On Wednesday, September 9, 2020 at 6:03:53 PM UTC-7, abhijit wrote:
>
> Hi,
>
> I have a table with associations to itself in a parent child hierarchy
> using parent_id as the foreign key. I can use both the *tree* and the
> *rcte_tree* Sequel plugins there.
>
> I need to get all the children in a nested format, so I've written a
> method like this -
>
> class User < Sequel::Model(:users)
> plugin :rcte_tree
>
> def get_all_children
> below = []
>
> if self.children.count.zero?
> below = nil
> else
> self.children.each do |child|
> ret = child.get_all_children
> below.push ret
> end
> end
>
> self.values.merge({children: below})
> end
> end
>
> And I'm able to get the response as expected -
>
> ---
> :id: 1
> :name: AAA
> :parent_id: nil
> :children:
> - :id: 2
> :name: AA1
> :parent_id: 1
> :children:
> - :id: 3
> :name: AA2
> :parent_id: 2
> :children: nil
>
>
> I was wondering if there is a better way to do this.
>
If you use the rcte_tree plugin, it should be able to retrieve all
descendants in a single database query. Here's a more compact version:
class User < Sequel::Model(:users)
plugin :rcte_tree
def get_all_children
descendants unless children
values.merge(children: (children.map(&:get_all_children) unless
children.empty?))
end
end
Thanks,
Jeremy
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