daad7144ec
This refactors the Markdown pipeline so it supports the rendering of multiple documents that may belong to different projects. An example of where this happens is when displaying the event feed of a group. In this case we retrieve events for all projects in the group. Previously we would group events per project and render these chunks separately, but this would result in many SQL queries being executed. By extending the Markdown pipeline to support this out of the box we can drastically reduce the number of SQL queries. To achieve this we introduce a new object to the pipeline: Banzai::RenderContext. This object simply wraps two other objects: an optional Project instance, and an optional User instance. On its own this wouldn't be very helpful, but a RenderContext can also be used to associate HTML documents with specific Project instances. This work is done in Banzai::ObjectRenderer and allows us to reuse as many queries (and results) as possible.
97 lines
3.4 KiB
Ruby
97 lines
3.4 KiB
Ruby
module Banzai
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# Class for rendering multiple objects (e.g. Note instances) in a single pass,
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# using +render_field+ to benefit from caching in the database. Rendering and
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# redaction are both performed.
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#
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# The unredacted HTML is generated according to the usual +render_field+
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# policy, so specify the pipeline and any other context options on the model.
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#
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# The *redacted* (i.e., suitable for use) HTML is placed in an attribute
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# named "redacted_<foo>", where <foo> is the name of the cache field for the
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# chosen attribute.
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#
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# As an example, rendering the attribute `note` would place the unredacted
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# HTML into `note_html` and the redacted HTML into `redacted_note_html`.
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class ObjectRenderer
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attr_reader :context
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# default_project - A default Project to use for redacting Markdown.
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# user - The user viewing the Markdown/HTML documents, if any.
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# redaction_context - A Hash containing extra attributes to use during redaction
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def initialize(default_project: nil, user: nil, redaction_context: {})
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@context = RenderContext.new(default_project, user)
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@redaction_context = base_context.merge(redaction_context)
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end
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# Renders and redacts an Array of objects.
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#
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# objects - The objects to render.
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# attribute - The attribute containing the raw Markdown to render.
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#
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# Returns the same input objects.
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def render(objects, attribute)
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documents = render_documents(objects, attribute)
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documents = post_process_documents(documents, objects, attribute)
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redacted = redact_documents(documents)
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objects.each_with_index do |object, index|
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redacted_data = redacted[index]
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object.__send__("redacted_#{attribute}_html=", redacted_data[:document].to_html(save_options).html_safe) # rubocop:disable GitlabSecurity/PublicSend
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object.user_visible_reference_count = redacted_data[:visible_reference_count] if object.respond_to?(:user_visible_reference_count)
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end
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end
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private
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def render_documents(objects, attribute)
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pipeline = HTML::Pipeline.new([])
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objects.map do |object|
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document = pipeline.to_document(Banzai.render_field(object, attribute))
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context.associate_document(document, object)
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document
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end
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end
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def post_process_documents(documents, objects, attribute)
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# Called here to populate cache, refer to IssuableExtractor docs
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IssuableExtractor.new(context).extract(documents)
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documents.zip(objects).map do |document, object|
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pipeline_context = context_for(document, object, attribute)
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Banzai::Pipeline[:post_process].to_document(document, pipeline_context)
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end
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end
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# Redacts the list of documents.
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#
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# Returns an Array containing the redacted documents.
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def redact_documents(documents)
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redactor = Redactor.new(context)
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redactor.redact(documents)
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end
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# Returns a Banzai context for the given object and attribute.
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def context_for(document, object, attribute)
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@redaction_context.merge(object.banzai_render_context(attribute)).merge(
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project: context.project_for_node(document)
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)
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end
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def base_context
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{
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current_user: context.current_user,
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skip_redaction: true
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}
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end
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def save_options
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return {} unless @redaction_context[:xhtml]
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{ save_with: Nokogiri::XML::Node::SaveOptions::AS_XHTML }
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end
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end
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end
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