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-rw-r--r--actionpack/lib/action_controller/metal/implicit_render.rb87
1 files changed, 34 insertions, 53 deletions
diff --git a/actionpack/lib/action_controller/metal/implicit_render.rb b/actionpack/lib/action_controller/metal/implicit_render.rb
index 3a6f784507..6192fc0f9c 100644
--- a/actionpack/lib/action_controller/metal/implicit_render.rb
+++ b/actionpack/lib/action_controller/metal/implicit_render.rb
@@ -1,33 +1,31 @@
require 'active_support/core_ext/string/strip'
module ActionController
- # Handles implicit rendering for a controller action when it did not
- # explicitly indicate an appropiate response via methods such as +render+,
- # +respond_to+, +redirect+ or +head+.
+ # Handles implicit rendering for a controller action that does not
+ # explicitly respond with +render+, +respond_to+, +redirect+, or +head+.
#
- # For API controllers, the implicit render always renders "204 No Content"
- # and does not account for any templates.
+ # For API controllers, the implicit response is always 204 No Content.
#
- # For other controllers, the following conditions are checked:
+ # 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 a template exists for the controller action, it is rendered.
- # This template lookup takes into account the action name, locales, format,
- # variant, template handlers, etc. (see +render+ for details).
+ # 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 other templates exist for the controller action but is not in
- # the right format (or variant, etc.), an <tt>ActionController::UnknownFormat</tt>
- # is raised. The list of available templates is assumed to be a complete
- # enumeration of all the possible formats (or variants, etc.); that is,
- # having only HTML and JSON templates indicate that the controller action is
- # not meant to handle XML requests.
+ # 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
+ # <tt>ActionController::UnknownFormat</tt> with an explanation.
#
- # Third, if the current request is an "interactive" browser request (the user
- # navigated here by entering the URL in the address bar, submiting a form,
- # clicking on a link, etc. as opposed to an XHR or non-browser API request),
- # <tt>ActionView::UnknownFormat</tt> is raised to display a helpful error
- # message.
+ # 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
+ # <tt>ActionView::UnknownFormat</tt> with an explanation.
#
- # Finally, it falls back to the same "204 No Content" behavior as API controllers.
+ # 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.
module ImplicitRender
# :stopdoc:
@@ -37,39 +35,23 @@ module ActionController
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} does not know how to respond " \
- "to this request. There are other templates available for this controller " \
- "action but none of them were suitable for this request.\n\n" \
- "This usually happens when the client requested an unsupported format " \
- "(e.g. requesting HTML content from a JSON endpoint or vice versa), but " \
- "it might also be failing due to other constraints, such as locales or " \
- "variants.\n"
-
- if request.formats.any?
- message << "\nRequested format(s): #{request.formats.join(", ")}"
- end
-
- if request.variant.any?
- message << "\nRequested variant(s): #{request.variant.join(", ")}"
- end
+ 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 = "You did not define any templates for #{self.class.name}\##{action_name}. " \
- "This is not necessarily a problem (e.g. you might be building an API endpoint " \
- "that does not require any templates), and the controller would usually respond " \
- "with `head :no_content` for your convenience.\n\n" \
- "However, you appear to have navigated here from an interactive browser request – " \
- "such as by navigating to this URL directly, clicking on a link or submitting a form. " \
- "Rendering a `head :no_content` in this case could have resulted in unexpected UI " \
- "behavior in the browser.\n\n" \
- "If you expected the `head :no_content` response, you do not need to take any " \
- "actions – requests coming from an XHR (AJAX) request or other non-browser clients " \
- "will receive the \"204 No Content\" response as expected.\n\n" \
- "If you did not expect this behavior, you can resolve this error by adding a " \
- "template for this controller action (usually `#{action_name}.html.erb`) or " \
- "otherwise indicate the appropriate response in the action using `render`, " \
- "`redirect_to`, `head`, etc.\n"
+ 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
@@ -85,9 +67,8 @@ module ActionController
end
private
-
def interactive_browser_request?
- request.format == Mime[:html] && !request.xhr?
+ request.get? && request.format == Mime[:html] && !request.xhr?
end
end
end