Merge pull request #48553 from ghiculescu/preload_links_header-invoca…

…tion

Allow opting in/out of `Link preload` headers when calling `stylesheet_link_tag` or `javascript_include_tag`

actionview/CHANGELOG.md

@@ -1,3 +1,15 @@
+*   Allow opting in/out of `Link preload` headers when calling `stylesheet_link_tag` or `javascript_include_tag`
+
+    ```ruby
+    # will exclude header, even if setting is enabled:
+    javascript_include_tag("http://example.com/all.js", preload_links_header: false)
+
+    # will include header, even if setting is disabled:
+    stylesheet_link_tag("http://example.com/all.js", preload_links_header: true)
+    ```
+
+    *Alex Ghiculescu*
+
 *   Stop generating `Link preload` headers once it has reached 1KB.
 
     Some proxies have trouble handling large headers, but more importantly preload links

actionview/lib/action_view/helpers/asset_tag_helper.rb

@@ -112,6 +112,7 @@ def javascript_include_tag(*sources)
         options = sources.extract_options!.stringify_keys
         path_options = options.extract!("protocol", "extname", "host", "skip_pipeline").symbolize_keys
         preload_links = []
+        use_preload_links_header = options["preload_links_header"].nil? ? preload_links_header : options.delete("preload_links_header")
         nopush = options["nopush"].nil? ? true : options.delete("nopush")
         crossorigin = options.delete("crossorigin")
         crossorigin = "anonymous" if crossorigin == true
@@ -120,7 +121,7 @@ def javascript_include_tag(*sources)
 
         sources_tags = sources.uniq.map { |source|
           href = path_to_javascript(source, path_options)
-          if preload_links_header && !options["defer"] && href.present? && !href.start_with?("data:")
+          if use_preload_links_header && !options["defer"] && href.present? && !href.start_with?("data:")
             preload_link = "<#{href}>; rel=#{rel}; as=script"
             preload_link += "; crossorigin=#{crossorigin}" unless crossorigin.nil?
             preload_link += "; integrity=#{integrity}" unless integrity.nil?
@@ -137,7 +138,7 @@ def javascript_include_tag(*sources)
           content_tag("script", "", tag_options)
         }.join("\n").html_safe
 
-        if preload_links_header
+        if use_preload_links_header
           send_preload_links_header(preload_links)
         end
 
@@ -192,6 +193,7 @@ def javascript_include_tag(*sources)
       def stylesheet_link_tag(*sources)
         options = sources.extract_options!.stringify_keys
         path_options = options.extract!("protocol", "extname", "host", "skip_pipeline").symbolize_keys
+        use_preload_links_header = options["preload_links_header"].nil? ? preload_links_header : options.delete("preload_links_header")
         preload_links = []
         crossorigin = options.delete("crossorigin")
         crossorigin = "anonymous" if crossorigin == true
@@ -200,7 +202,7 @@ def stylesheet_link_tag(*sources)
 
         sources_tags = sources.uniq.map { |source|
           href = path_to_stylesheet(source, path_options)
-          if preload_links_header && href.present? && !href.start_with?("data:")
+          if use_preload_links_header && href.present? && !href.start_with?("data:")
             preload_link = "<#{href}>; rel=preload; as=style"
             preload_link += "; crossorigin=#{crossorigin}" unless crossorigin.nil?
             preload_link += "; integrity=#{integrity}" unless integrity.nil?
@@ -220,7 +222,7 @@ def stylesheet_link_tag(*sources)
           tag(:link, tag_options)
         }.join("\n").html_safe
 
-        if preload_links_header
+        if use_preload_links_header
           send_preload_links_header(preload_links)
         end
 

actionview/test/template/asset_tag_helper_test.rb

@@ -642,6 +642,23 @@ def test_should_not_set_preload_links_for_data_url
     end
   end
 
+  def test_should_not_set_preload_links_if_opted_out_at_invokation
+    with_preload_links_header do
+      stylesheet_link_tag("http://example.com/style.css", preload_links_header: false)
+      javascript_include_tag("http://example.com/all.js", preload_links_header: false)
+      assert_nil @response.headers["Link"]
+    end
+  end
+
+  def test_should_set_preload_links_if_opted_in_at_invokation
+    with_preload_links_header(false) do
+      stylesheet_link_tag("http://example.com/style.css", preload_links_header: true)
+      javascript_include_tag("http://example.com/all.js", preload_links_header: true)
+      expected = "<http://example.com/style.css>; rel=preload; as=style; nopush,<http://example.com/all.js>; rel=preload; as=script; nopush"
+      assert_equal expected, @response.headers["Link"]
+    end
+  end
+
   def test_should_generate_links_under_the_max_size
     with_preload_links_header do
       100.times do |i|