module Sequel::Plugins::List::InstanceMethods

Public Instance Methods

after_destroy() click to toggle source

When destroying an instance, move all entries after the instance down one position, so that there aren't any gaps

Calls superclass method
# File lib/sequel/plugins/list.rb, line 94
def after_destroy
  super

  f = Sequel[position_field]
  list_dataset.where(f > position_value).update(f => f - 1)
end
at_position(p) click to toggle source

The model object at the given position in the list containing this instance.

# File lib/sequel/plugins/list.rb, line 88
def at_position(p)
  list_dataset.first(position_field => p)
end
last_position() click to toggle source

Find the last position in the list containing this instance.

# File lib/sequel/plugins/list.rb, line 102
def last_position
  list_dataset.max(position_field).to_i
end
list_dataset() click to toggle source

A dataset that represents the list containing this instance.

# File lib/sequel/plugins/list.rb, line 107
def list_dataset
  model.scope_proc ? model.scope_proc.call(self) : model.dataset
end
move_down(n = 1) click to toggle source

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 113
def move_down(n = 1)
  move_to(position_value + n)
end
move_to(target, lp = nil) click to toggle source

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 119
def move_to(target, lp = nil)
  current = position_value
  if target != current
    checked_transaction do
      ds = list_dataset
      op, ds = if target < current
        target = 1 if target < 1
        [:+, ds.where(position_field=>target...current)]
      else
        lp ||= last_position
        target = lp if target > lp
        [:-, ds.where(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_to_bottom() click to toggle source

Move this instance to the bottom (last position) of the list.

# File lib/sequel/plugins/list.rb, line 140
def move_to_bottom
  lp = last_position 
  move_to(lp, lp)
end
move_to_top() click to toggle source

Move this instance to the top (first position, position 1) of the list.

# File lib/sequel/plugins/list.rb, line 146
def move_to_top
  move_to(1)
end
move_up(n = 1) click to toggle source

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 152
def move_up(n = 1)
  move_to(position_value - n) 
end
next(n = 1) click to toggle source

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 158
def next(n = 1)
  n == 0 ? self : at_position(position_value + n)
end
position_value() click to toggle source

The value of the model's position field for this instance.

# File lib/sequel/plugins/list.rb, line 163
def position_value
  get_column_value(position_field)
end
prev(n = 1) click to toggle source

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 169
def prev(n = 1)
  self.next(n * -1)
end

Private Instance Methods

_before_validation() click to toggle source

Set the value of the #position_field to the maximum value plus 1 unless the position field already has a value.

Calls superclass method
# File lib/sequel/plugins/list.rb, line 177
def _before_validation
  unless get_column_value(position_field)
    set_column_value("#{position_field}=", list_dataset.max(position_field).to_i+1)
  end
  super
end
position_field() click to toggle source

The model's position field, an instance method for ease of use.

# File lib/sequel/plugins/list.rb, line 185
def position_field
  model.position_field
end