227 lines
7.5 KiB
Ruby
227 lines
7.5 KiB
Ruby
# The ChangesetController is the RESTful interface to Changeset objects
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class ChangesetController < ApplicationController
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require 'xml/libxml'
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require 'diff_reader'
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before_filter :authorize, :only => [:create, :update, :delete, :upload, :include]
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before_filter :check_write_availability, :only => [:create, :update, :delete, :upload, :include]
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before_filter :check_read_availability, :except => [:create, :update, :delete, :upload, :download]
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after_filter :compress_output
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# Create a changeset from XML.
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def create
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if request.put?
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cs = Changeset.from_xml(request.raw_post, true)
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if cs
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cs.user_id = @user.id
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cs.save_with_tags!
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render :text => cs.id.to_s, :content_type => "text/plain"
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else
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render :nothing => true, :status => :bad_request
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end
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else
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render :nothing => true, :status => :method_not_allowed
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end
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end
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def read
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begin
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changeset = Changeset.find(params[:id])
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render :text => changeset.to_xml.to_s, :content_type => "text/xml"
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rescue ActiveRecord::RecordNotFound
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render :nothing => true, :status => :not_found
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end
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end
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def close
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begin
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unless request.put?
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render :nothing => true, :status => :method_not_allowed
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return
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end
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changeset = Changeset.find(params[:id])
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unless @user.id == changeset.user_id
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raise OSM::APIUserChangesetMismatchError
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end
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changeset.open = false
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changeset.save!
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render :nothing => true
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rescue ActiveRecord::RecordNotFound
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render :nothing => true, :status => :not_found
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end
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end
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##
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# insert a (set of) points into a changeset bounding box. this can only
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# increase the size of the bounding box. this is a hint that clients can
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# set either before uploading a large number of changes, or changes that
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# the client (but not the server) knows will affect areas further away.
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def include
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# only allow POST requests, because although this method is
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# idempotent, there is no "document" to PUT really...
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if request.post?
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cs = Changeset.find(params[:id])
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# check user credentials - only the user who opened a changeset
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# may alter it.
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unless @user.id == changeset.user_id
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raise OSM::APIUserChangesetMismatchError
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end
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# keep an array of lons and lats
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lon = Array.new
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lat = Array.new
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# the request is in pseudo-osm format... this is kind-of an
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# abuse, maybe should change to some other format?
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doc = XML::Parser.string(request.raw_post).parse
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doc.find("//osm/node").each do |n|
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lon << n['lon'].to_f * SCALE
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lat << n['lat'].to_f * SCALE
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end
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# add the existing bounding box to the lon-lat array
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lon << cs.min_lon unless cs.min_lon.nil?
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lat << cs.min_lat unless cs.min_lat.nil?
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lon << cs.max_lon unless cs.max_lon.nil?
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lat << cs.max_lat unless cs.max_lat.nil?
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# collapse the arrays to minimum and maximum
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cs.min_lon, cs.min_lat, cs.max_lon, cs.max_lat =
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lon.min, lat.min, lon.max, lat.max
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# save the larger bounding box and return the changeset, which
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# will include the bigger bounding box.
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cs.save!
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render :text => cs.to_xml.to_s, :content_type => "text/xml"
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else
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render :nothing => true, :status => :method_not_allowed
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end
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rescue ActiveRecord::RecordNotFound
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render :nothing => true, :status => :not_found
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rescue OSM::APIError => ex
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render ex.render_opts
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end
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##
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# Upload a diff in a single transaction.
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#
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# This means that each change within the diff must succeed, i.e: that
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# each version number mentioned is still current. Otherwise the entire
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# transaction *must* be rolled back.
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#
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# Furthermore, each element in the diff can only reference the current
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# changeset.
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#
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# Returns: a diffResult document, as described in
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# http://wiki.openstreetmap.org/index.php/OSM_Protocol_Version_0.6
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def upload
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# only allow POST requests, as the upload method is most definitely
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# not idempotent, as several uploads with placeholder IDs will have
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# different side-effects.
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# see http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html#sec9.1.2
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unless request.post?
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render :nothing => true, :status => :method_not_allowed
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return
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end
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# access control - only the user who created a changeset may
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# upload to it.
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unless @user.id == changeset.user_id
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raise OSM::APIUserChangesetMismatchError
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end
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changeset = Changeset.find(params[:id])
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diff_reader = DiffReader.new(request.raw_post, changeset)
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Changeset.transaction do
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result = diff_reader.commit
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render :text => result.to_s, :content_type => "text/xml"
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end
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rescue ActiveRecord::RecordNotFound
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render :nothing => true, :status => :not_found
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rescue OSM::APIError => ex
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render ex.render_opts
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end
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##
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# download the changeset as an osmChange document.
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#
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# to make it easier to revert diffs it would be better if the osmChange
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# format were reversible, i.e: contained both old and new versions of
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# modified elements. but it doesn't at the moment...
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#
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# this method cannot order the database changes fully (i.e: timestamp and
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# version number may be too coarse) so the resulting diff may not apply
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# to a different database. however since changesets are not atomic this
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# behaviour cannot be guaranteed anyway and is the result of a design
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# choice.
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def download
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changeset = Changeset.find(params[:id])
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# get all the elements in the changeset and stick them in a big array.
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elements = [changeset.old_nodes,
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changeset.old_ways,
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changeset.old_relations].flatten
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# sort the elements by timestamp and version number, as this is the
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# almost sensible ordering available. this would be much nicer if
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# global (SVN-style) versioning were used - then that would be
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# unambiguous.
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elements.sort! do |a, b|
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if (a.timestamp == b.timestamp)
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a.version <=> b.version
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else
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a.timestamp <=> b.timestamp
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end
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end
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# create an osmChange document for the output
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result = OSM::API.new.get_xml_doc
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result.root.name = "osmChange"
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# generate an output element for each operation. note: we avoid looking
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# at the history because it is simpler - but it would be more correct to
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# check these assertions.
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elements.each do |elt|
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result.root <<
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if (elt.version == 1)
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# first version, so it must be newly-created.
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created = XML::Node.new "create"
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created << elt.to_xml_node
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else
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# get the previous version from the element history
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prev_elt = elt.class.find(:first, :conditions =>
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['id = ? and version = ?',
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elt.id, elt.version])
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unless elt.visible
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# if the element isn't visible then it must have been deleted, so
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# output the *previous* XML
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deleted = XML::Node.new "delete"
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deleted << prev_elt.to_xml_node
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else
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# must be a modify, for which we don't need the previous version
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# yet...
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modified = XML::Node.new "modify"
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modified << elt.to_xml_node
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end
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end
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end
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render :text => result.to_s, :content_type => "text/xml"
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rescue ActiveRecord::RecordNotFound
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render :nothing => true, :status => :not_found
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rescue OSM::APIError => ex
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render ex.render_opts
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end
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end
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