Class FasterCSV::Row
In: lib/faster_csv.rb
Parent: Object

A FasterCSV::Row is part Array and part Hash. It retains an order for the fields and allows duplicates just as an Array would, but also allows you to access fields by name just as you could if they were in a Hash.

All rows returned by FasterCSV will be constructed from this class, if header row processing is activated.


<<   ==   []   []=   delete   delete_if   each   field   field?   field_row?   fields   header?   header_row?   headers   include?   index   inspect   new   push   to_csv   to_hash   to_s   values_at  

Included Modules



row  [R]  Internal data format used to compare equality.

Public Class methods

Construct a new FasterCSV::Row from headers and fields, which are expected to be Arrays. If one Array is shorter than the other, it will be padded with nil objects.

The optional header_row parameter can be set to true to indicate, via FasterCSV::Row.header_row?() and FasterCSV::Row.field_row?(), that this is a header row. Otherwise, the row is assumes to be a field row.

A FasterCSV::Row object supports the following Array methods through delegation:

  • empty?()
  • length()
  • size()


# File lib/faster_csv.rb, line 130
      def initialize(headers, fields, header_row = false)
        @header_row = header_row

        # handle extra headers or fields
        @row = if headers.size > fields.size

 { |pair| pair.reverse }

Public Instance methods

If a two-element Array is provided, it is assumed to be a header and field and the pair is appended. A Hash works the same way with the key being the header and the value being the field. Anything else is assumed to be a lone field which is appended with a nil header.

This method returns the row for chaining.


# File lib/faster_csv.rb, line 234
      def <<(arg)
        if arg.is_a?(Array) and arg.size == 2  # appending a header and name
          @row << arg
        elsif arg.is_a?(Hash)                  # append header and name pairs
          arg.each { |pair| @row << pair }
        else                                   # append field value
          @row << [nil, arg]

        self  # for chaining

Returns true if this row contains the same headers and fields in the same order as other.


# File lib/faster_csv.rb, line 371
      def ==(other)
        @row == other.row
[](header_or_index, minimum_index = 0)

Alias for field

Looks up the field by the semantics described in FasterCSV::Row.field() and assigns the value.

Assigning past the end of the row with an index will set all pairs between to [nil, nil]. Assigning to an unused header appends the new pair.


# File lib/faster_csv.rb, line 201
      def []=(*args)
        value = args.pop

        if args.first.is_a? Integer
          if @row[args.first].nil?  # extending past the end with index
            @row[args.first] = [nil, value]
  ! { |pair| pair.nil? ? [nil, nil] : pair }
          else                      # normal index assignment
            @row[args.first][1] = value
          index = index(*args)
          if index.nil?             # appending a field
            self << [args.first, value]
          else                      # normal header assignment
            @row[index][1] = value

Used to remove a pair from the row by header or index. The pair is located as described in FasterCSV::Row.field(). The deleted pair is returned, or nil if a pair could not be found.


# File lib/faster_csv.rb, line 269
      def delete(header_or_index, minimum_index = 0)
        if header_or_index.is_a? Integer                 # by index
        elsif i = index(header_or_index, minimum_index)  # by header
          [ ]

The provided block is passed a header and field for each pair in the row and expected to return true or false, depending on whether the pair should be deleted.

This method returns the row for chaining.


# File lib/faster_csv.rb, line 286
      def delete_if(&block)

        self  # for chaining

Yields each pair of the row as header and field tuples (much like iterating over a Hash).

Support for Enumerable.

This method returns the row for chaining.


# File lib/faster_csv.rb, line 361
      def each(&block)

        self  # for chaining

This method will fetch the field value by header or index. If a field is not found, nil is returned.

When provided, offset ensures that a header match occurrs on or later than the offset index. You can use this to find duplicate headers, without resorting to hard-coding exact indices.


# File lib/faster_csv.rb, line 178
      def field(header_or_index, minimum_index = 0)
        # locate the pair
        finder = header_or_index.is_a?(Integer) ? :[] : :assoc
        pair   = @row[minimum_index..-1].send(finder, header_or_index)

        # return the field if we have a pair
        pair.nil? ? nil : pair.last

Returns true if data matches a field in this row, and false otherwise.


# File lib/faster_csv.rb, line 347
      def field?(data)
        fields.include? data

Returns true if this is a field row.


# File lib/faster_csv.rb, line 156
      def field_row?
        not header_row?

This method accepts any number of arguments which can be headers, indices, Ranges of either, or two-element Arrays containing a header and offset. Each argument will be replaced with a field lookup as described in FasterCSV::Row.field().

If called with no arguments, all fields are returned.


# File lib/faster_csv.rb, line 300
      def fields(*headers_and_or_indices)
        if headers_and_or_indices.empty?  # return all fields--no arguments
 { |pair| pair.last }
        else                              # or work like values_at()
          headers_and_or_indices.inject( do |all, h_or_i|
            all + if h_or_i.is_a? Range
              index_begin = h_or_i.begin.is_a?(Integer) ? h_or_i.begin :
              index_end   = h_or_i.end.is_a?(Integer)   ? h_or_i.end :
              new_range   = h_or_i.exclude_end? ? (index_begin...index_end) :

Returns true if name is a header for this row, and false otherwise.


# File lib/faster_csv.rb, line 338
      def header?(name)
        headers.include? name

Returns true if this is a header row.


# File lib/faster_csv.rb, line 151
      def header_row?

Returns the headers of this row.


# File lib/faster_csv.rb, line 161
      def headers { |pair| pair.first }

Alias for header?

This method will return the index of a field with the provided header. The offset can be used to locate duplicate header names, as described in FasterCSV::Row.field().


# File lib/faster_csv.rb, line 330
      def index(header, minimum_index = 0)
        # find the pair
        index = headers[minimum_index..-1].index(header)
        # return the index at the right offset, if we found one
        index.nil? ? nil : index + minimum_index

A summary of fields, by header.


# File lib/faster_csv.rb, line 395
      def inspect
        str = "#<#{self.class}"
        each do |header, field|
          str << " #{header.is_a?(Symbol) ? header.to_s : header.inspect}:" <<
        str << ">"

A shortcut for appending multiple fields. Equivalent to:

  args.each { |arg| faster_csv_row << arg }

This method returns the row for chaining.


# File lib/faster_csv.rb, line 253
      def push(*args)
        args.each { |arg| self << arg }

        self  # for chaining

Returns the row as a CSV String. Headers are not used. Equivalent to:

  faster_csv_row.fields.to_csv( options )


# File lib/faster_csv.rb, line 389
      def to_csv(options =

Collapses the row into a simple Hash. Be warning that this discards field order and clobbers duplicate fields.


# File lib/faster_csv.rb, line 379
      def to_hash
        # flatten just one level of the internal Array
        Hash[*@row.inject( { |ary, pair| ary.push(*pair) }]
to_s(options =

Alias for to_csv


Alias for fields