feat(inline): allow components to be rendered without a template file

CHANGELOG.md

@@ -1,5 +1,9 @@
 # master
 
+# v1.16.0
+
+* Allow components to be rendered without a template file (aka inline component).
+
 # v1.15.0
 
 * Re-introduce ActionView::Component::TestHelpers.

README.md

@@ -197,6 +197,24 @@ Which returns:
 </div>
 ```
 
+### Inline Component
+
+A component can be rendered without any template file as well.
+
+`app/components/inline_component.rb`:
+
+```ruby
+class InlineComponent < ViewComponent::Base
+  def call
+    if active?
+      link_to "Cancel integration", integration_path, method: :delete
+    else
+      link_to "Integrate now!", integration_path
+    end
+  end
+end
+```
+
 ### Conditional Rendering
 
 Components can implement a `#render?` method to determine if they should be rendered.

lib/view_component/base.rb

@@ -159,6 +159,10 @@ def compiled?
         @compiled && ActionView::Base.cache_template_loading
       end
 
+      def inlined?
+        instance_methods(false).grep(/^call/).present? && templates.empty?
+      end
+
       def compile!
         compile(raise_template_errors: true)
       end
@@ -167,7 +171,7 @@ def compile!
       # We could in theory do this on app boot, at least in production environments.
       # Right now this just compiles the first time the component is rendered.
       def compile(raise_template_errors: false)
-        return if compiled?
+        return if compiled? || inlined?
 
         if template_errors.present?
           raise ViewComponent::TemplateError.new(template_errors) if raise_template_errors

test/app/components/inline_component.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+class InlineComponent < ViewComponent::Base
+  def initialize(*); end
+
+  def call
+    text_field_tag :name
+  end
+end

test/view_component/view_component_test.rb

@@ -17,6 +17,14 @@ def test_renders_content_from_block
     assert_selector("span", text: "content")
   end
 
+  def test_render_without_template
+    render_inline(InlineComponent.new)
+
+    assert_predicate InlineComponent, :inlined?
+    assert_not_predicate InlineComponent, :compiled?
+    assert_selector("input[type='text'][name='name']")
+  end
+
   def test_renders_slim_template
     render_inline(SlimComponent.new(message: "bar")) { "foo" }