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treeify.rb
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treeify.rb
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require 'active_record'
require 'pp'
require "active_support/concern"
require "active_support/core_ext/module/attribute_accessors"
require "active_support/core_ext/class/attribute"
module Treeify
extend ActiveSupport::Concern
cattr_writer :cols do
[]
end
included do
has_many :children,
class_name: self,
foreign_key: "parent_id"
belongs_to :parent,
class_name: self,
foreign_key: "parent_id"
class_attribute :cols
scope :roots, -> { where(parent_id: nil) }
scope :tree_for, ->(instance) { self.find_by_sql self.tree_sql_for(instance) }
scope :tree_for_ancestors, ->(instance) { self.find_by_sql self.tree_sql_for_ancestors(instance) }
end
module ClassMethods
def tree_config(hash = {})
self.cols = !hash[:cols].nil? == true ? hash[:cols] : []
end
def columns_joined(char=",")
self.cols ||= []
self.cols.join(char)
end
def columns_with_table_name
self.cols ||= []
self.cols.map{|c|
c = "#{table_name}.#{c}"
}.join(",")
end
def has_config_defined_cols?
#return true if self.respond_to?("cols") && !self.cols.nil?
if self.respond_to?("cols")
return !self.cols.empty? if !self.cols.nil?
end
false
end
# sort of hacky, but check to see if we have any columns defined in the config
# if we do, return the string of columns, formatted appropriately
# otherwise, just return an empty string
def appropriate_column_listing(columns = columns_joined)
has_config_defined_cols? == true ? ", #{columns}" : ""
end
def tree_sql(instance)
cte_params = has_config_defined_cols? ? "id, parent_id, path, #{columns_joined}" : "id, parent_id, path"
"WITH RECURSIVE cte (#{cte_params}) AS (
SELECT id,
parent_id,
array[id] AS path#{appropriate_column_listing}
FROM #{table_name}
WHERE id = #{instance.id}
UNION ALL
SELECT #{table_name}.id,
#{table_name}.parent_id,
cte.path || #{table_name}.id#{appropriate_column_listing(columns_with_table_name)}
FROM #{table_name}
JOIN cte ON #{table_name}.parent_id = cte.id
)"
end
def tree_sql_for(instance)
"#{tree_sql(instance)}
SELECT * FROM cte
ORDER BY path"
end
def tree_sql_for_ancestors(instance)
"#{tree_sql(instance)}
SELECT * FROM cte
WHERE cte.id != #{instance.id}"
end
end
def descendents
self_and_descendents - [self]
end
def ancestors
self.class.tree_for_ancestors(self)
end
def self_and_descendents
self.class.tree_for(self)
end
def is_root?
self.parent_id != nil
end
def siblings
self.class.where(parent_id: self.parent_id) - [self]
end
def descendent_tree
# give build_tree an array of hashes with the AR objects serialized into a hash
build_tree(descendents.to_a.map(&:serializable_hash))
end
def build_tree(data)
# turn our AoH into a hash where we've mapped the ID column
# to the rest of the hash + a comments array for nested comments
nested_hash = Hash[data.map{|e| [e['id'], e.merge('children' => [])]}]
# if we have a parent ID, grab all the comments
# associated with that parent and push them into the comments array
nested_hash.each do |id, item|
parent = nested_hash[item['parent_id']]
parent['children'] << item if parent
end
# return the values of our nested hash, ie our actual comment hash data
# reject any descendents whose parent ID already exists in the main hash so we don't
# get orphaned descendents listed as their own comment
nested_hash.reject{|id, item|
nested_hash.has_key? item['parent_id']
}.values
end
end