ViewComponent is a Ruby library designed for crafting reusable components, akin to React. It equips developers with all the necessary tools to construct encapsulated HTML chunks that are not only easily testable but also significantly faster than the built-in partials.

Components can be rendered using render helper that is available in controllers, helpers or templates:

render MyComponent.new(name: 'Lucas') do
  <p>Hello, I am Lucas</p>
end

However, if we attempt to render the same component within a custom form builder, an error will be raised:

class MyFormBuilders < ActionView::Helpers::FormBuilder
  def submit(value = nil, options = {})
    render ButtonComponent.new(variant: :primary, size: :lg) do
      value
    end
  end
end

# undefined method `render' for an instance of MyFormBuilders

To work around this issue, helper needs to instantiate view context so that we can call the render function on it:

class MyFormBuilders < ActionView::Helpers::FormBuilder
  def submit(value = nil, options = {})
    view_context.render ButtonComponent.new(variant: :primary, size: :lg) do
      value
    end
  end

  private

  def view_context
    @view_context ||= ApplicationController.new.view_context
  end
end

Now, we can employ our view components within form builder methods, such as using a button component for form submissions.