Add parent option (#1073)

docs/CHANGELOG.md

@@ -7,6 +7,11 @@ title: Changelog
 
 ## main
 
+* Add `--parent` generator option to specify the parent class.
+* Add config option `config.view_component.component_parent_class` to change it project-wide.
+
+    *Hans Lemuet*
+
 * Update docs to add example for using Devise helpers in tests.
 
     *Matthew Rider*

docs/api.md

@@ -74,6 +74,14 @@ _Will be removed in v3.0.0._
 
 ## Configuration
 
+### #component_parent_class
+
+Parent class for generated components
+
+    config.view_component.component_parent_class = "MyBaseComponent"
+
+Defaults to "ApplicationComponent" if defined, "ViewComponent::Base" otherwise.
+
 ### #default_preview_layout
 
 Set a custom default layout used for preview index and individual previews:

docs/guide/generators.md

@@ -105,6 +105,22 @@ bin/rails generate component Example title --inline
       invoke  erb
 ```
 
+### Specify the parent class
+
+By default, `ApplicationComponent` is used if defined, `ViewComponent::Base` otherwise.
+
+```console
+bin/rails generate component Example title content --parent MyBaseComponent
+
+      create  app/components/example_component.rb
+      invoke  test_unit
+      create    test/components/example_component_test.rb
+      invoke  erb
+      create    app/components/example_component.html.erb
+```
+
+To always use your own parent class, set `config.view_component.component_parent_class = "MyBaseComponent"`.
+
 ### Skip collision check
 
 The generator prevents naming collisions with existing components. To skip this check and force the generator to run, use the `--skip-collision-check` or `--force` option.

lib/rails/generators/component/component_generator.rb

@@ -12,6 +12,7 @@ module Rails
       argument :attributes, type: :array, default: [], banner: "attribute"
       check_class_collision suffix: "Component"
       class_option :inline, type: :boolean, default: false
+      class_option :parent, type: :string, desc: "The parent class for the generated component"
       class_option :stimulus, type: :boolean, default: ViewComponent::Base.generate_stimulus_controller
       class_option :sidecar, type: :boolean, default: false
 
@@ -32,7 +33,13 @@ module Rails
       private
 
       def parent_class
-        defined?(ApplicationComponent) ? "ApplicationComponent" : "ViewComponent::Base"
+        if options[:parent]
+          options[:parent]
+        elsif defined?(ApplicationComponent)
+          ApplicationComponent
+        else
+          ViewComponent::Base.component_parent_class
+        end
       end
 
       def initialize_signature

lib/view_component/base.rb

@@ -281,6 +281,15 @@ module ViewComponent
     # Defaults to "app/components".
     mattr_accessor :view_component_path, instance_writer: false, default: "app/components"
 
+    # Parent class for generated components
+    #
+    #     config.view_component.component_parent_class = "MyBaseComponent"
+    #
+    # Defaults to "ApplicationComponent" if defined, "ViewComponent::Base" otherwise.
+    mattr_accessor :component_parent_class,
+                   instance_writer: false,
+                   default: "ViewComponent::Base"
+
     class << self
       # @private
       attr_accessor :source_location, :virtual_path

test/generators/component_generator_test.rb

@@ -17,7 +17,7 @@ class ComponentGeneratorTest < Rails::Generators::TestCase
     run_generator
 
     assert_file "app/components/user_component.rb" do |component|
-      assert_match(/class UserComponent < /, component)
+      assert_match(/class UserComponent < ViewComponent::Base/, component)
       assert_no_match(/def initialize/, component)
     end
   end
@@ -83,6 +83,14 @@ class ComponentGeneratorTest < Rails::Generators::TestCase
     assert_no_file "component.html.erb"
   end
 
+  def test_component_with_parent
+    run_generator %w[user --parent MyBaseComponent]
+
+    assert_file "app/components/user_component.rb" do |component|
+      assert_match(/class UserComponent < MyBaseComponent/, component)
+    end
+  end
+
   def test_component_with_namespace
     run_generator %w[admins/user]
 
@@ -136,6 +144,26 @@ class ComponentGeneratorTest < Rails::Generators::TestCase
     end
   end
 
+  def test_generating_components_with_application_component_class
+    with_application_component_class do
+      run_generator %w[user]
+
+      assert_file "app/components/user_component.rb" do |component|
+        assert_match(/class UserComponent < ApplicationComponent/, component)
+      end
+    end
+  end
+
+  def test_generating_components_with_custom_component_parent_class
+    with_custom_component_parent_class("MyBaseComponent") do
+      run_generator %w[user]
+
+      assert_file "app/components/user_component.rb" do |component|
+        assert_match(/class UserComponent < MyBaseComponent/, component)
+      end
+    end
+  end
+
   def test_component_with_stimulus
     run_generator %w[user --stimulus]
 

test/test_helper.rb

@@ -60,6 +60,21 @@ ensure
   ViewComponent::Base.view_component_path = old_value
 end
 
+def with_custom_component_parent_class(new_value)
+  old_value = ViewComponent::Base.component_parent_class
+  ViewComponent::Base.component_parent_class = new_value
+  yield
+ensure
+  ViewComponent::Base.component_parent_class = old_value
+end
+
+def with_application_component_class
+  Object.const_set("ApplicationComponent", Class.new(Object))
+  yield
+ensure
+  Object.send(:remove_const, :ApplicationComponent)
+end
+
 def with_new_cache
   begin
     old_cache = ViewComponent::CompileCache.cache