尝试在ActiveAdmin中查看树时，会抛出错误：
undefined method 'sort_option' for :ancestry:Symbol
这不适用于组合：Mongoid，mongoid-ancestry和active_admin-sortable_tree 但适用于ActiveRecord，Ancestry和active_admin-sortable_tree
示例源代码位于：https://github.com/nahankid/community
违规代码段
def order_by(*spec) option(spec) do |options, query| spec.compact.each do |criterion| criterion.__sort_option__.each_pair do |field, direction| add_sort_option(options, field, direction) end
跟踪（不完整）
> ActionView::Template::Error (undefined method `__sort_option__' for
> :ancestry:Symbol):
> 1: insert_tag renderer_for(:index) origin (2.1.1) lib/origin/optional.rb:173:in `block (2 levels) in order_by' origin
> (2.1.1) lib/origin/optional.rb:172:in `each' origin (2.1.1)
> lib/origin/optional.rb:172:in `block in order_by' origin (2.1.1)
> lib/origin/optional.rb:314:in `block in option' origin (2.1.1)
> lib/origin/optional.rb:312:in `tap' origin (2.1.1)
> lib/origin/optional.rb:312:in `option' origin (2.1.1)
> lib/origin/optional.rb:171:in `order_by' active_admin-sortable_tree
> (0.2.0) lib/active_admin/views/index_as_sortable.rb:139:in `block (2
> levels) in build_nested_item' arbre (1.0.3)
> lib/arbre/element/builder_methods.rb:31:in `block in build_tag'
> arbre (1.0.3) lib/arbre/context.rb:92:in `with_current_arbre_element'
> arbre (1.0.3) lib/arbre/element/builder_methods.rb:49:in
> `with_current_arbre_element' arbre (1.0.3)
> lib/arbre/element/builder_methods.rb:26:in `build_tag' arbre (1.0.3)
> lib/arbre/element/builder_methods.rb:39:in `insert_tag' arbre
> (1.0.3) lib/arbre/element/builder_methods.rb:14:in `ol'
> active_admin-sortable_tree (0.2.0)
> lib/active_admin/views/index_as_sortable.rb:138:in `block in
> build_nested_item' arbre (1.0.3)
> lib/arbre/element/builder_methods.rb:31:in `block in build_tag'
> arbre (1.0.3) lib/arbre/context.rb:92:in `with_current_arbre_element'
> arbre (1.0.3) lib/arbre/element/builder_methods.rb:49:in
> `with_current_arbre_element' arbre (1.0.3)
> lib/arbre/element/builder_methods.rb:26:in `build_tag' arbre (1.0.3)
> lib/arbre/element/builder_methods.rb:39:in `insert_tag' arbre
> (1.0.3) lib/arbre/element/builder_methods.rb:14:in `li'
> active_admin-sortable_tree (0.2.0)
> lib/active_admin/views/index_as_sortable.rb:117:in `build_nested_item'
> active_admin-sortable_tree (0.2.0)
> lib/active_admin/views/index_as_sortable.rb:86:in `block (2 levels) in
> build_list' active_admin-sortable_tree (0.2.0)
> lib/active_admin/views/index_as_sortable.rb:85:in `each'
> active_admin-sortable_tree (0.2.0)
> lib/active_admin/views/index_as_sortable.rb:85:in `block in
> build_list' arbre (1.0.3) lib/arbre/element/builder_methods.rb:31:in
> `block in build_tag' arbre (1.0.3) lib/arbre/context.rb:92:in
> `with_current_arbre_element' arbre (1.0.3)
> lib/arbre/element/builder_methods.rb:49:in
> `with_current_arbre_element' arbre (1.0.3)
> lib/arbre/element/builder_methods.rb:26:in `build_tag' arbre (1.0.3)
> lib/arbre/element/builder_methods.rb:39:in `insert_tag' arbre
> (1.0.3) lib/arbre/element/builder_methods.rb:14:in `ol'
> active_admin-sortable_tree (0.2.0)
> lib/active_admin/views/index_as_sortable.rb:84:in `build_list'
> active_admin-sortable_tree (0.2.0)
> lib/active_admin/views/index_as_sortable.rb:23:in `build' arbre
> (1.0.3) lib/arbre/element/builder_methods.rb:30:in `block in
> build_tag' arbre (1.0.3) lib/arbre/context.rb:92:in
> `with_current_arbre_element' arbre (1.0.3)
> lib/arbre/element/builder_methods.rb:49:in
> `with_current_arbre_element' arbre (1.0.3)
> lib/arbre/element/builder_methods.rb:26:in `build_tag' arbre (1.0.3)
> lib/arbre/element/builder_methods.rb:39:in `insert_tag'
> /usr/local/rvm/gems/ruby-2.1.5@rails4/bundler/gems/active_admin-2e5e954bc9b1/lib/active_admin/views/pages/index.rb:139:in
> `block (2 levels) in render_index' arbre (1.0.3)
> lib/arbre/element/builder_methods.rb:31:in `block in build_tag'
> arbre (1.0.3) lib/arbre/context.rb:92:in `with_current_arbre_element'
> arbre (1.0.3) lib/arbre/element/builder_methods.rb:49:in
> `with_current_arbre_element' arbre (1.0.3)
> lib/arbre/element/builder_methods.rb:26:in `build_tag' arbre (1.0.3)
> lib/arbre/element/builder_methods.rb:39:in `insert_tag' arbre
> (1.0.3) lib/arbre/element/builder_methods.rb:14:in `div'
> /usr/local/rvm/gems/ruby-2.1.5@rails4/bundler/gems/active_admin-2e5e954bc9b1/lib/active_admin/views/pages/index.rb:138:in
> `block in render_index' ar
答案 0 :(得分：0)
这里的罪犯是active_admin-sortable树。假设您使用的是ActiveRecord，并且不符合Mongoid的排序语法。
在Mongoid中，您必须指定排序的方向，1或-1表示升序或降序。这是因为如果没有提供方向，MongoDB的查询语法没有对排序方向的假设，这与SQL假定如果没有给出升序那样假设。
所以当宝石在这里调用order时：
它没有提供方向。如果是这样的话：
item.send(options[:children_method]).order(options[:sorting_attribute] => :asc).each do |c|
然后它将兼容两者，至少仅在这种情况下。我不确定那个宝石会有什么其他问题。