auto register server components and immediately hydrate stores

lib/react_on_rails/configuration.rb

@@ -9,6 +9,7 @@ def self.configure
   end
 
   DEFAULT_GENERATED_ASSETS_DIR = File.join(%w[public webpack], Rails.env).freeze
+  DEFAULT_RSC_RENDERING_URL = "rsc/".freeze
 
   def self.configuration
     @configuration ||= Configuration.new(
@@ -42,7 +43,9 @@ def self.configuration
       make_generated_server_bundle_the_entrypoint: false,
       defer_generated_component_packs: true,
       # forces the loading of React components
-      force_load: false
+      force_load: false,
+      auto_load_server_components: true,
+      rsc_rendering_url: DEFAULT_RSC_RENDERING_URL
     )
   end
 
@@ -57,7 +60,7 @@ class Configuration
                   :same_bundle_for_client_and_server, :rendering_props_extension,
                   :make_generated_server_bundle_the_entrypoint,
                   :defer_generated_component_packs, :rsc_bundle_js_file,
-                  :force_load
+                  :force_load, :auto_load_server_components, :rsc_rendering_url
 
     # rubocop:disable Metrics/AbcSize
     def initialize(node_modules_location: nil, server_bundle_js_file: nil, prerender: nil,
@@ -73,7 +76,7 @@ def initialize(node_modules_location: nil, server_bundle_js_file: nil, prerender
                    i18n_dir: nil, i18n_yml_dir: nil, i18n_output_format: nil,
                    random_dom_id: nil, server_render_method: nil, rendering_props_extension: nil,
                    components_subdirectory: nil, auto_load_bundle: nil, force_load: nil,
-                   rsc_bundle_js_file: nil)
+                   rsc_bundle_js_file: nil, auto_load_server_components: nil, rsc_rendering_url: nil)
       self.node_modules_location = node_modules_location.present? ? node_modules_location : Rails.root
       self.generated_assets_dirs = generated_assets_dirs
       self.generated_assets_dir = generated_assets_dir
@@ -113,6 +116,8 @@ def initialize(node_modules_location: nil, server_bundle_js_file: nil, prerender
       self.make_generated_server_bundle_the_entrypoint = make_generated_server_bundle_the_entrypoint
       self.defer_generated_component_packs = defer_generated_component_packs
       self.force_load = force_load
+      self.auto_load_server_components = auto_load_server_components
+      self.rsc_rendering_url = rsc_rendering_url
     end
     # rubocop:enable Metrics/AbcSize
 

lib/react_on_rails/helper.rb

@@ -17,6 +17,8 @@ module Helper
     include ReactOnRails::Utils::Required
 
     COMPONENT_HTML_KEY = "componentHtml"
+    ADD_COMPONENT_TO_PENDING_HYDRATION_FUNCTION = "$ROR_PC"
+    ADD_STORE_TO_PENDING_HYDRATION_FUNCTION = "$ROR_PS"
 
     # react_component_name: can be a React function or class component or a "Render-Function".
     # "Render-Functions" differ from a React function in that they take two parameters, the
@@ -400,6 +402,17 @@ def run_stream_inside_fiber
       rendering_fiber.resume
     end
 
+    def registered_stores
+      (@registered_stores || []) + (@registered_stores_defer_render || [])
+    end
+
+    def create_render_options(react_component_name, options)
+      # If no store dependencies are passed, default to all registered stores up till now
+      options[:store_dependencies] ||= registered_stores.map { |store| store[:store_name] }
+      ReactOnRails::ReactComponent::RenderOptions.new(react_component_name: react_component_name,
+                                                      options: options)
+    end
+
     def internal_stream_react_component(component_name, options = {})
       options = options.merge(stream?: true)
       result = internal_react_component(component_name, options)
@@ -511,12 +524,8 @@ def build_react_component_result_for_server_rendered_hash(
     end
 
     def compose_react_component_html_with_spec_and_console(component_specification_tag, rendered_output, console_script, dom_id = nil)
-      hydrate_script = dom_id.present? ? content_tag(:script, %(
-window.REACT_ON_RAILS_PENDING_COMPONENT_DOM_IDS.push('#{dom_id}');
-if (window.ReactOnRails) {
-  window.ReactOnRails.renderOrHydrateLoadedComponents();
-}
-      ).html_safe) : ""
+      add_component_to_pending_hydration_code = "window.#{ADD_COMPONENT_TO_PENDING_HYDRATION_FUNCTION}('#{dom_id}');"
+      hydrate_script = dom_id.present? ? content_tag(:script, add_component_to_pending_hydration_code.html_safe) : ""
       # IMPORTANT: Ensure that we mark string as html_safe to avoid escaping.
       html_content = <<~HTML
         #{rendered_output}
@@ -538,11 +547,26 @@ def rails_context_if_not_already_rendered
                                       json_safe_and_pretty(data).html_safe,
                                       type: "application/json",
                                       id: "js-react-on-rails-context")
+
+      pending_hydration_script = <<~JS.strip_heredoc
+        window.REACT_ON_RAILS_PENDING_COMPONENT_DOM_IDS = [];
+        window.REACT_ON_RAILS_PENDING_STORE_NAMES = [];
+        window.#{ADD_COMPONENT_TO_PENDING_HYDRATION_FUNCTION} = function(domId) {
+          window.REACT_ON_RAILS_PENDING_COMPONENT_DOM_IDS.push(domId);
+          if (window.ReactOnRails) {
+            window.ReactOnRails.renderOrHydrateLoadedComponents();
+          }
+        };
+        window.#{ADD_STORE_TO_PENDING_HYDRATION_FUNCTION} = function(storeName) {
+          window.REACT_ON_RAILS_PENDING_STORE_NAMES.push(storeName);
+          if (window.ReactOnRails) {
+            window.ReactOnRails.hydratePendingStores();
+          }
+        };
+      JS
       rails_context_tag.concat(
-        content_tag(:script, %(
-window.REACT_ON_RAILS_PENDING_COMPONENT_DOM_IDS = [];
-        ).html_safe)
-      )
+        content_tag(:script, pending_hydration_script.html_safe)
+      ).html_safe
     end
 
     # prepend the rails_context if not yet applied
@@ -558,8 +582,7 @@ def internal_react_component(react_component_name, options = {})
       # (re-hydrate the data). This enables react rendered on the client to see that the
       # server has already rendered the HTML.
 
-      render_options = ReactOnRails::ReactComponent::RenderOptions.new(react_component_name: react_component_name,
-                                                                       options: options)
+      render_options = create_render_options(react_component_name, options)
 
       # Setup the page_loaded_js, which is the same regardless of prerendering or not!
       # The reason is that React is smart about not doing extra work if the server rendering did its job.
@@ -570,7 +593,9 @@ def internal_react_component(react_component_name, options = {})
                                                 id: "js-react-on-rails-component-#{render_options.dom_id}",
                                                 "data-component-name" => render_options.react_component_name,
                                                 "data-trace" => (render_options.trace ? true : nil),
-                                                "data-dom-id" => render_options.dom_id)
+                                                "data-dom-id" => render_options.dom_id,
+                                                "data-store-dependencies" => render_options.store_dependencies.to_json,
+                                                )
 
       if render_options.force_load
         component_specification_tag.concat(
@@ -592,12 +617,17 @@ def internal_react_component(react_component_name, options = {})
     end
 
     def render_redux_store_data(redux_store_data)
-      result = content_tag(:script,
+      store_hydration_data = content_tag(:script,
                            json_safe_and_pretty(redux_store_data[:props]).html_safe,
                            type: "application/json",
                            "data-js-react-on-rails-store" => redux_store_data[:store_name].html_safe)
+      hydration_code = "window.#{ADD_STORE_TO_PENDING_HYDRATION_FUNCTION}('#{redux_store_data[:store_name]}');"
+      store_hydration_script = content_tag(:script, hydration_code.html_safe)
 
-      prepend_render_rails_context(result)
+      prepend_render_rails_context <<~HTML
+        #{store_hydration_data}
+        #{store_hydration_script}
+      HTML
     end
 
     def props_string(props)
@@ -654,7 +684,7 @@ def server_rendered_react_component(render_options)
       js_code = ReactOnRails::ServerRenderingJsCode.server_rendering_component_js_code(
         props_string: props_string(props).gsub("\u2028", '\u2028').gsub("\u2029", '\u2029'),
         rails_context: rails_context(server_side: true).to_json,
-        redux_stores: initialize_redux_stores,
+        redux_stores: initialize_redux_stores(render_options),
         react_component_name: react_component_name,
         render_options: render_options
       )
@@ -688,17 +718,18 @@ def server_rendered_react_component(render_options)
       result
     end
 
-    def initialize_redux_stores
+    def initialize_redux_stores(render_options)
       result = +<<-JS
       ReactOnRails.clearHydratedStores();
       JS
 
-      return result unless @registered_stores.present? || @registered_stores_defer_render.present?
+      store_dependencies = render_options.store_dependencies
+      return result unless store_dependencies.present?
 
       declarations = +"var reduxProps, store, storeGenerator;\n"
-      all_stores = (@registered_stores || []) + (@registered_stores_defer_render || [])
+      store_objects = registered_stores.select { |store| store_dependencies.include?(store[:store_name]) }
 
-      result << all_stores.each_with_object(declarations) do |redux_store_data, memo|
+      result << store_objects.each_with_object(declarations) do |redux_store_data, memo|
         store_name = redux_store_data[:store_name]
         props = props_string(redux_store_data[:props])
         memo << <<-JS.strip_heredoc

lib/react_on_rails/packs_generator.rb

@@ -44,13 +44,60 @@ def create_pack(file_path)
       puts(Rainbow("Generated Packs: #{output_path}").yellow)
     end
 
+    def first_js_statement_in_code(content)
+      return "" if content.nil? || content.empty?
+
+      start_index = 0
+      content_length = content.length
+
+      while start_index < content_length
+        # Skip whitespace
+        while start_index < content_length && content[start_index].match?(/\s/)
+          start_index += 1
+        end
+
+        break if start_index >= content_length
+
+        current_chars = content[start_index, 2]
+
+        case current_chars
+        when '//'
+          # Single-line comment
+          newline_index = content.index("\n", start_index)
+          return "" if newline_index.nil?
+          start_index = newline_index + 1
+        when '/*'
+          # Multi-line comment
+          comment_end = content.index('*/', start_index)
+          return "" if comment_end.nil?
+          start_index = comment_end + 2
+        else
+          # Found actual content
+          next_line_index = content.index("\n", start_index)
+          return next_line_index ? content[start_index...next_line_index].strip : content[start_index..].strip
+        end
+      end
+
+      ""
+    end
+
+    def is_client_entrypoint?(file_path)
+      content = File.read(file_path)
+      # has "use client" directive. It can be "use client" or 'use client'
+      first_js_statement_in_code(content).match?(/^["']use client["'](?:;|\s|$)/)
+    end
+
     def pack_file_contents(file_path)
       registered_component_name = component_name(file_path)
+      register_as_server_component = ReactOnRails.configuration.auto_load_server_components && !is_client_entrypoint?(file_path)
+      import_statement = register_as_server_component ? "" : "import #{registered_component_name} from '#{relative_component_path_from_generated_pack(file_path)}';"
+      register_call = register_as_server_component ? "registerServerComponent(\"#{registered_component_name}\")" : "register({#{registered_component_name}})";
+
       <<~FILE_CONTENT
         import ReactOnRails from 'react-on-rails';
-        import #{registered_component_name} from '#{relative_component_path_from_generated_pack(file_path)}';
+        #{import_statement}
 
-        ReactOnRails.register({#{registered_component_name}});
+        ReactOnRails.#{register_call};
       FILE_CONTENT
     end
 

lib/react_on_rails/react_component/render_options.rb

@@ -119,6 +119,10 @@ def rsc?
         options[:rsc?]
       end
 
+      def store_dependencies
+        options[:store_dependencies]
+      end
+
       private
 
       attr_reader :options

node_package/src/ComponentRegistry.ts

@@ -1,4 +1,5 @@
-import type { RegisteredComponent, ReactComponentOrRenderFunction, RenderFunction } from './types/index';
+import React from 'react';
+import type { RegisteredComponent, ReactComponentOrRenderFunction, RenderFunction, ReactComponent } from './types/index';
 import isRenderFunction from './isRenderFunction';
 
 const registeredComponents = new Map<string, RegisteredComponent>();
@@ -60,6 +61,17 @@ export default {
     });
   },
 
+  registerServerComponent(...componentNames: string[]): void {
+    // eslint-disable-next-line global-require, @typescript-eslint/no-var-requires
+    const RSCClientRoot = require('./RSCClientRoot').default;
+
+    const componentsWrappedInRSCClientRoot = componentNames.reduce(
+      (acc, name) => ({ ...acc, [name]: () => React.createElement(RSCClientRoot, { componentName: name }) }),
+      {}
+    );
+    this.register(componentsWrappedInRSCClientRoot);
+  },
+
   /**
    * @param name
    * @returns { name, component, isRenderFunction, isRenderer }

node_package/src/RSCClientRoot.ts

@@ -0,0 +1,23 @@
+import * as React from 'react';
+import RSDWClient from 'react-server-dom-webpack/client';
+
+if (!('use' in React)) {
+  throw new Error('React.use is not defined. Please ensure you are using React 18.3.0-canary-670811593-20240322 or later to use server components.');
+}
+
+// It's not the exact type, but it's close enough for now
+type Use = <T>(promise: Promise<T>) => T;
+const { use } = React as { use: Use };
+
+const renderCache: Record<string, Promise<unknown>> = {};
+
+const fetchRSC = ({ componentName }: { componentName: string }) => {
+  if (!renderCache[componentName]) {
+    renderCache[componentName] = RSDWClient.createFromFetch(fetch(`/rsc/${componentName}`));
+  }
+  return renderCache[componentName];
+}
+
+const RSCClientRoot = ({ componentName }: { componentName: string }) => use(fetchRSC({ componentName }));
+
+export default RSCClientRoot;

node_package/src/ReactOnRails.ts

@@ -55,6 +55,16 @@ ctx.ReactOnRails = {
     ComponentRegistry.register(components);
   },
 
+  /**
+   * Register a specific component as a server component.
+   * The component will not be included in the client bundle.
+   * When it's rendered, a call will be made to the server to render it.
+   * @param componentNames
+   */
+  registerServerComponent(...componentNames: string[]): void {
+    ComponentRegistry.registerServerComponent(...componentNames);
+  },
+
   registerStore(stores: { [id: string]: StoreGenerator }): void {
     this.registerStoreGenerators(stores);
   },
@@ -87,6 +97,24 @@ ctx.ReactOnRails = {
     return StoreRegistry.getStore(name, throwIfMissing);
   },
 
+  /**
+   * Get a store by name, or wait for it to be registered.
+   * @param name
+   * @returns Promise<Store>
+   */
+  getOrWaitForStore(name: string): Promise<Store> {
+    return StoreRegistry.getOrWaitForStore(name);
+  },
+
+  /**
+   * Get a store generator by name, or wait for it to be registered.
+   * @param name
+   * @returns Promise<StoreGenerator>
+   */
+  getOrWaitForStoreGenerator(name: string): Promise<StoreGenerator> {
+    return StoreRegistry.getOrWaitForStoreGenerator(name);
+  },
+
   /**
    * Renders or hydrates the react element passed. In case react version is >=18 will use the new api.
    * @param domNode
@@ -140,6 +168,10 @@ ctx.ReactOnRails = {
     ClientStartup.renderOrHydrateLoadedComponents();
   },
 
+  hydratePendingStores(): void {
+    ClientStartup.hydratePendingStores();
+  },
+
   reactOnRailsComponentLoaded(domId: string): void {
     ClientStartup.reactOnRailsComponentLoaded(domId);
   },