Module: Sortifiable::InstanceMethods

Defined in:
lib/sortifiable.rb

Overview

All the methods available to a record that has had acts_as_list specified. Each method works by assuming the object to be the item in the list, so chapter.move_lower would move that chapter lower in the list of all chapters. Likewise, chapter.first? would return true if that chapter is the first in the list of all chapters.

Instance Method Summary collapse

Instance Method Details

#add_to_list ⇒ Object

Add the item to the end of the list



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# File 'lib/sortifiable.rb', line 104

def add_to_list
  if in_list?
    move_to_bottom
  else
    list_class.transaction do
      ids = lock_list!
      last_position = ids.size
      if persisted?
        update_position last_position + 1
      else
        set_position last_position + 1
      end
    end
  end
end

#current_position ⇒ Object

Returns the current position



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# File 'lib/sortifiable.rb', line 121

def current_position
  send(position_column).to_i
end

#decrement_position ⇒ Object

Decrease the position of this item without adjusting the rest of the list.



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# File 'lib/sortifiable.rb', line 126

def decrement_position
  in_list? && update_position(current_position - 1)
end

#first? ⇒ Boolean Also known as: top?

Return true if this object is the first in the list.

Returns:

  • (Boolean) 


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# File 'lib/sortifiable.rb', line 131

def first?
  in_list? && current_position == 1
end

#first_item ⇒ Object Also known as: top_item

Returns the first item in the list



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# File 'lib/sortifiable.rb', line 137

def first_item
  list_scope.first
end

#higher_item ⇒ Object Also known as: previous_item

Return the next higher item in the list.



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# File 'lib/sortifiable.rb', line 143

def higher_item
  item_at_offset(-1)
end

#higher_items ⇒ Object

Return items lower than this item or an empty array if it is the last item



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# File 'lib/sortifiable.rb', line 149

def higher_items
  list_scope.where(["#{quoted_position_column} < ?", current_position]).to_a
end

#in_list? ⇒ Boolean

Test if this record is in a list

Returns:

  • (Boolean) 


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# File 'lib/sortifiable.rb', line 154

def in_list?
  !new_record? && !send(position_column).nil?
end

#increment_position ⇒ Object

Increase the position of this item without adjusting the rest of the list.



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# File 'lib/sortifiable.rb', line 164

def increment_position
  in_list? && update_position(current_position + 1)
end

#insert_at(position = 1) ⇒ Object

Insert the item at the given position (defaults to the top position of 1).



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# File 'lib/sortifiable.rb', line 169

def insert_at(position = 1)
  list_class.transaction do
    ids = lock_list!
    position = [[1, position].max, ids.size].min

    if persisted?
      current_position = ids.index(id) + 1

      sql = <<-SQL
        #{quoted_position_column} = CASE
        WHEN #{quoted_position_column} = #{current_position} THEN #{position}
        WHEN #{quoted_position_column} > #{current_position}
        AND #{quoted_position_column} <= #{position} THEN #{quoted_position_column} - 1
        WHEN #{quoted_position_column} < #{current_position}
        AND #{quoted_position_column} >= #{position} THEN #{quoted_position_column} + 1
        ELSE #{quoted_position_column}
        END
      SQL

      list_scope.update_all(sql)
      update_position(position)
    else
      save!

      sql = <<-SQL
        #{quoted_position_column} = CASE
        WHEN #{quoted_position_column} >= #{position} THEN #{quoted_position_column} + 1
        ELSE #{quoted_position_column}
        END
      SQL

      list_scope.update_all(sql)
      update_position(position)
    end
  end
end

#item_at_offset(offset) ⇒ Object

Return the item at the offset specified from the current position



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# File 'lib/sortifiable.rb', line 207

def item_at_offset(offset)
  in_list? ? offset_scope(offset).first : nil
end

#last? ⇒ Boolean Also known as: bottom?

Return true if this object is the last in the list.

Returns:

  • (Boolean) 


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# File 'lib/sortifiable.rb', line 212

def last?
  in_list? && current_position == last_position
end

#last_item ⇒ Object Also known as: bottom_item

Returns the bottom item



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# File 'lib/sortifiable.rb', line 218

def last_item
  list_scope.last
end

#last_position ⇒ Object Also known as: bottom_position

Returns the bottom position in the list.



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# File 'lib/sortifiable.rb', line 224

def last_position
  last_item.try(:current_position) || 0
end

#lower_item ⇒ Object Also known as: next_item

Return the next lower item in the list.



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# File 'lib/sortifiable.rb', line 230

def lower_item
  item_at_offset(1)
end

#lower_items ⇒ Object

Return items lower than this item or an empty array if it is the last item



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# File 'lib/sortifiable.rb', line 236

def lower_items
  list_scope.where(["#{quoted_position_column} > ?", current_position]).to_a
end

#move_higher ⇒ Object Also known as: move_up

Swap positions with the next higher item, if one exists.



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# File 'lib/sortifiable.rb', line 241

def move_higher
  if in_list?
    list_class.transaction do
      ids = lock_list!
      current_position = ids.index(id) + 1

      if current_position > 1
        sql = <<-SQL
          #{quoted_position_column} = CASE
          WHEN #{quoted_position_column} = #{current_position} - 1 THEN #{current_position}
          WHEN #{quoted_position_column} = #{current_position} THEN #{current_position} - 1
          ELSE #{quoted_position_column}
          END
        SQL

        set_position current_position - 1
        list_scope.update_all(sql) > 0
      else
        true
      end
    end
  else
    false
  end
end

#move_lower ⇒ Object Also known as: move_down

Swap positions with the next lower item, if one exists.



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# File 'lib/sortifiable.rb', line 269

def move_lower
  if in_list?
    list_class.transaction do
      ids = lock_list!
      current_position, last_position = ids.index(id) + 1, ids.size

      if current_position < last_position
        sql = <<-SQL
          #{quoted_position_column} = CASE
          WHEN #{quoted_position_column} = #{current_position} + 1 THEN #{current_position}
          WHEN #{quoted_position_column} = #{current_position} THEN #{current_position} + 1
          ELSE #{quoted_position_column}
          END
        SQL

        set_position current_position + 1
        list_scope.update_all(sql) > 0
      else
        true
      end
    end
  else
    false
  end
end

#move_to_bottom ⇒ Object

Move to the bottom of the list. If the item is already in the list, the items below it have their position adjusted accordingly.



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# File 'lib/sortifiable.rb', line 298

def move_to_bottom
  if in_list?
    list_class.transaction do
      ids = lock_list!
      current_position, last_position = ids.index(id) + 1, ids.size

      if current_position < last_position
        sql = <<-SQL
          #{quoted_position_column} = CASE
          WHEN #{quoted_position_column} = #{current_position} THEN #{last_position}
          WHEN #{quoted_position_column} > #{current_position} THEN #{quoted_position_column} - 1
          ELSE #{quoted_position_column}
          END
        SQL

        set_position last_position
        list_scope.update_all(sql) > 0
      else
        true
      end
    end
  else
    false
  end
end

#move_to_top ⇒ Object

Move to the top of the list. If the item is already in the list, the items above it have their position adjusted accordingly.



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# File 'lib/sortifiable.rb', line 326

def move_to_top
  if in_list?
    list_class.transaction do
      ids = lock_list!
      current_position = ids.index(id) + 1

      if current_position > 1
        sql = <<-SQL
          #{quoted_position_column} = CASE
          WHEN #{quoted_position_column} = #{current_position} THEN 1
          WHEN #{quoted_position_column} < #{current_position} THEN #{quoted_position_column} + 1
          ELSE #{quoted_position_column}
          END
        SQL

        set_position 1
        list_scope.update_all(sql) > 0
      else
        true
      end
    end
  else
    false
  end
end

#remove_from_list ⇒ Object

Removes the item from the list.



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# File 'lib/sortifiable.rb', line 353

def remove_from_list
  if in_list?
    list_class.transaction do
      ids = lock_list!
      current_position = ids.index(id) + 1

      sql = <<-SQL
        #{quoted_position_column} = CASE
        WHEN #{quoted_position_column} = #{current_position} THEN NULL
        WHEN #{quoted_position_column} > #{current_position} THEN #{quoted_position_column} - 1
        ELSE #{quoted_position_column}
        END
      SQL

      set_position nil
      list_scope.update_all(sql) > 0
    end
  else
    false
  end
end

#will_leave_list? ⇒ Boolean

Test if this record is in a scoped list but will leave the scoped list when saved

Returns:

  • (Boolean) 


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# File 'lib/sortifiable.rb', line 159

def will_leave_list?
  in_list? && scope_parts.any? { |scope_part| send("#{scope_part}_changed?") }
end