[See ckan/ckan#1006 Issue has been solved. Might have been a SQLite related problem.]

It demonstrates a problem with the CKAN 3 stages model of editing and storing a dataset. If you try to add custom metadata in stage 1 and stage 3, the one in stage 3 does not get stored, if you use 'convert_to_extras'. (see this thread: http://lists.okfn.org/pipermail/ckan-dev/2013-May/004782.html).

This example simply uses the ckan extension integrated in CKAN (example_idatasetform) and adds a custom metadata field to stage 3 (templates/package/snippets/package_metadata_fields.html) and to the plugin class.