+
+ ##
+ # subset of consistency checks which should be applied to almost
+ # all the changeset controller's writable methods.
+ def check_changeset_consistency(changeset, user)
+ # check user credentials - only the user who opened a changeset
+ # may alter it.
+ if changeset.nil?
+ raise OSM::APIChangesetMissingError.new
+ elsif user.id != changeset.user_id
+ raise OSM::APIUserChangesetMismatchError.new
+ elsif not changeset.is_open?
+ raise OSM::APIChangesetAlreadyClosedError.new(changeset)
+ end
+ end