From 3a214b8af44d5fcacd242c1b3280db5084424df2 Mon Sep 17 00:00:00 2001
From: Michal Cichra <mikz@users.noreply.github.com>
Date: Fri, 17 Oct 2025 11:41:32 +0200
Subject: [PATCH] Remove dependency on the Rails module

Some parts of the code guard against undefined Rails module,
but some parts do that in unsafe manner.

Good example: `defined?(Rails.env) && Rails.env`
Bad example: `defined?(Rails) && Rails.env`

There are gems, that define `module Rails` to extend it, but then it is
incomplete and causes failures.

This change unifies accessing Rails module with proper `defines?`
guarding against incomplete definition of the Rails module.
---
 docs/CHANGELOG.md                | 3 +++
 lib/view_component.rb            | 2 +-
 lib/view_component/base.rb       | 6 +++---
 lib/view_component/collection.rb | 2 +-
 lib/view_component/config.rb     | 2 +-
 5 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index f63af3faf..9c7715760 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -13,6 +13,9 @@ nav_order: 6
 * Add Carwow to list of companies using ViewComponent.
 
     *Tom Lord*
+* ViewComponent now works without `rails` and `railties` gems loaded.
+
+    *Michal Cichra*
 
 ## 4.0.2
 
diff --git a/lib/view_component.rb b/lib/view_component.rb
index 3db9728ba..a67288011 100644
--- a/lib/view_component.rb
+++ b/lib/view_component.rb
@@ -16,7 +16,7 @@ module ViewComponent
   autoload :Preview
   autoload :Translatable
 
-  if Rails.env.test?
+  if defined?(Rails.env) && Rails.env.test?
     autoload :TestHelpers
     autoload :SystemSpecHelpers
     autoload :SystemTestHelpers
diff --git a/lib/view_component/base.rb b/lib/view_component/base.rb
index 97ba41815..854eea910 100644
--- a/lib/view_component/base.rb
+++ b/lib/view_component/base.rb
@@ -47,7 +47,7 @@ def config
     end
 
     include ActionView::Helpers
-    include Rails.application.routes.url_helpers if defined?(Rails) && Rails.application
+    include Rails.application.routes.url_helpers if defined?(Rails.application.routes)
     include ERB::Escape
     include ActiveSupport::CoreExt::ERBUtil
 
@@ -302,7 +302,7 @@ def helpers
       @__vc_helpers ||= __vc_original_view_context || controller.view_context
     end
 
-    if ::Rails.env.development? || ::Rails.env.test?
+    if defined?(Rails.env) && (::Rails.env.development? || ::Rails.env.test?)
       # @private
       def method_missing(method_name, *args) # rubocop:disable Style/MissingRespondToMissing
         super
@@ -331,7 +331,7 @@ def view_cache_dependencies
       []
     end
 
-    if Rails::VERSION::MAJOR == 7 && Rails::VERSION::MINOR == 1
+    if defined?(Rails::VERSION) && (Rails::VERSION::MAJOR == 7 && Rails::VERSION::MINOR == 1)
       # Rails expects us to define `format` on all renderables,
       # but we do not know the `format` of a ViewComponent until runtime.
       def format
diff --git a/lib/view_component/collection.rb b/lib/view_component/collection.rb
index c53f1f1af..7a3f8d42e 100644
--- a/lib/view_component/collection.rb
+++ b/lib/view_component/collection.rb
@@ -20,7 +20,7 @@ def each(&block)
       components.each(&block)
     end
 
-    if Rails::VERSION::MAJOR == 7 && Rails::VERSION::MINOR == 1
+    if defined?(Rails::VERSION) && (Rails::VERSION::MAJOR == 7 && Rails::VERSION::MINOR == 1)
       # Rails expects us to define `format` on all renderables,
       # but we do not know the `format` of a ViewComponent until runtime.
       def format
diff --git a/lib/view_component/config.rb b/lib/view_component/config.rb
index d3c26f57e..204791b88 100644
--- a/lib/view_component/config.rb
+++ b/lib/view_component/config.rb
@@ -163,7 +163,7 @@ def default_previews_options
         options = ActiveSupport::OrderedOptions.new
         options.controller = "ViewComponentsController"
         options.route = "/rails/view_components"
-        options.enabled = Rails.env.development? || Rails.env.test?
+        options.enabled = defined?(Rails.env) && (Rails.env.development? || Rails.env.test?)
         options.default_layout = nil
         options.paths = default_preview_paths
         options