module Sequel::Plugins::Tree
The Tree plugin adds additional associations and methods that allow you to treat a Model as a tree.
A column for holding the parent key is required and is :parent_id by default.
This may be overridden by passing column name via :key.
Optionally, a column to control order of nodes returned can be specified by passing column name via :order.
If you pass true for the :single_root option, the class will ensure there is only ever one root in the tree.
Examples:
class Node < Sequel::Model plugin :tree end class Node < Sequel::Model plugin :tree, :key=>:parentid, :order=>:position end
Public Class Methods
apply(model, opts=OPTS)
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Create parent and children associations. Any options specified are passed to both associations. You can also specify options to use for just the parent association using a :parent option, and options to use for just the children association using a :children option.
# File lib/sequel/plugins/tree.rb, line 32 def self.apply(model, opts=OPTS) opts = opts.dup opts[:class] = model model.instance_eval do @parent_column = (opts[:key] ||= :parent_id) @tree_order = opts[:order] end par = opts.merge(opts.fetch(:parent, {})) parent = par.fetch(:name, :parent) chi = opts.merge(opts.fetch(:children, {})) children = chi.fetch(:name, :children) par[:reciprocal] = children chi[:reciprocal] = parent model.many_to_one parent, par model.one_to_many children, chi model.plugin SingleRoot if opts[:single_root] end