uses fast xml parsing ang generation with Nokogiri;
can import immadiately and in background job (using delayed job);
allows disable some fields and versions/milestones for sync (separately for import and export);
supports almost all attributes of tasks (hierarchy, status name (custom field), assignee, tracker (custom field), relations (preceses/follows), task name, description, estimated hrs, spent hrs, project, priority, redmine id (custom field), fixed version, link to redmine issue, …);
allows export whole project and custom query;
has flexible permissions setting;
allows preview and edit tasks before import in redmine;
email notification for author of import when import finished (sends only when import procedes as background job) without notifications for participants of tasks (no spam);
has ability to update existing tasks or forced create new.
Plugin initially based on redmine_loader plugin. Now almost completely rewritten.
cd redmine git clone firstname.lastname@example.org:m0n9oose/redmine_loader.git plugins/redmine_loader rake redmine:plugins:migrate RAILS_ENV=production
(migration needs for delayed job)
rake redmine:plugins:migrate NAME=redmine_loader VERSION=0 RAILS_ENV=production rm -Rf plugins/redmine_loader public/plugin_assets/redmine_loader
and restart redmine