Module: Edge::Forest::ClassMethods

Defined in:
lib/edge/forest.rb

Instance Method Summary collapse

Instance Method Details

#find_forest ⇒ Object

Finds entire forest and preloads all associations. It can be used at the end of an ActiveRecord finder chain.

Example:

# loads all locations
Location.find_forest

# loads all nodes with matching names and all there descendants
Category.where(:name => %w{clothing books electronics}).find_forest



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# File 'lib/edge/forest.rb', line 54

def find_forest
  new_scope = unscoped.joins("INNER JOIN all_nodes USING(#{connection.quote_column_name primary_key})")
  new_scope = new_scope.order(forest_order) if forest_order

  sql = "\#{cte_sql}\n\#{new_scope.to_sql}\n"
  records = find_by_sql sql

  records_by_id = records.each_with_object({}) { |r, h| h[r.id] = r }

  # Set all children associations to an empty array
  records.each do |r|
    children_association = r.association(:children)
    children_association.target = []
  end

  top_level_records = []

  records.each do |r|
    parent = records_by_id[r[forest_foreign_key]]
    if parent
      r.association(:parent).target = parent
      parent.association(:children).target.push(r)
    else
      top_level_records.push(r)
    end
  end

  top_level_records
end

#find_tree(id_or_ids) ⇒ Object

Finds an a tree or trees by id.

If any requested ids are not found it raises ActiveRecord::RecordNotFound.



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# File 'lib/edge/forest.rb', line 91

def find_tree(id_or_ids)
  trees = where(:id => id_or_ids).find_forest
  if id_or_ids.kind_of?(Array)
    raise ActiveRecord::RecordNotFound unless trees.size == id_or_ids.size
    trees
  else
    raise ActiveRecord::RecordNotFound if trees.empty?
    trees.first
  end
end

#with_descendants ⇒ Object

Returns a new scope that includes previously scoped records and their descendants by subsuming the previous scope into a subquery

Only where scopes can precede this in a scope chain



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# File 'lib/edge/forest.rb', line 105

def with_descendants
  subquery_scope = unscoped
    .joins("INNER JOIN all_nodes USING(#{connection.quote_column_name primary_key})")
    .select(primary_key)

  subquery_sql = "\#{cte_sql}\n\#{subquery_scope.to_sql}\n"

  unscoped.where "\#{connection.quote_column_name primary_key} IN (\#{subquery_sql})\n"
end