def to_json(*a)
      { :item => if item then
                   item.name
                 else
                   nil
                 end,
        :tag  => if tag then
                   tag.name
                 else
                   nil
                 end,
        :src  => path_from_catalog_root }.to_json(*a)
    end
def to_json(*a)
      { :item => if item then
                   item.name
                 else
                   nil
                 end,
        :tag  => if tag then
                   tag.name
                 else
                   nil
                 end,
        :src  => path_from_catalog_root }.to_json(*a)
    end
:required => false