gitlab-org--gitlab-foss/lib/banzai/object_renderer.rb
Yorick Peterse d470f3d195
Support for rendering/redacting multiple documents
This commit changes the way certain documents are rendered (currently
only Notes) and how documents are redacted. Previously both rendering
and redacting would run on a per document basis. The result of this was
that for every document we'd have to run countless queries just to
figure out if we could display a set of links or not.

This commit changes things around so that redacting Markdown documents
is no longer tied into the html-pipeline Gem. This in turn allows it to
redact multiple documents in a single pass, thus reducing the number of
queries needed.

In turn rendering issue/merge request notes has been adjusted to take
advantage of this new setup. Instead of rendering Markdown somewhere
deep down in a view the Markdown is rendered and redacted in the
controller (taking the current user and all that into account). This has
been done in such a way that the "markdown()" helper method can still be
used on its own.

This particular commit also paves the way for caching rendered HTML on
object level. Right now there's an accessor method Note#note_html which
is used for setting/getting the rendered HTML. Once we cache HTML on row
level we can simply change this field to be a column and call a "save"
whenever needed and we're pretty much done.
2016-06-24 11:46:39 +02:00

85 lines
2.5 KiB
Ruby

module Banzai
# Class for rendering multiple objects (e.g. Note instances) in a single pass.
#
# Rendered Markdown is stored in an attribute in every object based on the
# name of the attribute containing the Markdown. For example, when the
# attribute `note` is rendered the HTML is stored in `note_html`.
class ObjectRenderer
attr_reader :project, :user
# Make sure to set the appropriate pipeline in the `raw_context` attribute
# (e.g. `:note` for Note instances).
#
# project - A Project to use for rendering and redacting Markdown.
# user - The user viewing the Markdown/HTML documents, if any.
# context - A Hash containing extra attributes to use in the rendering
# pipeline.
def initialize(project, user = nil, raw_context = {})
@project = project
@user = user
@raw_context = raw_context
end
# Renders and redacts an Array of objects.
#
# objects - The objects to render
# attribute - The attribute containing the raw Markdown to render.
#
# Returns the same input objects.
def render(objects, attribute)
documents = render_objects(objects, attribute)
redacted = redact_documents(documents)
objects.each_with_index do |object, index|
object.__send__("#{attribute}_html=", redacted.fetch(index))
end
objects
end
# Renders the attribute of every given object.
def render_objects(objects, attribute)
objects.map do |object|
render_attribute(object, attribute)
end
end
# Redacts the list of documents.
#
# Returns an Array containing the redacted documents.
def redact_documents(documents)
redactor = Redactor.new(project, user)
redactor.redact(documents).map do |document|
document.to_html.html_safe
end
end
# Returns a Banzai context for the given object and attribute.
def context_for(object, attribute)
context = base_context.merge(cache_key: [object, attribute])
if object.respond_to?(:author)
context[:author] = object.author
end
context
end
# Renders the attribute of an object.
#
# Returns a `Nokogiri::HTML::Document`.
def render_attribute(object, attribute)
context = context_for(object, attribute)
string = object.__send__(attribute)
html = Banzai.render(string, context)
Banzai::Pipeline[:relative_link].to_document(html, context)
end
def base_context
@base_context ||= @raw_context.merge(current_user: user, project: project)
end
end
end