forked from fixin.me/fixin.me
70 lines
2.3 KiB
Ruby
70 lines
2.3 KiB
Ruby
class Quantity < ApplicationRecord
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belongs_to :user, optional: true
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belongs_to :parent, optional: true, class_name: "Quantity"
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has_many :subquantities, class_name: "Quantity", inverse_of: :parent,
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dependent: :restrict_with_error
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validate if: ->{ parent.present? } do
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errors.add(:parent, :user_mismatch) unless user == parent.user
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end
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validates :name, presence: true, length: {maximum: type_for_attribute(:name).limit}
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validates :description, length: {maximum: type_for_attribute(:description).limit}
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scope :defaults, ->{ where(user: nil) }
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scope :ordered, ->{
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numbered = Arel::Table.new('numbered')
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Quantity.with(numbered: numbered(:parent_id, :name)).with_recursive(quantities: [
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Arel::SelectManager.new.project(
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numbered[Arel.star],
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numbered.cast(numbered[:child_number], 'BINARY').as('path'),
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Arel::Nodes.build_quoted(0).as('depth')
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).from(numbered).where(numbered[:parent_id].eq(nil)),
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Arel::SelectManager.new.project(
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numbered[Arel.star],
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arel_table[:path].concat(numbered[:child_number]),
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arel_table[:depth] + 1
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).from(numbered).join(arel_table).on(numbered[:parent_id].eq(arel_table[:id]))
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]).select(arel_table[Arel.star]).from(arel_table).order(arel_table[:path])
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}
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# TODO: extract named functions to custom Arel extension
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# https://gist.github.com/ProGM/c6df08da14708dcc28b5ca325df37ceb#extending-arel
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scope :numbered, ->(parent_column, order_column){
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select(
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arel_table[Arel.star],
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Arel::Nodes::NamedFunction.new(
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'LPAD',
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[
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Arel::Nodes::NamedFunction.new('ROW_NUMBER', [])
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.over(Arel::Nodes::Window.new.partition(parent_column).order(order_column)),
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Arel::SelectManager.new.project(
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Arel::Nodes::NamedFunction.new('LENGTH', [Arel.star.count])])
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),
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Arel::Nodes.build_quoted('0')
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],
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).as('child_number')
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)
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}
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def to_s
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name
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end
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def movable?
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subunits.empty?
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end
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def default?
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parent_id.nil?
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end
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def successive
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quantities = Quantity.arel_table
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Quantity.with(
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quantities: user.quantities.ordered.select(
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Arel::Nodes::NamedFunction.new('LAG', [quantities[:id]]).over.as('lag_id')
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)
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).where(quantities[:lag_id].eq(id)).first
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end
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end
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