Class: Cequel::Record::List

Inherits:
Array
  • Object
show all
Includes:
Collection
Defined in:
lib/cequel/record/collection.rb

Overview

The value of a list column in a Cequel::Record instance. List collections encapsulate and behave like the built-in ‘Array` type.

See Also:

Since:

  • 1.0.0

Constant Summary collapse

NON_ATOMIC_MUTATORS =

These methods are not available on lists because they require reading collection data before writing it.

Since:

  • 1.0.0

[
  :collect!,
  :delete_if,
  :fill,
  :flatten!,
  :insert,
  :keep_if,
  :map!,
  :pop,
  :reject!,
  :reverse!,
  :rotate!,
  :select!,
  :shift,
  :shuffle!,
  :slice!,
  :sort!,
  :sort_by!,
  :uniq!
]

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Collection

#column_name, #initialize, #inspect, #loaded!, #loaded?, #persisted!

Class Method Details

.empty ⇒ Array

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns an empty array.

Returns:

  • (Array) —

    an empty array

Since:

  • 1.0.0



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# File 'lib/cequel/record/collection.rb', line 192

def self.empty; []; end

Instance Method Details

#[]=(position, element) ⇒ void #[]=(range, elements) ⇒ void #[]=(start_position, count, elements) ⇒ void

Note:

Negative positions are not supported, as they are not allowed in CQL list operations.

This method returns an undefined value.

Set the value at a position or range of positions. This modification will be staged and persisted as an atomic list update when the record is saved. If the collection data is loaded in memory, it will also be modified accordingly.

Overloads:

  • #[]=(position, element) ⇒ void

    Parameters:

    • position (Integer) —

      position at which to set element

    • element —

      element to insert at position in list

  • #[]=(range, elements) ⇒ void

    Parameters:

    • range (Range) —

      range of positions at which to replace elements

    • elements (Array) —

      new elements to replace in this range

  • #[]=(start_position, count, elements) ⇒ void

    Parameters:

    • start_position (Integer) —

      position at which to begin replacing elements

    • count (Integer) —

      number of elements to replace

    • elements (Array) —

      new elements to replace in this range

See Also:

  • DataSet#list_replace

Since:

  • 1.0.0



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# File 'lib/cequel/record/collection.rb', line 223

def []=(position, *args)
  if position.is_a?(Range)
    first, count = position.first, position.count
  else
    first, count = position, args[-2]
  end

  element = args[-1] =
    if args[-1].is_a?(Array) then cast_collection(args[-1])
    else cast_element(args[-1])
    end

  if first < 0
    fail ArgumentError,
         "Bad index #{position}: CQL lists do not support negative " \
         "indices"
  end

  if count.nil?
    updater.list_replace(column_name, first, element)
  else
    element = Array.wrap(element)
    count.times do |i|
      if i < element.length
        updater.list_replace(column_name, first+i, element[i])
      else
        deleter.list_remove_at(column_name, first+i)
      end
    end
  end
  to_modify { super }
end

#clear ⇒ List

Remove all elements from the list. This will propagate to the database as a DELETE of the list column.

Returns:

Since:

  • 1.0.0



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# File 'lib/cequel/record/collection.rb', line 262

def clear
  deleter.delete_columns(column_name)
  to_modify { super }
end

#concat(array) ⇒ List

Concatenate another collection onto this list.

Parameters:

  • array (Array) —

    elements to concatenate

Returns:

Since:

  • 1.0.0



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# File 'lib/cequel/record/collection.rb', line 273

def concat(array)
  array = cast_collection(array)
  updater.list_append(column_name, array)
  to_modify { super }
end

#delete(object) ⇒ List

Remove all instances of a given value from the list.

Parameters:

  • object —

    value to remove

Returns:

Since:

  • 1.0.0



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# File 'lib/cequel/record/collection.rb', line 285

def delete(object)
  object = cast_element(object)
  updater.list_remove(column_name, object)
  to_modify { super }
end

#delete_at(index) ⇒ List

Remove the element at a given position from the list.

Parameters:

  • index (Integer) —

    position from which to remove the element

Returns:

Since:

  • 1.0.0



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# File 'lib/cequel/record/collection.rb', line 297

def delete_at(index)
  deleter.list_remove_at(column_name, index)
  to_modify { super }
end

#push(*objects) ⇒ List Also known as: <<, append

Push (append) one or more elements to the end of the list.

Parameters:

  • objects —

    value(s) to add to the end of the list

Returns:

Since:

  • 1.0.0



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# File 'lib/cequel/record/collection.rb', line 308

def push(*objects)
  objects.map! { |object| cast_element(object) }
  updater.list_append(column_name, objects)
  to_modify { super }
end

#replace(array) ⇒ List

Replace the entire contents of this list with a new collection

Parameters:

  • array (Array) —

    new elements for this list

Returns:

Since:

  • 1.0.0



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# File 'lib/cequel/record/collection.rb', line 322

def replace(array)
  array = cast_collection(array)
  updater.set(column_name => array)
  to_modify { super }
end

#unshift(*objects) ⇒ List Also known as: prepend

Prepend one or more values to the beginning of this list

Parameters:

  • objects —

    value(s) to add to the beginning of the list

Returns:

Since:

  • 1.0.0



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# File 'lib/cequel/record/collection.rb', line 334

def unshift(*objects)
  objects.map!(&method(:cast_element))
  updater.list_prepend(column_name, objects.reverse)
  to_modify { super }
end