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) click to toggle source

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/row.rb, line 29
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).each(&:reverse!)
  end
end

Public Instance Methods

<<( field ) click to toggle source

<<( 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/row.rb, line 180
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) click to toggle source

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

 
               # File csv/row.rb, line 321
def ==(other)
  return @row == other.row if other.is_a? CSV::Row
  @row == other
end

[](header_or_index, minimum_index = 0) click to toggle source

Alias for: field

[]=( header, value ) click to toggle source

[]=( 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/row.rb, line 147
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 ) click to toggle source

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/row.rb, line 215
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) click to toggle source

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.

If no block is given, an Enumerator is returned.

 
               # File csv/row.rb, line 234
def delete_if(&block)
  return enum_for(__method__) { size } unless block_given?

  @row.delete_if(&block)

  self  # for chaining
end

dig(index_or_header, *indexes) click to toggle source

Extracts the nested value specified by the sequence of index or header objects by calling dig at each step, returning nil if any intermediate step is nil.

 
               # File csv/row.rb, line 355
def dig(index_or_header, *indexes)
  value = field(index_or_header)
  if value.nil?
    nil
  elsif indexes.empty?
    value
  else
    unless value.respond_to?(:dig)
      raise TypeError, "#{value.class} does not have \#dig method"
    end
    value.dig(*indexes)
  end
end

each(&block) click to toggle source

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

If no block is given, an Enumerator is returned.

Support for Enumerable.

 
               # File csv/row.rb, line 307
def each(&block)
  return enum_for(__method__) { size } unless block_given?

  @row.each(&block)

  self  # for chaining
end

Also aliased as: each_pair

each_pair(&block) click to toggle source

Alias for: each

fetch( header ) click to toggle source

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/row.rb, line 109
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 ) click to toggle source

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/row.rb, line 83
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) click to toggle source

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

 
               # File csv/row.rb, line 293
def field?(data)
  fields.include? data
end

field_row?() click to toggle source

Returns true if this is a field row.

 
               # File csv/row.rb, line 61
def field_row?
  not header_row?
end

fields(*headers_and_or_indices) click to toggle source

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/row.rb, line 250
def fields(*headers_and_or_indices)
  if headers_and_or_indices.empty?  # return all fields--no arguments
    @row.map(&:last)
  else                              # or work like values_at()
    all = []
    headers_and_or_indices.each do |h_or_i|
      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)
        all.concat(fields.values_at(new_range))
      else
        all << field(*Array(h_or_i))
      end
    end
    return all
  end
end

Also aliased as: values_at

has_key?(header) click to toggle source

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

 
               # File csv/row.rb, line 126
def has_key?(header)
  !!@row.assoc(header)
end

Also aliased as: include?, key?, member?, header?

header?(header) click to toggle source

Alias for: has_key?

header_row?() click to toggle source

Returns true if this is a header row.

 
               # File csv/row.rb, line 56
def header_row?
  @header_row
end

headers() click to toggle source

Returns the headers of this row.

 
               # File csv/row.rb, line 66
def headers
  @row.map(&:first)
end

include?(header) click to toggle source

Alias for: has_key?

index( header ) click to toggle source

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/row.rb, line 282
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

initialize_copy(other) click to toggle source

 
               # File csv/row.rb, line 50
def initialize_copy(other)
  super
  @row = @row.dup
end

inspect() click to toggle source

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

 
               # File csv/row.rb, line 370
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) click to toggle source

Alias for: has_key?

member?(header) click to toggle source

Alias for: has_key?

push(*args) click to toggle source

A shortcut for appending multiple fields. Equivalent to:

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

This method returns the row for chaining.

 
               # File csv/row.rb, line 199
def push(*args)
  args.each { |arg| self << arg }

  self  # for chaining
end

to_csv(**options) click to toggle source

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

csv_row.fields.to_csv( options )

 
               # File csv/row.rb, line 346
def to_csv(**options)
  fields.to_csv(options)
end

Also aliased as: to_s

to_h() click to toggle source

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

 
               # File csv/row.rb, line 330
def to_h
  hash = {}
  each do |key, _value|
    hash[key] = self[key] unless hash.key?(key)
  end
  hash
end

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