Class: CSV::Row (Ruby 2.3.4)

CSV::Row

A CSV::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 CSV will be constructed from this class, if header row processing is activated.

Attributes

row[R]

Internal data format used to compare equality.

Public Class Methods

new(headers, fields, header_row = false)

Construct a new CSV::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 #header_row? and #field_row?, that this is a header row. Otherwise, the row is assumes to be a field row.

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

  • empty?()

  • length()

  • size()

 
               # File csv.rb, line 236
def initialize(headers, fields, header_row = false)
  @header_row = header_row
  headers.each { |h| h.freeze if h.is_a? String }

  # handle extra headers or fields
  @row = if headers.size >= fields.size
    headers.zip(fields)
  else
    fields.zip(headers).map { |pair| pair.reverse! }
  end
end

Public Instance Methods

<<( field )
<<( header_and_field_array )
<<( header_and_field_hash )

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 csv.rb, line 381
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]
  end

  self  # for chaining
end
==(other)

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

 
               # File csv.rb, line 518
def ==(other)
  return @row == other.row if other.is_a? CSV::Row
  @row == other
end
[](header_or_index, minimum_index = 0)
Alias for: field
[]=( header, value )
[]=( header, offset, value )
[]=( index, value )

Looks up the field by the semantics described in #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 csv.rb, line 348
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]
      @row.map! { |pair| pair.nil? ? [nil, nil] : pair }
    else                      # normal index assignment
      @row[args.first][1] = value
    end
  else
    index = index(*args)
    if index.nil?             # appending a field
      self << [args.first, value]
    else                      # normal header assignment
      @row[index][1] = value
    end
  end
end
delete( header )
delete( header, offset )
delete( index )

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

 
               # File csv.rb, line 416
def delete(header_or_index, minimum_index = 0)
  if header_or_index.is_a? Integer                 # by index
    @row.delete_at(header_or_index)
  elsif i = index(header_or_index, minimum_index)  # by header
    @row.delete_at(i)
  else
    [ ]
  end
end
delete_if(&block)

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 csv.rb, line 433
def delete_if(&block)
  @row.delete_if(&block)

  self  # for chaining
end
each(&block)

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 csv.rb, line 508
def each(&block)
  @row.each(&block)

  self  # for chaining
end
fetch( header )
fetch( header ) { |row| ... }
fetch( header, default )

This method will fetch the field value by header. It has the same behavior as Hash#fetch: if there is a field with the given header, its value is returned. Otherwise, if a block is given, it is yielded the header and its result is returned; if a default is given as the second argument, it is returned; otherwise a KeyError is raised.

 
               # File csv.rb, line 311
def fetch(header, *varargs)
  raise ArgumentError, "Too many arguments" if varargs.length > 1
  pair = @row.assoc(header)
  if pair
    pair.last
  else
    if block_given?
      yield header
    elsif varargs.empty?
      raise KeyError, "key not found: #{header}"
    else
      varargs.first
    end
  end
end
field( header )
field( header, offset )
field( index )

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

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

 
               # File csv.rb, line 285
def field(header_or_index, minimum_index = 0)
  # locate the pair
  finder = (header_or_index.is_a?(Integer) || header_or_index.is_a?(Range)) ? :[] : :assoc
  pair   = @row[minimum_index..-1].send(finder, header_or_index)

  # return the field if we have a pair
  if pair.nil?
    nil
  else
    header_or_index.is_a?(Range) ? pair.map(&:last) : pair.last
  end
end
Also aliased as: []
field?(data)

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

 
               # File csv.rb, line 494
def field?(data)
  fields.include? data
end
field_row?()

Returns true if this is a field row.

 
               # File csv.rb, line 263
def field_row?
  not header_row?
end
fields(*headers_and_or_indices)

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 #field.

If called with no arguments, all fields are returned.

 
               # File csv.rb, line 447
def fields(*headers_and_or_indices)
  if headers_and_or_indices.empty?  # return all fields--no arguments
    @row.map { |pair| pair.last }
  else                              # or work like values_at()
    headers_and_or_indices.inject(Array.new) 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(h_or_i.begin)
        index_end   = h_or_i.end.is_a?(Integer)   ? h_or_i.end :
                                                    index(h_or_i.end)
        new_range   = h_or_i.exclude_end? ? (index_begin...index_end) :
                                            (index_begin..index_end)
        fields.values_at(new_range)
      else
        [field(*Array(h_or_i))]
      end
    end
  end
end
Also aliased as: values_at
has_key?(header)

Returns true if there is a field with the given header.

 
               # File csv.rb, line 328
def has_key?(header)
  !!@row.assoc(header)
end
Also aliased as: include?, key?, member?
header?(name)

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

 
               # File csv.rb, line 485
def header?(name)
  headers.include? name
end
Also aliased as: include?
header_row?()

Returns true if this is a header row.

 
               # File csv.rb, line 258
def header_row?
  @header_row
end
headers()

Returns the headers of this row.

 
               # File csv.rb, line 268
def headers
  @row.map { |pair| pair.first }
end
include?(header)
Alias for: has_key?
index( header )
index( header, offset )

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 #field.

 
               # File csv.rb, line 477
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
end
inspect()

A summary of fields, by header, in an ASCII compatible String.

 
               # File csv.rb, line 543
def inspect
  str = ["#<", self.class.to_s]
  each do |header, field|
    str << " " << (header.is_a?(Symbol) ? header.to_s : header.inspect) <<
           ":" << field.inspect
  end
  str << ">"
  begin
    str.join('')
  rescue  # any encoding error
    str.map do |s|
      e = Encoding::Converter.asciicompat_encoding(s.encoding)
      e ? s.encode(e) : s.force_encoding("ASCII-8BIT")
    end.join('')
  end
end
key?(header)
Alias for: has_key?
member?(header)
Alias for: has_key?
push(*args)

A shortcut for appending multiple fields. Equivalent to:

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

This method returns the row for chaining.

 
               # File csv.rb, line 400
def push(*args)
  args.each { |arg| self << arg }

  self  # for chaining
end
to_csv(options = Hash.new)

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

csv_row.fields.to_csv( options )

 
               # File csv.rb, line 537
def to_csv(options = Hash.new)
  fields.to_csv(options)
end
Also aliased as: to_s
to_hash()

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

 
               # File csv.rb, line 527
def to_hash
  # flatten just one level of the internal Array
  Hash[*@row.inject(Array.new) { |ary, pair| ary.push(*pair) }]
end
to_s(options = Hash.new)
Alias for: to_csv
values_at(*headers_and_or_indices)
Alias for: fields