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Create api changeset download resource

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This commit is contained in:
Anton Khorev 2025-02-20 03:41:04 +03:00
parent 1f1a20e539
commit 49fac49f9d
9 changed files with 166 additions and 143 deletions
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52
app/controllers/api/changesets_controller.rb
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@ -130,58 +130,6 @@ module Api
end
end
##
# 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_by! { |e| [e.timestamp, e.version] }
# 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.
@created = []
@modified = []
@deleted = []
elements.each do |elt|
if elt.version == 1
# first version, so it must be newly-created.
@created << elt
elsif elt.visible
# must be a modify
@modified << elt
else
# if the element isn't visible then it must have been deleted
@deleted << elt
end
end
respond_to do |format|
format.xml
end
end
##
# updates a changeset's tags. none of the changeset's attributes are
# user-modifiable, so they will be ignored.