Allow injecting a custom renderer class

.rubocop.yml

@@ -55,9 +55,6 @@ Naming/PredicateName:
 Naming/VariableName:
   Enabled: true
 
-Layout/AlignParameters:
-  Enabled: true
-
 Layout/BlockAlignment:
   Enabled: true
   EnforcedStyleAlignWith: start_of_block
@@ -89,6 +86,9 @@ Layout/EmptyLines:
 Layout/EmptyLinesAroundAccessModifier:
   Enabled: true
 
+Layout/ParameterAlignment:
+  Enabled: true
+
 Layout/SpaceAroundBlockParameters:
   Enabled: true
 

README.md

@@ -31,6 +31,7 @@ This gem has been inspired by our Rails development practices at [Ouvrages](http
   - [Helpers](#helpers)
   - [Component partials](#component-partials)
   - [Namespacing components](#namespacing-components)
+  - [Custom Renderer](#custom-renderer)
   - [Stimulus integration](#stimulus-integration)
   - [Internationalization](#internationalization)
     - [Available locales configuration](#available-locales-configuration)
@@ -182,7 +183,7 @@ Each component comes with a Ruby `module`. You can use it to set properties:
 
 module ButtonComponent
   extend ComponentHelper
-  
+
   property :href, required: true
   property :text, default: 'My button'
 end
@@ -204,7 +205,7 @@ If your partial becomes too complex and you want to extract logic from it, you m
 
 module ButtonComponent
   extend ComponentHelper
-  
+
   property :href, required: true
   property :text, default: 'My button'
 
@@ -257,6 +258,45 @@ rails generate component admin/header
 
 This will create the component in an `admin` folder, and name its Ruby module `AdminHeaderComponent`.
 
+### Custom renderer
+
+Komponent supports using a custom renderer if you want to customize rendering behaviour.
+
+For instance, you can use this to add I18n to your properties:
+
+```rb
+# frontend/components/button/button_component.rb
+
+module ButtonComponent
+  extend ComponentHelper
+
+  property :text, default: 'My button', custom_localize: true
+end
+```
+
+```rb
+# somwhere inside your app, e.g. app/models/localized_component_renderer.rb
+
+class LocalizedComponentRenderer < Komponent::ComponentRenderer
+  def assign_property_value(property_name, property_options, locals)
+    if property_options[:custom_localize]
+      original_value = locals[property_name]
+      locals[property_name] = I18n.t(property_name, default: original_value)
+    else
+      super
+    end
+  end
+end
+```
+
+```slim
+/ app/views/pages/home.html.slim
+
+/ Use custom renderer class
+= component "button", { text: 'Click here' }, renderer: LocalizedComponentRenderer
+```
+
+
 ### Stimulus integration
 
 Komponent supports [Stimulus](https://github.com/stimulusjs/stimulus) >= 1.0.

lib/komponent/component_renderer.rb

@@ -36,6 +36,16 @@ def render(component, locals = {}, options = {}, &block)
       end
     end
 
+    def assign_property_value(property_name, property_options, locals)
+      return if locals.has_key?(property_name)
+
+      if property_options.has_key?(:default)
+        locals[property_name] = property_options[:default]
+      elsif property_options[:required]
+        raise "Missing required component parameter: #{property_name}"
+      end
+    end
+
     private
 
     def _render(component, locals = {}, options = {}, &block)
@@ -53,20 +63,14 @@ def _render(component, locals = {}, options = {}, &block)
 
       @lookup_context.prefixes = ["components/#{component}"]
 
-      @context.instance_eval do
-        if component_module.respond_to?(:properties)
-          locals = locals.dup
-          component_module.properties.each do |name, options|
-            unless locals.has_key?(name)
-              if options.has_key?(:default)
-                locals[name] = options[:default]
-              elsif options[:required]
-                raise "Missing required component parameter: #{name}"
-              end
-            end
-          end
+      if component_module.respond_to?(:properties)
+        locals = locals.dup
+        component_module.properties.each do |name, options|
+          assign_property_value(name, options, locals)
         end
+      end
 
+      @context.instance_eval do
         locals.each do |name, value|
           instance_variable_set(:"@#{name}", locals[name])
         end

lib/komponent/komponent_helper.rb

@@ -5,7 +5,8 @@
 module KomponentHelper
   def component(component_name, locals = {}, options = {}, &block)
     captured_block = proc { |args| capture(args, &block) } if block_given?
-    Komponent::ComponentRenderer.new(
+    renderer_klass = options.delete(:renderer) || Komponent::ComponentRenderer
+    renderer_klass.new(
       controller,
       view_flow || (view && view.view_flow),
     ).render(

test/komponent/komponent_helper_test.rb

@@ -9,6 +9,18 @@ def test_helper_raises_component_missing_error
     end
   end
 
+  def test_inject_custom_renderer
+    custom_renderer_klass = Class.new(Komponent::ComponentRenderer) do
+      def render(*args)
+        'custom_render_method'
+      end
+    end
+
+    assert_equal \
+      'custom_render_method',
+      component('world', {}, renderer: custom_renderer_klass)
+  end
+
   def test_helper_renders_namespaced_component
     assert_equal \
       %(<div class="namespaced-button">namespaced_button_component</div>),