Module: Sequel::Plugins::List::InstanceMethods

Defined in:
lib/sequel/plugins/list.rb

Instance Method Summary collapse

Instance Method Details

#after_destroy ⇒ Object

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



106
107
108
109
110
111
 
# File 'lib/sequel/plugins/list.rb', line 106

def after_destroy
  super

  f = Sequel[position_field]
  list_dataset.where(f > position_value).update(f => f - 1)
end

#at_position(p) ⇒ Object

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



100
101
102
 
# File 'lib/sequel/plugins/list.rb', line 100

def at_position(p)
  list_dataset.first(position_field => p)
end

#before_validation ⇒ Object

Set the value of the position_field to the maximum value plus 1 unless the position field already has a value. If the list is empty, the position will be set to the model’s top_of_list value.



190
191
192
193
194
195
196
197
 
# File 'lib/sequel/plugins/list.rb', line 190

def before_validation
  unless get_column_value(position_field)
    current_max = list_dataset.max(position_field)
    value = current_max.nil? ? model.top_of_list : current_max.to_i + 1
    set_column_value("#{position_field}=", value)
  end
  super
end

#last_position ⇒ Object

Find the last position in the list containing this instance.



114
115
116
 
# File 'lib/sequel/plugins/list.rb', line 114

def last_position
  list_dataset.max(position_field).to_i
end

#list_dataset ⇒ Object

A dataset that represents the list containing this instance.



119
120
121
 
# File 'lib/sequel/plugins/list.rb', line 119

def list_dataset
  model.scope_proc ? model.scope_proc.call(self) : model.dataset
end

#move_down(n = 1) ⇒ Object

Move this instance down the given number of places in the list, or 1 place if no argument is specified.



125
126
127
 
# File 'lib/sequel/plugins/list.rb', line 125

def move_down(n = 1)
  move_to(position_value + n)
end

#move_to(target, lp = nil) ⇒ Object

Move this instance to the given place in the list. If lp is not given or greater than the last list position, uses the last list position. If lp is less than the top list position, uses the top list position.



133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
 
# File 'lib/sequel/plugins/list.rb', line 133

def move_to(target, lp = nil)
  current = position_value
  if target != current
    checked_transaction do
      ds = list_dataset
      op, ds = if target < current
        target = model.top_of_list if target < model.top_of_list
        [:+, 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 ⇒ Object

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



154
155
156
157
 
# File 'lib/sequel/plugins/list.rb', line 154

def move_to_bottom
  lp = last_position 
  move_to(lp, lp)
end

#move_to_top ⇒ Object

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



160
161
162
 
# File 'lib/sequel/plugins/list.rb', line 160

def move_to_top
  move_to(model.top_of_list)
end

#move_up(n = 1) ⇒ Object

Move this instance the given number of places up in the list, or 1 place if no argument is specified.



166
167
168
 
# File 'lib/sequel/plugins/list.rb', line 166

def move_up(n = 1)
  move_to(position_value - n) 
end

#next(n = 1) ⇒ Object

The model instance the given number of places below this model instance in the list, or 1 place below if no argument is given.



172
173
174
 
# File 'lib/sequel/plugins/list.rb', line 172

def next(n = 1)
  n == 0 ? self : at_position(position_value + n)
end

#position_value ⇒ Object

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



177
178
179
 
# File 'lib/sequel/plugins/list.rb', line 177

def position_value
  get_column_value(position_field)
end

#prev(n = 1) ⇒ Object

The model instance the given number of places below this model instance in the list, or 1 place below if no argument is given.



183
184
185
 
# File 'lib/sequel/plugins/list.rb', line 183

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