
-            it "infers the decorator" do
-              ProductsDecorator.should_receive(:decorate).with(associated, context: context).and_return(:decorated_collection)
-              expect(decorated_association.call).to be :decorated_collection
-            end
-          end
-
-          context "when the collection is not decoratable" do
-            it "uses a CollectionDecorator of inferred decorators" do
-              CollectionDecorator.should_receive(:decorate).with(associated, context: context).and_return(:decorated_collection)
-              expect(decorated_association.call).to be :decorated_collection
-            end
-          end
+      describe ":with option" do
+        it "defaults to nil" do
+          Factory.should_receive(:new).with(with: nil, context: anything())
+          DecoratedAssociation.new(double, :association, {})
         end
       end
 
-      context "with a scope" do
-        let(:options) { {scope: :foo} }
-        let(:associated) { double(foo: scoped) }
-        let(:scoped) { Product.new }
-
-        it "applies the scope before decoration" do
-          expect(decorated_association.call.source).to be scoped
+      describe ":context option" do
+        it "defaults to the identity function" do
+          Factory.should_receive(:new).with do |options|
+            options[:context].call(:anything) == :anything
+          end
+          DecoratedAssociation.new(double, :association, {})
         end
       end
     end
 
-    describe "#context" do
-      let(:owner_context) { {some: "context"} }
-      let(:options) { {} }
-      let(:owner) { double(context: owner_context) }
-      let(:decorated_association) { DecoratedAssociation.new(owner, :association, options) }
-
-      context "when :context option was given" do
-        let(:options) { {context: context} }
-
-        context "and is callable" do
-          let(:context) { ->(*){ :dynamic_context } }
-
-          it "calls it with the owner's context" do
-            context.should_receive(:call).with(owner_context)
-            decorated_association.context
-          end
-
-          it "returns the lambda's return value" do
-            expect(decorated_association.context).to be :dynamic_context
-          end
-        end
-
-        context "and is not callable" do
-          let(:context) { {other: "context"} }
-
-          it "returns the specified value" do
-            expect(decorated_association.context).to be context
-          end
-        end
+    describe "#call" do
+      it "calls the factory" do
+        factory = double
+        Factory.stub new: factory
+        associated = double
+        owner_context = {foo: "bar"}
+        source = double(association: associated)
+        owner = double(source: source, context: owner_context)
+        decorated_association = DecoratedAssociation.new(owner, :association, {})
+        decorated = double
+
+        factory.should_receive(:decorate).with(associated, context_args: owner_context).and_return(decorated)
+        expect(decorated_association.call).to be decorated
       end
 
-      context "when :context option was not given" do
-        it "returns the owner's context" do
-          expect(decorated_association.context).to be owner_context
-        end
+      it "memoizes" do
+        factory = double
+        Factory.stub new: factory
+        owner = double(source: double(association: double), context: {})
+        decorated_association = DecoratedAssociation.new(owner, :association, {})
+        decorated = double
 
-        it "returns the new context if the owner's context changes" do
-          new_context = {other: "context"}
-          owner.stub context: new_context
+        factory.should_receive(:decorate).once.and_return(decorated)
+        expect(decorated_association.call).to be decorated
+        expect(decorated_association.call).to be decorated
+      end
 
-          expect(decorated_association.context).to be new_context
+      context "when the :scope option was given" do
+        it "applies the scope before decoration" do
+          factory = double
+          Factory.stub new: factory
+          scoped = double
+          source = double(association: double(applied_scope: scoped))
+          owner = double(source: source, context: {})
+          decorated_association = DecoratedAssociation.new(owner, :association, scope: :applied_scope)
+          decorated = double
+
+          factory.should_receive(:decorate).with(scoped, anything()).and_return(decorated)
+          expect(decorated_association.call).to be decorated
         end
       end
     end

spec/draper/decorates_assigned_spec.rb

@@ -49,7 +49,7 @@ def self.helper_methods
           controller = controller_class.new
           controller.instance_variable_set "@article", source
 
-          factory.should_receive(:decorate).with(source).and_return(:decorated)
+          factory.should_receive(:decorate).with(source, context_args: controller).and_return(:decorated)
           expect(controller.article).to be :decorated
         end
 

spec/draper/factory_spec.rb

@@ -104,6 +104,48 @@ module Draper
         decorator.should_receive(:call).with(source, options).and_return(:decorated)
         expect(worker.call(options)).to be :decorated
       end
+
+      context "when the :context option is callable" do
+        it "calls it" do
+          worker = Factory::Worker.new(double, double)
+          decorator = ->(*){}
+          worker.stub decorator: decorator
+          context = {foo: "bar"}
+
+          decorator.should_receive(:call).with(anything(), context: context)
+          worker.call(context: ->{ context })
+        end
+
+        it "receives arguments from the :context_args option" do
+          worker = Factory::Worker.new(double, double)
+          worker.stub decorator: ->(*){}
+          context = ->{}
+
+          context.should_receive(:call).with(:foo, :bar)
+          worker.call(context: context, context_args: [:foo, :bar])
+        end
+      end
+
+      context "when the :context option is not callable" do
+        it "doesn't call it" do
+          worker = Factory::Worker.new(double, double)
+          decorator = ->(*){}
+          worker.stub decorator: decorator
+          context = {foo: "bar"}
+
+          decorator.should_receive(:call).with(anything(), context: context)
+          worker.call(context: context)
+        end
+      end
+
+      it "does not pass the :context_args option to the decorator" do
+        worker = Factory::Worker.new(double, double)
+        decorator = ->(*){}
+        worker.stub decorator: decorator
+
+        decorator.should_receive(:call).with(anything(), foo: "bar")
+        worker.call(foo: "bar", context_args: [])
+      end
     end
 
     describe "#decorator" do