get a list of gems when filling out the gemfile

3 files changed, 42 insertions, 13 deletions

diff --git a/railties/lib/rails/generators/app_base.rb b/railties/lib/rails/generators/app_base.rb
index 28a1a0b0f5..6154b2068b 100644
--- a/railties/lib/rails/generators/app_base.rb
+++ b/railties/lib/rails/generators/app_base.rb
@@ -136,22 +136,35 @@ module Rails
         options[value] ? '# ' : ''
       end
 
+      GemfileGem = Struct.new(:name, :comment, :version, :path, :github) do
+        def self.github(name, github)
+          new(name, nil, nil, nil, github)
+        end
+
+        def self.path(name, path)
+          new(name, nil, nil, path)
+        end
+
+        def padding(max_width)
+          ' ' * (max_width - name.length + 2)
+        end
+      end
+
       def rails_gemfile_entry
         if options.dev?
-          <<-GEMFILE.strip_heredoc
-            gem 'rails',     path: '#{Rails::Generators::RAILS_DEV_PATH}'
-            gem 'arel',      github: 'rails/arel'
-          GEMFILE
+          [
+            GemfileGem.path('rails', Rails::Generators::RAILS_DEV_PATH),
+            GemfileGem.github('arel', 'rails/arel'),
+          ]
         elsif options.edge?
-          <<-GEMFILE.strip_heredoc
-            gem 'rails',     github: 'rails/rails'
-            gem 'arel',      github: 'rails/arel'
-          GEMFILE
+          [
+            GemfileGem.path('rails', 'rails/rails'),
+            GemfileGem.path('arel', 'rails/arel'),
+          ]
         else
-          <<-GEMFILE.strip_heredoc
-            # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
-            gem 'rails', '#{Rails::VERSION::STRING}'
-          GEMFILE
+          [
+            GemfileGem.new('rails', "Bundle edge Rails instead: gem 'rails', github: 'rails/rails'", Rails::VERSION::STRING)
+          ]
         end
       end
 
diff --git a/railties/lib/rails/generators/rails/app/app_generator.rb b/railties/lib/rails/generators/rails/app/app_generator.rb
index 4e92f56b2d..42b9fe9a34 100644
--- a/railties/lib/rails/generators/rails/app/app_generator.rb
+++ b/railties/lib/rails/generators/rails/app/app_generator.rb
@@ -162,6 +162,10 @@ module Rails
         end
       end
 
+      def gemfile_gems
+        rails_gemfile_entry
+      end
+
       public_task :set_default_accessors!
       public_task :create_root
 
diff --git a/railties/lib/rails/generators/rails/app/templates/Gemfile b/railties/lib/rails/generators/rails/app/templates/Gemfile
index 4048930c8d..21dc915aab 100644
--- a/railties/lib/rails/generators/rails/app/templates/Gemfile
+++ b/railties/lib/rails/generators/rails/app/templates/Gemfile
@@ -1,6 +1,18 @@
 source 'https://rubygems.org'
 
-<%= rails_gemfile_entry -%>
+<% max_width = gemfile_gems.map { |g| g.name.length }.max -%>
+<% gemfile_gems.each do |gem| -%>
+<%= gem.comment -%>
+<% if gem.version -%>
+gem '<%= gem.name %>',<%= gem.padding(max_width) %>'<%= gem.version %>'
+<% elsif gem.path -%>
+gem '<%= gem.name %>',<%= gem.padding(max_width) %>path: '<%= gem.path %>'
+<% elsif gem.github -%>
+gem '<%= gem.name %>',<%= gem.padding(max_width) %>github: '<%= gem.github %>'
+<% else -%>
+gem '<%= gem.name %>'
+<% end -%>
+<% end -%>
 
 <%= database_gemfile_entry -%>