Liquid::For

"For" iterates over an array or collection. Several useful variables are available to you within the loop.

Basic usage:

{% for item in collection %}
  {{ forloop.index }}: {{ item.name }}
{% endfor %}

Advanced usage:

{% for item in collection %}
  <div {% if forloop.first %}class="first"{% endif %}>
    Item {{ forloop.index }}: {{ item.name }}
  </div>
{% else %}
  There is nothing in the collection.
{% endfor %}

You can also define a limit and offset much like SQL. Remember that offset starts at 0 for the first item.

  {% for item in collection limit:5 offset:10 %}
    {{ item.name }}
  {% end %}

To reverse the for loop simply use {% for item in collection reversed %}

Available variables:

forloop.name	'item-collection'
forloop.length	Length of the loop
forloop.index	The current item's position in the collection; forloop.index starts at 1. This is helpful for non-programmers who start believe the first item in an array is 1, not 0.
forloop.index0	The current item's position in the collection where the first item is 0
forloop.rindex	Number of items remaining in the loop (length - index) where 1 is the last item.
forloop.rindex0	Number of items remaining in the loop where 0 is the last item.
forloop.first	Returns true if the item is the first item.
forloop.last	Returns true if the item is the last item.

Constants

Syntax

Public Class Methods

new(tag_name, markup, tokens) click to toggle source

# File lib/liquid/tags/for.rb, line 49
def initialize(tag_name, markup, tokens)
  parse_with_selected_parser(markup)
  @nodelist = @for_block = []
  super
end

Public Instance Methods

render(context) click to toggle source

# File lib/liquid/tags/for.rb, line 60
def render(context)
  context.registers[:for] ||= Hash.new(0)

  collection = context[@collection_name]
  collection = collection.to_a if collection.is_a?(Range)

  # Maintains Ruby 1.8.7 String#each behaviour on 1.9
  return render_else(context) unless iterable?(collection)

  from = if @attributes['offset'] == 'continue'
    context.registers[:for][@name].to_i
  else
    context[@attributes['offset']].to_i
  end

  limit = context[@attributes['limit']]
  to    = limit ? limit.to_i + from : nil


  segment = Utils.slice_collection_using_each(collection, from, to)

  return render_else(context) if segment.empty?

  segment.reverse! if @reversed

  result = ''

  length = segment.length

  # Store our progress through the collection for the continue flag
  context.registers[:for][@name] = from + segment.length

  context.stack do
    segment.each_with_index do |item, index|
      context[@variable_name] = item
      context['forloop'] = {
        'name'    => @name,
        'length'  => length,
        'index'   => index + 1,
        'index0'  => index,
        'rindex'  => length - index,
        'rindex0' => length - index - 1,
        'first'   => (index == 0),
      'last'    => (index == length - 1) }

      result << render_all(@for_block, context)

      # Handle any interrupts if they exist.
      if context.has_interrupt?
        interrupt = context.pop_interrupt
        break if interrupt.is_a? BreakInterrupt
        next if interrupt.is_a? ContinueInterrupt
      end
    end
  end
  result
end

unknown_tag(tag, markup, tokens) click to toggle source

# File lib/liquid/tags/for.rb, line 55
def unknown_tag(tag, markup, tokens)
  return super unless tag == 'else'
  @nodelist = @else_block = []
end

Protected Instance Methods

lax_parse(markup) click to toggle source

# File lib/liquid/tags/for.rb, line 120
def lax_parse(markup)
  if markup =~ Syntax
    @variable_name = $1
    @collection_name = $2
    @name = "#{$1}-#{$2}"
    @reversed = $3
    @attributes = {}
    markup.scan(TagAttributes) do |key, value|
      @attributes[key] = value
    end
  else
    raise SyntaxError.new(options[:locale].t("errors.syntax.for"))
  end
end

strict_parse(markup) click to toggle source

# File lib/liquid/tags/for.rb, line 135
def strict_parse(markup)
  p = Parser.new(markup)
  @variable_name = p.consume(:id)
  raise SyntaxError.new(options[:locale].t("errors.syntax.for_invalid_in"))  unless p.id?('in')
  @collection_name = p.expression
  @name = "#{@variable_name}-#{@collection_name}"
  @reversed = p.id?('reversed')

  @attributes = {}
  while p.look(:id) && p.look(:colon, 1)
    unless attribute = p.id?('limit') || p.id?('offset')
      raise SyntaxError.new(options[:locale].t("errors.syntax.for_invalid_attribute"))
    end
    p.consume
    val = p.expression
    @attributes[attribute] = val
  end
  p.consume(:end_of_string)
end

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