module Sequel::Plugins::List::InstanceMethods
Public Instance Methods
When destroying an instance, move all entries after the instance down one position, so that there aren't any gaps
# File lib/sequel/plugins/list.rb, line 101 def after_destroy super f = Sequel.expr(position_field) list_dataset.where(f > position_value).update(f => f - 1) end
The model object at the given position in the list containing this instance.
# File lib/sequel/plugins/list.rb, line 86 def at_position(p) list_dataset.first(position_field => p) end
Set the value of the #position_field to the maximum value plus 1 unless the position field already has a value.
# File lib/sequel/plugins/list.rb, line 92 def before_create unless get_column_value(position_field) set_column_value("#{position_field}=", list_dataset.max(position_field).to_i+1) end super end
Find the last position in the list containing this instance.
# File lib/sequel/plugins/list.rb, line 109 def last_position list_dataset.max(position_field).to_i end
A dataset that represents the list containing this instance.
# File lib/sequel/plugins/list.rb, line 114 def list_dataset model.scope_proc ? model.scope_proc.call(self) : model.dataset end
Move this instance down the given number of places in the list, or 1 place if no argument is specified.
# File lib/sequel/plugins/list.rb, line 120 def move_down(n = 1) move_to(position_value + n) end
Move this instance to the given place in the list. Raises an exception if target is less than 1 or greater than the last position in the list.
# File lib/sequel/plugins/list.rb, line 126 def move_to(target, lp = nil) current = position_value if target != current checked_transaction do ds = list_dataset op, ds = if target < current raise(Sequel::Error, "Moving too far up (target = #{target})") if target < 1 [:+, ds.filter(position_field=>target...current)] else lp ||= last_position raise(Sequel::Error, "Moving too far down (target = #{target}, last_position = #{lp})") if target > lp [:-, ds.filter(position_field=>(current + 1)..target)] end ds.update(position_field => Sequel::SQL::NumericExpression.new(op, position_field, 1)) update(position_field => target) end end self end
Move this instance to the bottom (last position) of the list.
# File lib/sequel/plugins/list.rb, line 147 def move_to_bottom lp = last_position move_to(lp, lp) end
Move this instance to the top (first position, position 1) of the list.
# File lib/sequel/plugins/list.rb, line 153 def move_to_top move_to(1) end
Move this instance the given number of places up in the list, or 1 place if no argument is specified.
# File lib/sequel/plugins/list.rb, line 159 def move_up(n = 1) move_to(position_value - n) end
The model instance the given number of places below this model instance in the list, or 1 place below if no argument is given.
# File lib/sequel/plugins/list.rb, line 165 def next(n = 1) n == 0 ? self : at_position(position_value + n) end
The value of the model's position field for this instance.
# File lib/sequel/plugins/list.rb, line 170 def position_value get_column_value(position_field) end
The model instance the given number of places below this model instance in the list, or 1 place below if no argument is given.
# File lib/sequel/plugins/list.rb, line 176 def prev(n = 1) self.next(n * -1) end
Private Instance Methods
The model's position field, an instance method for ease of use.
# File lib/sequel/plugins/list.rb, line 183 def position_field model.position_field end