component.rb in actionview-component-1.0.0

- old
+ new
@@ -1,23 +1,132 @@
-module ActionView
-  class Component < Base
+# frozen_string_literal: true
+
+# Monkey patch ActionView::Base#render to support ActionView::Component
+#
+# Upstreamed in https://github.com/rails/rails/pull/36388
+# Necessary for Rails versions < 6.1.0.alpha
+class ActionView::Base
+  module RenderMonkeyPatch
+    def render(component, _ = nil, &block)
+      return super unless component.respond_to?(:render_in)
+
+      component.render_in(self, &block)
+    end
   end
 
-  class TemplateRenderer
-    module ComponentTemplates
-      def render(context, options)
-        if options.key?(:component)
-          name    = options[:component]
-          klass   = "#{name}_component".classify.constantize
-          args    = options.except(:component)
-          context = args.empty? ? klass.new : klass.new(args)
+  prepend RenderMonkeyPatch unless Rails::VERSION::MINOR > 0 && Rails::VERSION::MAJOR == 6
+end
 
-          super context, template: "components/#{name}"
+module ActionView
+  class Component < ActionView::Base
+    VERSION = "1.0.0"
+
+    include ActiveModel::Validations
+
+    # Entrypoint for rendering components. Called by ActionView::Base#render.
+    #
+    # view_context: ActionView context from calling view
+    # args(hash): params to be passed to component being rendered
+    # block: optional block to be captured within the view context
+    #
+    # returns HTML that has been escaped by the respective template handler
+    #
+    # Example subclass:
+    #
+    # app/components/my_component.rb:
+    # class MyComponent < ActionView::Component
+    #   def initialize(title:)
+    #     @title = title
+    #   end
+    # end
+    #
+    # app/components/my_component.html.erb
+    # <span title="<%= @title %>">Hello, <%= content %>!</span>
+    #
+    # In use:
+    # <%= render MyComponent.new(title: "greeting") do %>world<% end %>
+    # returns:
+    # <span title="greeting">Hello, world!</span>
+    #
+    def render_in(view_context, *args, &block)
+      self.class.compile
+      @content = view_context.capture(&block) if block_given?
+      validate!
+      call
+    end
+
+    def initialize(*); end
+
+    class << self
+      def inherited(child)
+        child.include Rails.application.routes.url_helpers unless child < Rails.application.routes.url_helpers
+
+        super
+      end
+
+      # Compile template to #call instance method, assuming it hasn't been compiled already.
+      # We could in theory do this on app boot, at least in production environments.
+      # Right now this just compiles the template the first time the component is rendered.
+      def compile
+        return if @compiled
+
+        class_eval("def call; @output_buffer = ActionView::OutputBuffer.new; #{compiled_template}; end")
+
+        @compiled = true
+      end
+
+      private
+
+      def compiled_template
+        handler = ActionView::Template.handler_for_extension(File.extname(template_file_path).gsub(".", ""))
+        template = File.read(template_file_path)
+
+        if handler.method(:call).parameters.length > 1
+          handler.call(DummyTemplate.new, template)
         else
-          super
+          handler.call(DummyTemplate.new(template))
         end
       end
+
+      def template_file_path
+        raise NotImplementedError.new("#{self} must implement #initialize.") unless self.instance_method(:initialize).owner == self
+
+        filename = self.instance_method(:initialize).source_location[0]
+        filename_without_extension = filename[0..-(File.extname(filename).length + 1)]
+        sibling_files = Dir["#{filename_without_extension}.*"] - [filename]
+
+        if sibling_files.length > 1
+          raise StandardError.new("More than one template found for #{self}. There can only be one sidecar template file per component.")
+        end
+
+        if sibling_files.length == 0
+          raise NotImplementedError.new(
+            "Could not find a template for #{self}. Either define a .template method or add a sidecar template file."
+          )
+        end
+
+        sibling_files[0]
+      end
     end
 
-    prepend ComponentTemplates
+    class DummyTemplate
+      attr_reader :source
+
+      def initialize(source = nil)
+        @source = source
+      end
+
+      def identifier
+        ""
+      end
+
+      # we'll eventually want to update this to support other types
+      def type
+        "text/html"
+      end
+    end
+
+    private
+
+    attr_reader :content
   end
 end