Lazy load entity and repository

Additonally, adding validation for presence of entity and repository for load!

lib/lotus/model/mapping.rb

@@ -19,6 +19,30 @@ def initialize(name)
           super("Cannot find collection: #{ name }")
         end
       end
+
+      # Invalid entity error.
+      #
+      # It gets raised when the application tries to access to a existing
+      # entity.
+      #
+      # @since 0.2.0
+      class EntityNotFound < ::StandardError
+        def initialize(name)
+          super("Cannot find class for entity: #{ name }")
+        end
+      end
+
+      # Invalid repository error.
+      #
+      # It gets raised when the application tries to access to a existing
+      # repository.
+      #
+      # @since 0.2.0
+      class RepositoryNotFound < ::StandardError
+        def initialize(name)
+          super("Cannot find class for repository: #{ name }")
+        end
+      end
     end
   end
 end

lib/lotus/model/mapping/collection.rb

@@ -88,7 +88,9 @@ class ::Boolean
         #
         # @see Lotus::Model::Mapper#collection
         def initialize(name, coercer_class, &blk)
-          @name, @coercer_class, @attributes = name, coercer_class, {}
+          @name = name
+          @coercer_class = coercer_class
+          @attributes = {}
           instance_eval(&blk) if block_given?
         end
 
@@ -126,9 +128,11 @@ def initialize(name, coercer_class, &blk)
         #   mapper.entity #=> Article
         #
         def entity(klass = nil)
-          @entity = klass if klass
-
-          Utils::Class.load!(@entity) if @entity
+          if klass
+            @entity = klass
+          else
+            @entity
+          end
         end
 
         # Defines the repository that interacts with this collection.
@@ -170,8 +174,6 @@ def repository(klass = nil)
           else
             @repository ||= default_repository_klass
           end
-
-          Utils::Class.load!(@repository)
         end
 
         # Defines the identity for a collection.
@@ -386,21 +388,52 @@ def deserialize_attribute(attribute, value)
         # @api private
         # @since 0.1.0
         def load!
-          @coercer = coercer_class.new(self)
-          configure_repository!
+          _load_entity!
+          _load_repository!
+          _load_coercer!
+
+          _configure_repository!
         end
 
         private
+
         # Assigns a repository to an entity
         #
         # @see Lotus::Repository
         #
         # @api private
         # @since 0.1.0
-        def configure_repository!
+        def _configure_repository!
           repository.collection = name
-          repository.adapter = adapter
-          rescue NameError
+          repository.adapter = adapter if adapter
+        end
+
+        # Convert repository string to repository class
+        #
+        # @api private
+        # @since 0.2.0
+        def _load_repository!
+          @repository = Utils::Class.load!(repository)
+        rescue NameError
+          raise Lotus::Model::Mapping::RepositoryNotFound.new(repository.to_s)
+        end
+
+        # Convert entity string to entity class
+        #
+        # @api private
+        # @since 0.2.0
+        def _load_entity!
+          @entity = Utils::Class.load!(entity)
+        rescue NameError
+          raise Lotus::Model::Mapping::EntityNotFound.new(entity.to_s)
+        end
+
+        # Load coercer
+        #
+        # @api private
+        # @since 0.1.0
+        def _load_coercer!
+          @coercer = coercer_class.new(self)
         end
 
         # Retrieves the default repository class

test/model/adapters/memory_adapter_test.rb

@@ -6,10 +6,18 @@
       include Lotus::Entity
     end
 
+    class TestUserRepository
+      include Lotus::Repository
+    end
+
     TestDevice = Struct.new(:id) do
       include Lotus::Entity
     end
 
+    class TestDeviceRepository
+      include Lotus::Repository
+    end
+
     @mapper = Lotus::Model::Mapper.new do
       collection :users do
         entity TestUser
@@ -31,7 +39,9 @@
 
   after do
     Object.send(:remove_const, :TestUser)
+    Object.send(:remove_const, :TestUserRepository)
     Object.send(:remove_const, :TestDevice)
+    Object.send(:remove_const, :TestDeviceRepository)
   end
 
   let(:collection) { :users }

test/model/adapters/sql_adapter_test.rb

@@ -6,10 +6,18 @@
       include Lotus::Entity
     end
 
+    class TestUserRepository
+      include Lotus::Repository
+    end
+
     TestDevice = Struct.new(:id) do
       include Lotus::Entity
     end
 
+    class TestDeviceRepository
+      include Lotus::Repository
+    end
+
     @mapper = Lotus::Model::Mapper.new do
       collection :users do
         entity TestUser
@@ -32,7 +40,9 @@
 
   after do
     Object.send(:remove_const, :TestUser)
+    Object.send(:remove_const, :TestUserRepository)
     Object.send(:remove_const, :TestDevice)
+    Object.send(:remove_const, :TestDeviceRepository)
   end
 
   let(:collection) { :users }

test/model/mapping/collection_test.rb

@@ -46,8 +46,8 @@
           @collection.entity('User')
         end
 
-        it 'sets the value and classify the value' do
-          @collection.entity.must_equal User
+        it 'sets the value' do
+          @collection.entity.must_equal 'User'
         end
       end
     end
@@ -80,26 +80,15 @@
           @collection.repository('CustomUserRepository')
         end
 
-        it 'sets the value and classify the value' do
-          @collection.repository.must_equal CustomUserRepository
+        it 'sets the value' do
+          @collection.repository.must_equal 'CustomUserRepository'
         end
       end
     end
 
     describe 'when a value is not given' do
       it 'returns the default value' do
-        @collection.repository.must_equal UserRepository
-      end
-
-      describe 'when repository class is not found' do
-        before do
-          class KlassWithoutRepository; end
-          @collection.entity KlassWithoutRepository
-        end
-
-        it 'raises NameError' do
-          -> { @collection.repository }.must_raise NameError
-        end
+        @collection.repository.must_equal 'UserRepository'
       end
     end
   end
@@ -140,11 +129,20 @@ class KlassWithoutRepository; end
   describe '#load!' do
     before do
       @adapter = Lotus::Model::Adapters::SqlAdapter.new(nil, SQLITE_CONNECTION_STRING)
-      @collection.entity(User)
+      @collection.entity('User')
+      @collection.repository('UserRepository')
       @collection.adapter = @adapter
       @collection.load!
     end
 
+    it 'converts entity to class' do
+      @collection.entity.must_equal User
+    end
+
+    it 'converts repository to class' do
+      @collection.repository.must_equal UserRepository
+    end
+
     it 'sets up repository' do
       UserRepository.collection.must_equal :users
       UserRepository.instance_variable_get(:@adapter).must_equal @adapter
@@ -153,5 +151,29 @@ class KlassWithoutRepository; end
     it 'instantiates coercer' do
       @collection.instance_variable_get(:@coercer).must_be_instance_of Lotus::Model::Mapping::Coercer
     end
+
+    describe 'when entity class does not exist' do
+      before do
+        @collection = Lotus::Model::Mapping::Collection.new(:users, Lotus::Model::Mapping::Coercer)
+        @collection.entity('NonExistingUser')
+        @collection.repository('UserRepository')
+      end
+
+      it 'raises error' do
+        -> { @collection.load! }.must_raise(Lotus::Model::Mapping::EntityNotFound)
+      end
+    end
+
+    describe 'when repository class does not exist' do
+      before do
+        @collection = Lotus::Model::Mapping::Collection.new(:users, Lotus::Model::Mapping::Coercer)
+        @collection.entity('User')
+        @collection.repository('NonExistingUserRepository')
+      end
+
+      it 'raises error' do
+        -> { @collection.load! }.must_raise(Lotus::Model::Mapping::RepositoryNotFound)
+      end
+    end
   end
 end