Module: Glue::Orderable

Includes:
Aspects
Defined in:
lib/glue/orderable.rb

Overview

Attach list/ordering methods to the enchanted class.

Comments

If you use the scope option, you have to set he parent (scope) of the object before inserting to have correct ordering.

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.included_with_parameters(base, opt) ⇒ Object 



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# File 'lib/glue/orderable.rb', line 16

def self.included_with_parameters(base, opt)

  # The attribute to use to keep the position.
  
  opt_position = opt.fetch(:position, 'position')

  # The type of the position attribute.
  
  opt_type = opt.fetch(:type, Fixnum)

  # A user defined condition.
  
  opt_condition = opt[:condition]

  # A condition based on a key field (?)
  
  opt_scope = opt[:scope]

  # clean scope field.
  
  if opt_scope
    if opt_scope.to_s !~ /_oid$/
      opt_scope = "#{opt_scope}_oid".to_sym
    else
      opt_scope = opt_scope.to_sym
    end
  end

  base.module_eval %{
    attr_accessor :#{opt_position}, #{opt_type}

    def orderable_attribute
      #{opt_position.inspect}
    end
        
    def orderable_position
      @#{opt_position}
    end

    def orderable_position= (pos)
      @#{opt_position} = pos
    end

    def orderable_type
      #{opt_type}
    end
 
    def orderable_scope
      #{opt_scope.inspect}
    end

    def orderable_condition
      scope = orderable_scope
      if scope
        scope_value = send(scope)
        scope = scope_value ? "\#{scope} = \#{scope_value}" : "\#{scope} IS NULL"
      end
      return [ #{opt_condition.inspect}, scope ].compact
    end
  }

end

Instance Method Details

#add_to ⇒ Object 



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# File 'lib/glue/orderable.rb', line 154

def add_to
  # TODO
end

#add_to_bottom ⇒ Object 



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# File 'lib/glue/orderable.rb', line 150

def add_to_bottom
  self.orderable_position = bottom_position + 1
end

#add_to_top ⇒ Object 



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# File 'lib/glue/orderable.rb', line 146

def add_to_top
  increment_position_of_all_items
end

#bottom? ⇒ Boolean Also known as: last?

Returns:

  • (Boolean) 


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# File 'lib/glue/orderable.rb', line 190

def bottom?
  self.orderable_position == bottom_position
end

#bottom_item ⇒ Object 



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# File 'lib/glue/orderable.rb', line 177

def bottom_item
  pos = orderable_attribute
  con = orderable_condition
  con = con.empty? ? nil : con.join(' AND ')
  self.class.one(:condition => con, :order => "#{pos} DESC", :limit => 1)
end

#bottom_position ⇒ Object 



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# File 'lib/glue/orderable.rb', line 205

def bottom_position
  item = bottom_item
  item ? (item.orderable_position || 0) : 0
end

#decrement_position ⇒ Object 



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# File 'lib/glue/orderable.rb', line 200

def decrement_position
  self.orderable_position -= 1
  update_attribute(self.orderable_attribute)
end

#decrement_position_of_lower_items ⇒ Object 



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# File 'lib/glue/orderable.rb', line 233

def decrement_position_of_lower_items
  pos = orderable_attribute
  con = orderable_condition + [ "#{pos} > #{orderable_position}" ]
  self.class.update "#{pos}=(#{pos} - 1)",  :condition => con.join(' AND ')
end

#higher_item ⇒ Object Also known as: previous_item 



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# File 'lib/glue/orderable.rb', line 158

def higher_item
  pos = orderable_attribute
  con = orderable_condition + [ "#{pos} = #{orderable_position - 1}" ]
  self.class.one( :condition => con.join(' AND ') )
end

#increment_position ⇒ Object 



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# File 'lib/glue/orderable.rb', line 195

def increment_position
  self.orderable_position += 1
  update_attribute(self.orderable_attribute)
end

#increment_position_of_all_items ⇒ Object 



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# File 'lib/glue/orderable.rb', line 226

def increment_position_of_all_items
  pos = orderable_attribute
  con = orderable_condition
  con = con.empty? ? nil : con.join(' AND ')
  self.class.update "#{pos}=(#{pos} + 1)", :condition => con 
end

#increment_position_of_higher_items ⇒ Object 



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# File 'lib/glue/orderable.rb', line 220

def increment_position_of_higher_items
  pos = orderable_attribute
  con = orderable_condition + [ "#{pos} < #{orderable_position}" ]
  self.class.update "#{pos}=(#{pos} + 1)",  :condition => con.join(' AND ')
end

#lower_item ⇒ Object Also known as: next_item 



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# File 'lib/glue/orderable.rb', line 165

def lower_item
  pos = orderable_attribute
  con = orderable_condition + [ "#{pos} = #{orderable_position + 1}" ]
  self.class.one( :condition => con.join(' AND ') )
end

#move_higher ⇒ Object

Move higher.



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# File 'lib/glue/orderable.rb', line 84

def move_higher
  if higher = higher_item
    self.class.transaction do
      higher.increment_position
      decrement_position
    end
  end
end

#move_lower ⇒ Object

Move lower.



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# File 'lib/glue/orderable.rb', line 95

def move_lower
  if lower = lower_item
    self.class.transaction do
      lower.decrement_position
      increment_position
    end
  end
end

#move_to(dest_position) ⇒ Object

Move to a specific position.



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# File 'lib/glue/orderable.rb', line 124

def move_to(dest_position)
  return if self.orderable_position == dest_position

  pos = orderable_attribute
  con = orderable_condition

  self.class.transaction do
    if orderable_position < dest_position
      adj = "#{pos} = #{pos} - 1"
      con = con + [ "#{pos} > #{orderable_position}", "#{pos} <= #{dest_position}" ]
    else
      adj = "#{pos} = #{pos} + 1"
      con = con + [ "#{pos} < #{orderable_position}", "#{pos} >= #{dest_position}" ]
    end
    self.class.update( adj, :condition => con.join(' AND ') )
    self.orderable_position = dest_position
    update_attribute(orderable_attribute)
  end

  self
end

#move_to_bottom ⇒ Object

Move to the bottom.



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# File 'lib/glue/orderable.rb', line 115

def move_to_bottom
  self.class.transaction do
    decrement_position_of_lower_items
    set_bottom_position
  end
end

#move_to_top ⇒ Object

Move to the top.



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# File 'lib/glue/orderable.rb', line 106

def move_to_top
  self.class.transaction do
    increment_position_of_higher_items
    set_top_position
  end
end

#set_bottom_position ⇒ Object 



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# File 'lib/glue/orderable.rb', line 215

def set_bottom_position
  self.orderable_position = bottom_position + 1
  update_attribute(orderable_attribute)
end

#set_top_position ⇒ Object 



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# File 'lib/glue/orderable.rb', line 210

def set_top_position
  self.orderable_position = 1
  update_attribute(orderable_attribute)
end

#top? ⇒ Boolean Also known as: first?

Returns:

  • (Boolean) 


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# File 'lib/glue/orderable.rb', line 185

def top?
  self.orderable_position == 1
end

#top_item ⇒ Object Also known as: first_item 



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# File 'lib/glue/orderable.rb', line 172

def top_item
  # TODO
end