Module: ActionController::ImplicitRender

Includes:
BasicImplicitRender
Defined in:
actionpack/lib/action_controller/metal/implicit_render.rb

Overview

Handles implicit rendering for a controller action that does not explicitly respond with render, respond_to, redirect, or head.

For API controllers, the implicit response is always 204 No Content.

For all other controllers, we use these heuristics to decide whether to render a template, raise an error for a missing template, or respond with 204 No Content:

First, if we DO find a template, it's rendered. Template lookup accounts for the action name, locales, format, variant, template handlers, and more (see render for details).

Second, if we DON'T find a template but the controller action does have templates for other formats, variants, etc., then we trust that you meant to provide a template for this response, too, and we raise ActionController::UnknownFormat with an explanation.

Third, if we DON'T find a template AND the request is a page load in a web browser (technically, a non-XHR GET request for an HTML response) where you reasonably expect to have rendered a template, then we raise ActionView::UnknownFormat with an explanation.

Finally, if we DON'T find a template AND the request isn't a browser page load, then we implicitly respond with 204 No Content.

Instance Method Summary collapse

Methods included from BasicImplicitRender

#send_action

Instance Method Details

#default_render(*args) ⇒ Object


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# File 'actionpack/lib/action_controller/metal/implicit_render.rb', line 34

def default_render(*args)
  if template_exists?(action_name.to_s, _prefixes, variants: request.variant)
    render(*args)
  elsif any_templates?(action_name.to_s, _prefixes)
    message = "#{self.class.name}\##{action_name} is missing a template " \
      "for this request format and variant.\n" \
      "\nrequest.formats: #{request.formats.map(&:to_s).inspect}" \
      "\nrequest.variant: #{request.variant.inspect}"

    raise ActionController::UnknownFormat, message
  elsif interactive_browser_request?
    message = "#{self.class.name}\##{action_name} is missing a template " \
      "for this request format and variant.\n\n" \
      "request.formats: #{request.formats.map(&:to_s).inspect}\n" \
      "request.variant: #{request.variant.inspect}\n\n" \
      "NOTE! For XHR/Ajax or API requests, this action would normally " \
      "respond with 204 No Content: an empty white screen. Since you're " \
      "loading it in a web browser, we assume that you expected to " \
      "actually render a template, not nothing, so we're showing an " \
      "error to be extra-clear. If you expect 204 No Content, carry on. " \
      "That's what you'll get from an XHR or API request. Give it a shot."

    raise ActionController::UnknownFormat, message
  else
    logger.info "No template found for #{self.class.name}\##{action_name}, rendering head :no_content" if logger
    super
  end
end

#method_for_action(action_name) ⇒ Object


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# File 'actionpack/lib/action_controller/metal/implicit_render.rb', line 63

def method_for_action(action_name)
  super || if template_exists?(action_name.to_s, _prefixes)
    "default_render"
  end
end