Merge branch 'master' into activestorage-guide

4 files changed, 85 insertions, 32 deletions

diff --git a/actionview/lib/action_view/helpers/asset_tag_helper.rb b/actionview/lib/action_view/helpers/asset_tag_helper.rb
index e362f13798..da630129cb 100644
--- a/actionview/lib/action_view/helpers/asset_tag_helper.rb
+++ b/actionview/lib/action_view/helpers/asset_tag_helper.rb
@@ -2,6 +2,8 @@
 
 require "active_support/core_ext/array/extract_options"
 require "active_support/core_ext/hash/keys"
+require "active_support/core_ext/object/inclusion"
+require "active_support/core_ext/object/try"
 require "action_view/helpers/asset_url_helper"
 require "action_view/helpers/tag_helper"
 
@@ -91,7 +93,7 @@ module ActionView
           content_tag("script".freeze, "", tag_options)
         }.join("\n").html_safe
 
-        request.send_early_hints("Link" => early_hints_links.join("\n")) if respond_to?(:request)
+        request.send_early_hints("Link" => early_hints_links.join("\n")) if respond_to?(:request) && request
 
         sources_tags
       end
@@ -140,7 +142,7 @@ module ActionView
           tag(:link, tag_options)
         }.join("\n").html_safe
 
-        request.send_early_hints("Link" => early_hints_links.join("\n")) if respond_to?(:request)
+        request.send_early_hints("Link" => early_hints_links.join("\n")) if respond_to?(:request) && request
 
         sources_tags
       end
@@ -221,6 +223,67 @@ module ActionView
         }.merge!(options.symbolize_keys))
       end
 
+      # Returns a link tag that browsers can use to preload the +source+.
+      # The +source+ can be the path of an resource managed by asset pipeline,
+      # a full path or an URI.
+      #
+      # ==== Options
+      #
+      # * <tt>:type</tt>  - Override the auto-generated mime type, defaults to the mime type for +source+ extension.
+      # * <tt>:as</tt>  - Override the auto-generated value for as attribute, calculated using +source+ extension and mime type.
+      # * <tt>:crossorigin</tt>  - Specify the crossorigin attribute, required to load cross-origin resources.
+      # * <tt>:nopush</tt>  - Specify if the use of server push is not desired for the resource. Defaults to +false+.
+      #
+      # ==== Examples
+      #
+      #   preload_link_tag("custom_theme.css")
+      #   # => <link rel="preload" href="/assets/custom_theme.css" as="style" type="text/css" />
+      #
+      #   preload_link_tag("/videos/video.webm")
+      #   # => <link rel="preload" href="/videos/video.mp4" as="video" type="video/webm" />
+      #
+      #   preload_link_tag(post_path(format: :json), as: "fetch")
+      #   # => <link rel="preload" href="/posts.json" as="fetch" type="application/json" />
+      #
+      #   preload_link_tag("worker.js", as: "worker")
+      #   # => <link rel="preload" href="/assets/worker.js" as="worker" type="text/javascript" />
+      #
+      #   preload_link_tag("//example.com/font.woff2")
+      #   # => <link rel="preload" href="//example.com/font.woff2" as="font" type="font/woff2" crossorigin="anonymous"/>
+      #
+      #   preload_link_tag("//example.com/font.woff2", crossorigin: "use-credentials")
+      #   # => <link rel="preload" href="//example.com/font.woff2" as="font" type="font/woff2" crossorigin="use-credentials" />
+      #
+      #   preload_link_tag("/media/audio.ogg", nopush: true)
+      #   # => <link rel="preload" href="/media/audio.ogg" as="audio" type="audio/ogg" />
+      #
+      def preload_link_tag(source, options = {})
+        href = asset_path(source, skip_pipeline: options.delete(:skip_pipeline))
+        extname = File.extname(source).downcase.delete(".")
+        mime_type = options.delete(:type) || Template::Types[extname].try(:to_s)
+        as_type = options.delete(:as) || resolve_link_as(extname, mime_type)
+        crossorigin = options.delete(:crossorigin)
+        crossorigin = "anonymous" if crossorigin == true || (crossorigin.blank? && as_type == "font")
+        nopush = options.delete(:nopush) || false
+
+        link_tag = tag.link({
+          rel: "preload",
+          href: href,
+          as: as_type,
+          type: mime_type,
+          crossorigin: crossorigin
+        }.merge!(options.symbolize_keys))
+
+        early_hints_link = "<#{href}>; rel=preload; as=#{as_type}"
+        early_hints_link += "; type=#{mime_type}" if mime_type
+        early_hints_link += "; crossorigin=#{crossorigin}" if crossorigin
+        early_hints_link += "; nopush" if nopush
+
+        request.send_early_hints("Link" => early_hints_link) if respond_to?(:request) && request
+
+        link_tag
+      end
+
       # Returns an HTML image tag for the +source+. The +source+ can be a full
       # path, a file or an Active Storage attachment.
       #
@@ -417,6 +480,18 @@ module ActionView
             raise ArgumentError, "Cannot pass a :size option with a :height or :width option"
           end
         end
+
+        def resolve_link_as(extname, mime_type)
+          if extname == "js"
+            "script"
+          elsif extname == "css"
+            "style"
+          elsif extname == "vtt"
+            "track"
+          elsif (type = mime_type.to_s.split("/")[0]) && type.in?(%w(audio video font))
+            type
+          end
+        end
     end
   end
 end
diff --git a/actionview/lib/action_view/helpers/form_helper.rb b/actionview/lib/action_view/helpers/form_helper.rb
index 6d2ace8cf8..6185aa133f 100644
--- a/actionview/lib/action_view/helpers/form_helper.rb
+++ b/actionview/lib/action_view/helpers/form_helper.rb
@@ -478,6 +478,8 @@ module ActionView
 
       mattr_accessor :form_with_generates_remote_forms, default: true
 
+      mattr_accessor :form_with_generates_ids, default: false
+
       # Creates a form tag based on mixing URLs, scopes, or models.
       #
       #   # Using just a URL:
@@ -640,16 +642,6 @@ module ActionView
       #
       # Where <tt>@document = Document.find(params[:id])</tt>.
       #
-      # When using labels +form_with+ requires setting the id on the field being
-      # labelled:
-      #
-      #   <%= form_with(model: @post) do |form| %>
-      #     <%= form.label :title %>
-      #     <%= form.text_field :title, id: :post_title %>
-      #   <% end %>
-      #
-      # See +label+ for more on how the +for+ attribute is derived.
-      #
       # === Mixing with other form helpers
       #
       # While +form_with+ uses a FormBuilder object it's possible to mix and
@@ -746,7 +738,7 @@ module ActionView
       #   end
       def form_with(model: nil, scope: nil, url: nil, format: nil, **options)
         options[:allow_method_names_outside_object] = true
-        options[:skip_default_ids] = true
+        options[:skip_default_ids] = !form_with_generates_ids
 
         if model
           url ||= polymorphic_path(model, format: format)
@@ -1044,16 +1036,6 @@ module ActionView
       # or model is yielded, so any generated field names are prefixed with
       # either the passed scope or the scope inferred from the <tt>:model</tt>.
       #
-      # When using labels +fields+ requires setting the id on the field being
-      # labelled:
-      #
-      #   <%= fields :comment do |fields| %>
-      #     <%= fields.label :body %>
-      #     <%= fields.text_field :body, id: :comment_body %>
-      #   <% end %>
-      #
-      # See +label+ for more on how the +for+ attribute is derived.
-      #
       # === Mixing with other form helpers
       #
       # While +form_with+ uses a FormBuilder object it's possible to mix and
@@ -1072,7 +1054,7 @@ module ActionView
       # FormOptionsHelper#collection_select and DateHelper#datetime_select.
       def fields(scope = nil, model: nil, **options, &block)
         options[:allow_method_names_outside_object] = true
-        options[:skip_default_ids] = true
+        options[:skip_default_ids] = !form_with_generates_ids
 
         if model
           scope ||= model_name_from_record_or_class(model).param_key
@@ -1985,7 +1967,7 @@ module ActionView
       # See the docs for the <tt>ActionView::FormHelper.fields</tt> helper method.
       def fields(scope = nil, model: nil, **options, &block)
         options[:allow_method_names_outside_object] = true
-        options[:skip_default_ids] = true
+        options[:skip_default_ids] = !FormHelper.form_with_generates_ids
 
         convert_to_legacy_options(options)
 
diff --git a/actionview/lib/action_view/helpers/tags/base.rb b/actionview/lib/action_view/helpers/tags/base.rb
index 8934a9894c..fed908fcdb 100644
--- a/actionview/lib/action_view/helpers/tags/base.rb
+++ b/actionview/lib/action_view/helpers/tags/base.rb
@@ -97,7 +97,7 @@ module ActionView
             index = name_and_id_index(options)
             options["name"] = options.fetch("name") { tag_name(options["multiple"], index) }
 
-            unless skip_default_ids?
+            if generate_ids?
               options["id"] = options.fetch("id") { tag_id(index) }
               if namespace = options.delete("namespace")
                 options["id"] = options["id"] ? "#{namespace}_#{options['id']}" : namespace
@@ -183,8 +183,8 @@ module ActionView
             end
           end
 
-          def skip_default_ids?
-            @skip_default_ids
+          def generate_ids?
+            !@skip_default_ids
           end
       end
     end
diff --git a/actionview/lib/action_view/helpers/tags/label.rb b/actionview/lib/action_view/helpers/tags/label.rb
index 56b48bbd62..02bd099784 100644
--- a/actionview/lib/action_view/helpers/tags/label.rb
+++ b/actionview/lib/action_view/helpers/tags/label.rb
@@ -75,10 +75,6 @@ module ActionView
           def render_component(builder)
             builder.translation
           end
-
-          def skip_default_ids?
-            false # The id is used as the `for` attribute.
-          end
       end
     end
   end