- ##
- # download the changeset as an osmChange document.
- #
- # to make it easier to revert diffs it would be better if the osmChange
- # format were reversible, i.e: contained both old and new versions of
- # modified elements. but it doesn't at the moment...
- #
- # this method cannot order the database changes fully (i.e: timestamp and
- # version number may be too coarse) so the resulting diff may not apply
- # to a different database. however since changesets are not atomic this
- # behaviour cannot be guaranteed anyway and is the result of a design
- # choice.
- def download
- changeset = Changeset.find(params[:id])
-
- # get all the elements in the changeset which haven't been redacted
- # and stick them in a big array.
- elements = [changeset.old_nodes.unredacted,
- changeset.old_ways.unredacted,
- changeset.old_relations.unredacted].flatten
-
- # sort the elements by timestamp and version number, as this is the
- # almost sensible ordering available. this would be much nicer if
- # global (SVN-style) versioning were used - then that would be
- # unambiguous.
- elements.sort! do |a, b|
- if a.timestamp == b.timestamp
- a.version <=> b.version
- else
- a.timestamp <=> b.timestamp
- end
- end
-
- # create changeset and user caches
- changeset_cache = {}
- user_display_name_cache = {}
-
- # create an osmChange document for the output
- result = OSM::API.new.get_xml_doc
- result.root.name = "osmChange"
-
- # generate an output element for each operation. note: we avoid looking
- # at the history because it is simpler - but it would be more correct to
- # check these assertions.
- elements.each do |elt|
- result.root <<
- if elt.version == 1
- # first version, so it must be newly-created.
- created = XML::Node.new "create"
- created << elt.to_xml_node(changeset_cache, user_display_name_cache)
- elsif elt.visible
- # must be a modify
- modified = XML::Node.new "modify"
- modified << elt.to_xml_node(changeset_cache, user_display_name_cache)
- else
- # if the element isn't visible then it must have been deleted
- deleted = XML::Node.new "delete"
- deleted << elt.to_xml_node(changeset_cache, user_display_name_cache)
- end
- end
-
- render :xml => result.to_s
- end
-
- ##
- # query changesets by bounding box, time, user or open/closed status.
- def query
- # find any bounding box
- bbox = BoundingBox.from_bbox_params(params) if params["bbox"]
-
- # create the conditions that the user asked for. some or all of
- # these may be nil.
- changesets = Changeset.all
- changesets = conditions_bbox(changesets, bbox)
- changesets = conditions_user(changesets, params["user"], params["display_name"])
- changesets = conditions_time(changesets, params["time"])
- changesets = conditions_open(changesets, params["open"])
- changesets = conditions_closed(changesets, params["closed"])
- changesets = conditions_ids(changesets, params["changesets"])
-
- # sort and limit the changesets
- changesets = changesets.order("created_at DESC").limit(100)
-
- # preload users, tags and comments, and render result
- @changesets = changesets.preload(:user, :changeset_tags, :comments)
- render "changesets"
- end
-