Fixed problem with sprockets being the default during installation.

.github/workflows/test.yml

@@ -12,7 +12,7 @@ jobs:
         gemfile: [gemfiles/rails_7.0.gemfile]
         orm: [active_record]
         adapter: [sqlite3]
-        asset: [webpacker]
+        asset: [webpack]
         include:
           - ruby: 2.6
             gemfile: gemfiles/rails_6.0.gemfile
@@ -33,7 +33,7 @@ jobs:
             gemfile: gemfiles/rails_7.0.gemfile
             orm: active_record
             adapter: mysql2
-            asset: sprockets
+            asset: importmap
           - ruby: "3.0"
             gemfile: gemfiles/rails_7.0.gemfile
             orm: active_record
@@ -102,13 +102,18 @@ jobs:
       - name: Setup application
         env:
           BUNDLE_GEMFILE: ../../${{ matrix.gemfile }}
+          CI_ASSET: ${{ matrix.asset }}
           CI_DB_ADAPTER: ${{ matrix.adapter }}
           RAILS_ENV: test
         run: |
           yarn install
           cd spec/dummy_app
           bundle exec rake rails_admin:prepare_ci_env db:create db:migrate
           yarn install
+          case "$CI_ASSET" in
+          "webpack" ) yarn build && yarn build:css ;;
+          "importmap" ) yarn build:css ;;
+          esac
           cd ../../
       - name: Run tests
         run: bundle exec rspec

.gitignore

@@ -26,6 +26,6 @@ spec/dummy_app/db/*.sqlite3-journal
 spec/dummy_app/db/schema.rb
 spec/dummy_app/log/*.log
 spec/dummy_app/public/uploads
-spec/dummy_app/Gemfile.lock
+spec/dummy_app/Gemfile*.lock
 tmp/**/*
 nbproject

.prettierignore

@@ -1,5 +1,6 @@
 coverage
 lib/generators/rails_admin/templates
+spec/dummy_app/app/assets/builds
 spec/dummy_app/public
 spec/dummy_app/tmp
 spec/support/jquery.simulate.drag-sortable.js

Appraisals

@@ -69,6 +69,7 @@ end
 
 appraise 'rails-7.0' do
   gem 'rails', '~> 7.0.0'
+  gem 'importmap-rails', require: false
   gem 'sassc-rails', '~> 2.1'
   gem 'devise', '~> 4.8'
 

app/views/layouts/rails_admin/_head.html.erb

@@ -4,14 +4,26 @@
 <meta content="NONE,NOARCHIVE" name="robots"/>
 <%= csrf_meta_tag %>
 <% case RailsAdmin::config.asset_source
-   when :webpacker %>
-  <%= stylesheet_pack_tag "rails_admin" %>
-  <%= javascript_pack_tag "rails_admin", async: true %>
-<% when :webpack, :sprockets %>
+   when :sprockets %>
   <% handle_asset_dependency_error do %>
     <%= stylesheet_link_tag "rails_admin/application.css", media: :all %>
     <%= javascript_include_tag "rails_admin/application.js", async: true %>
   <% end %>
+<% when :webpacker %>
+  <%= stylesheet_pack_tag "rails_admin" %>
+  <%= javascript_pack_tag "rails_admin", async: true %>
+<% when :importmap %>
+  <%= stylesheet_link_tag "rails_admin.css", media: :all %>
+  <%= javascript_inline_importmap_tag(RailsAdmin::Engine.importmap.to_json(resolver: self)) %>
+  <%= javascript_importmap_module_preload_tags(RailsAdmin::Engine.importmap) %>
+  <%= javascript_importmap_shim_nonce_configuration_tag %>
+  <%= javascript_importmap_shim_tag %>
+  <%= # Preload jQuery and make it global, unless jQuery UI fails to initialize
+      tag.script "import jQuery from 'jquery'; window.jQuery = jQuery;".html_safe, type: "module" %>
+  <%= javascript_import_module_tag 'rails_admin' %>
+<% when :webpack %>
+  <%= stylesheet_link_tag "rails_admin.css", media: :all %>
+  <%= javascript_include_tag "rails_admin.js", async: true %>
 <% else
      raise "Unknown asset_source: #{RailsAdmin::config.asset_source}"
    end %>

gemfiles/rails_7.0.gemfile

@@ -7,6 +7,7 @@ gem "devise", "~> 4.8"
 gem "rails", "~> 7.0.0"
 gem "webpacker", require: false
 gem "webrick", "~> 1.7"
+gem "importmap-rails", require: false
 gem "sassc-rails", "~> 2.1"
 
 group :active_record do

lib/generators/rails_admin/importmap_formatter.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+require 'importmap/packager'
+
+module RailsAdmin
+  class ImportmapFormatter
+    attr_reader :packager
+
+    def initialize(path = 'confing/importmap.rails_admin.rb')
+      @packager = Importmap::Packager.new(path)
+    end
+
+    def format
+      imports = packager.import("rails_admin@#{RailsAdmin::Version.js}")
+
+      # Use ESM compatible version to work around https://github.com/cljsjs/packages/issues/1579
+      imports['@popperjs/core'].gsub!('lib/index.js', 'dist/esm/popper.js')
+
+      # Tidy up jQuery UI dependencies
+      jquery_uis = imports.keys.filter { |key, _| key =~ /jquery-ui/ }
+      imports['jquery-ui/'] = imports[jquery_uis.first].gsub(%r{(@[^/@]+)/[^@]+$}, '\1/')
+      imports.reject! { |key, _| jquery_uis.include? key }
+
+      pins = ['pin "rails_admin", preload: true', packager.pin_for('rails_admin/src/rails_admin/base', imports.delete('rails_admin'))]
+      (pins + imports.map { |package, url| packager.pin_for(package, url) }).join("\n")
+    end
+  end
+end

lib/generators/rails_admin/install_generator.rb

@@ -10,7 +10,7 @@ class InstallGenerator < Rails::Generators::Base
     include Generators::Utils::InstanceMethods
 
     argument :_namespace, type: :string, required: false, desc: 'RailsAdmin url namespace'
-    class_option :asset, type: :string, required: false, default: nil, desc: 'Asset delivery method [options: webpacker, sprockets]'
+    class_option :asset, type: :string, required: false, default: nil, desc: 'Asset delivery method [options: webpacker, webpack, sprockets, importmap]'
     desc 'RailsAdmin installation generator'
 
     def install
@@ -29,10 +29,14 @@ def install
       case asset
       when 'webpack'
         configure_for_webpack
+      when 'importmap'
+        configure_for_importmap
       when 'webpacker'
         configure_for_webpacker5
       when 'sprockets'
         configure_for_sprockets
+      else
+        raise "Unknown asset source: #{asset}"
       end
     end
 
@@ -41,11 +45,7 @@ def install
     def asset
       return options['asset'] if options['asset']
 
-      if defined?(Webpacker)
-        'webpacker'
-      else
-        'sprockets'
-      end
+      RailsAdmin::Config::asset_source.to_s
     end
 
     def configure_for_sprockets
@@ -54,17 +54,66 @@ def configure_for_sprockets
 
     def configure_for_webpacker5
       run "yarn add rails_admin@#{RailsAdmin::Version.js}"
-      @scss_relative_dir = '../stylesheets/'
-      template 'rails_admin.js.erb', 'app/javascript/packs/rails_admin.js'
-      template 'rails_admin.scss', 'app/javascript/stylesheets/rails_admin.scss'
+      template 'rails_admin.webpacker.js', 'app/javascript/packs/rails_admin.js'
+      template 'rails_admin.scss.erb', 'app/javascript/stylesheets/rails_admin.scss'
     end
 
     def configure_for_webpack
-      run "yarn add rails_admin@#{RailsAdmin::Version.js} css-loader mini-css-extract-plugin sass sass-loader"
-      @scss_relative_dir = './'
-      template 'rails_admin.js.erb', 'app/javascript/rails_admin.js'
-      template 'rails_admin.scss', 'app/javascript/rails_admin.scss'
-      template 'webpack.config.js', 'webpack.config.js'
+      run "yarn add rails_admin@#{RailsAdmin::Version.js}"
+      template 'rails_admin.js', 'app/javascript/rails_admin.js'
+      webpack_config = File.join(destination_root, 'webpack.config.js')
+      marker = %r{application: ["']./app/javascript/application.js["']}
+      if File.exist?(webpack_config) && File.read(webpack_config) =~ marker
+        insert_into_file 'webpack.config.js', %(,\n    rails_admin: "./app/javascript/rails_admin.js"), after: marker
+      else
+        say 'Add `rails_admin: "./app/javascript/rails_admin.js"` to the entry section in your webpack.config.js.', :red
+      end
+      setup_css({'build' => 'webpack --config webpack.config.js'})
+    end
+
+    def configure_for_importmap
+      run "yarn add rails_admin@#{RailsAdmin::Version.js}"
+      template 'rails_admin.js', 'app/javascript/rails_admin.js'
+      require_relative 'importmap_formatter'
+      add_file 'config/importmap.rails_admin.rb', ImportmapFormatter.new.format
+      setup_css
+    end
+
+    def setup_css(additional_script_entries = {})
+      gem 'cssbundling-rails' unless defined?(Cssbundling) == 'constant'
+      rake 'css:install:sass'
+
+      @fa_font_path = '.'
+      template 'rails_admin.scss.erb', 'app/assets/stylesheets/rails_admin.scss'
+      asset_config = %{Rails.application.config.assets.paths << Rails.root.join("node_modules/@fortawesome/fontawesome-free/webfonts")\n}
+      if File.exist? File.join(destination_root, 'config/initializers/assets.rb')
+        append_to_file 'config/initializers/assets.rb', asset_config
+      else
+        add_file 'config/initializers/assets.rb', asset_config
+      end
+      add_scripts(additional_script_entries.merge({'build:css' => 'sass ./app/assets/stylesheets/rails_admin.scss:./app/assets/builds/rails_admin.css --no-source-map --load-path=node_modules'}))
+    end
+
+    def add_scripts(entries)
+      display 'Add scripts to package.json'
+      package = begin
+        JSON.parse(File.read(File.join(destination_root, 'package.json')))
+      rescue Errno::ENOENT, JSON::ParserError
+        {}
+      end
+      if package['scripts'] && (package['scripts'].keys & entries.keys).any?
+        say <<-MESSAGE.gsub(/^ {10}/, ''), :red
+          You need to merge "scripts": #{JSON.pretty_generate(entries)} into the existing scripts in your package.json .
+          Taking 'build:css' as an example, if you're already have application.sass.css for the sass build, the resulting script would look like:
+            sass ./app/assets/stylesheets/application.sass.scss:./app/assets/builds/application.css ./app/assets/stylesheets/rails_admin.scss:./app/assets/builds/rails_admin.css --no-source-map --load-path=node_modules
+        MESSAGE
+      else
+        package['scripts'] ||= {}
+        entries.each do |entry, build_script|
+          package['scripts'][entry] = build_script
+        end
+        add_file 'package.json', JSON.pretty_generate(package)
+      end
     end
   end
 end

lib/generators/rails_admin/templates/rails_admin.js

@@ -0,0 +1 @@
+import "rails_admin/src/rails_admin/base";

lib/generators/rails_admin/templates/rails_admin.scss.erb

@@ -0,0 +1 @@
+<%= instance_variable_defined?(:@fa_font_path) ? %{$fa-font-path: "#{@fa_font_path}";\n} : '' %>@import "rails_admin/src/rails_admin/styles/base";

lib/generators/rails_admin/templates/rails_admin.webpacker.js

@@ -0,0 +1,2 @@
+import "rails_admin/src/rails_admin/base";
+import "../stylesheets/rails_admin.scss";

lib/rails_admin/config.rb

@@ -260,14 +260,15 @@ def model(entity, &block)
       end
 
       def asset_source
-        @asset_source ||=
-          begin
-            warn <<~MSG
-              [Warning] After upgrading RailsAdmin to 3.x you haven't set asset_source yet, using :sprockets as the default.
-              To suppress this message, run 'rails rails_admin:install' to setup the asset delivery method suitable to you.
-            MSG
-            :sprockets
-          end
+        @asset_source = if defined?(Webpacker)
+          :webpacker
+        elsif Rails.root.join('webpack.config.js').exist?
+          :webpack
+        elsif Rails.root.join('config/importmap.rb').exist?
+          :importmap
+        else
+          :sprockets
+        end
       end
 
       def default_hidden_fields=(fields)

lib/rails_admin/engine.rb

@@ -10,19 +10,9 @@ module RailsAdmin
   class Engine < Rails::Engine
     isolate_namespace RailsAdmin
 
-    config.action_dispatch.rescue_responses['RailsAdmin::ActionNotAllowed'] = :forbidden
+    attr_accessor :importmap
 
-    initializer 'RailsAdmin precompile hook', group: :all do |app|
-      if app.config.respond_to?(:assets)
-        app.config.assets.precompile += %w[
-          rails_admin/application.js
-          rails_admin/application.css
-        ]
-        app.config.assets.paths << RailsAdmin::Engine.root.join('src')
-        require 'rails_admin/support/esmodule_preprocessor'
-        Sprockets.register_preprocessor 'application/javascript', RailsAdmin::ESModulePreprocessor
-      end
-    end
+    config.action_dispatch.rescue_responses['RailsAdmin::ActionNotAllowed'] = :forbidden
 
     initializer 'RailsAdmin reload config in development' do |app|
       config.initializer_path = app.root.join('config/initializers/rails_admin.rb')
@@ -44,6 +34,28 @@ class Engine < Rails::Engine
       end
     end
 
+    initializer 'RailsAdmin apply configuration', after: :eager_load! do |app|
+      RailsAdmin::Config.initialize!
+
+      # Force route reload, since it doesn't reflect RailsAdmin action configuration yet
+      app.reload_routes!
+    end
+
+    initializer 'RailsAdmin precompile hook', group: :all, after: 'RailsAdmin apply configuration' do |app|
+      case RailsAdmin.config.asset_source
+      when :sprockets
+        app.config.assets.precompile += %w[
+          rails_admin/application.js
+          rails_admin/application.css
+        ]
+        app.config.assets.paths << RailsAdmin::Engine.root.join('src')
+        require 'rails_admin/support/esmodule_preprocessor'
+        Sprockets.register_preprocessor 'application/javascript', RailsAdmin::ESModulePreprocessor
+      when :importmap
+        self.importmap = Importmap::Map.new.draw(app.root.join('config/importmap.rails_admin.rb'))
+      end
+    end
+
     # Check for required middlewares, users may forget to use them in Rails API mode
     config.after_initialize do |app|
       has_session_store = app.config.middleware.to_a.any? do |m|
@@ -66,11 +78,6 @@ class Engine < Rails::Engine
           to config/application.rb.
         ERROR
       end
-
-      RailsAdmin::Config.initialize!
-
-      # Force route reload, since it doesn't reflect RailsAdmin action configuration yet
-      app.reload_routes!
     end
   end
 end

lib/rails_admin/support/esmodule_preprocessor.rb

@@ -13,6 +13,8 @@ def self.call(input)
     def initialize; end
 
     def call(input)
+      return unless RailsAdmin.config.asset_source == :sprockets
+
       data = input[:data]
 
       if input[:filename].start_with? RailsAdmin::Engine.root.join('src').to_s

spec/dummy_app/.gitignore

@@ -7,6 +7,9 @@
 # Ignore bundler config
 /.bundle
 
+/app/assets/builds/*
+!/app/assets/builds/.keep
+
 # Ignore the default SQLite database.
 /db/*.sqlite3