In Files

  • csv/row.rb

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

Constructs 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 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

row << [header, value] → self click to toggle source
row << hash → self
row << value → self

Adds a field to self; returns self:

If the argument is a 2-element Array [header, value], a field is added with the given header and value:

source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row << ['NAME', 'Bat']
row # => #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":"Baz" "NAME":"Bat">

If the argument is a Hash, each key-value pair is added as a field with header key and value value.

source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row << {NAME: 'Bat', name: 'Bam'}
row # => #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":"Baz" NAME:"Bat" name:"Bam">

Otherwise, the given value is added as a field with no header.

source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row << 'Bag'
row # => #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":"Baz" nil:"Bag">
 
               # File csv/row.rb, line 309
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 521
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
row[index] = value → value click to toggle source
row[header, offset] = value → value
row[header] = value → value

Assigns the field value for the given index or header; returns value.


Assign field value by Integer index:

source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
row = table[0]
row[0] = 'Bat'
row[1] = 3
row # => #<CSV::Row "Name":"Bat" "Value":3>

Counts backward from the last column if index is negative:

row[-1] = 4
row[-2] = 'Bam'
row # => #<CSV::Row "Name":"Bam" "Value":4>

Extends the row with nil:nil if positive index is not in the row:

row[4] = 5
row # => #<CSV::Row "Name":"bad" "Value":4 nil:nil nil:nil nil:5>

Raises IndexError if negative index is too small (too far from zero).


Assign field value by header (first found):

source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row['Name'] = 'Bat'
row # => #<CSV::Row "Name":"Bat" "Name":"Bar" "Name":"Baz">

Assign field value by header, ignoring offset leading fields:

source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row['Name', 2] = 4
row # => #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":4>

Append new field by (new) header:

source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
row = table[0]
row['New'] = 6
row# => #<CSV::Row "Name":"foo" "Value":"0" "New":6>
 
               # File csv/row.rb, line 259
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(index) → [header, value] or nil click to toggle source
delete(header) → [header, value] or empty_array
delete(header, offset) → [header, value] or empty_array

Removes a specified field from self; returns the 2-element Array [header, value] if the field exists.

If an Integer argument index is given, removes and returns the field at offset index, or returns nil if the field does not exist:

source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.delete(1) # => ["Name", "Bar"]
row.delete(50) # => nil

Otherwise, if the single argument header is given, removes and returns the first-found field with the given header, of returns a new empty Array if the field does not exist:

source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.delete('Name') # => ["Name", "Foo"]
row.delete('NAME') # => []

If argument header and Integer argument offset are given, removes and returns the first-found field with the given header whose index is at least as large as offset:

source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.delete('Name', 1) # => ["Name", "Bar"]
row.delete('NAME', 1) # => []
 
               # File csv/row.rb, line 371
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 {|header, value| ... } → self click to toggle source

Removes fields from self as selected by the block; returns self.

Removes each field for which the block returns a truthy value:

source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.delete_if {|header, value| value.start_with?('B') } # => true
row # => #<CSV::Row "Name":"Foo">
row.delete_if {|header, value| header.start_with?('B') } # => false

If no block is given, returns a new Enumerator:

row.delete_if # => #<Enumerator: #<CSV::Row "Name":"Foo">:delete_if>
 
               # File csv/row.rb, line 396
def delete_if(&block)
  return enum_for(__method__) { size } unless block_given?

  @row.delete_if(&block)

  self  # for chaining
end
            
dig(index_or_header, *identifiers) → object click to toggle source

Finds and returns the object in nested object that is specified by index_or_header and specifiers.

The nested objects may be instances of various classes. See Dig Methods.

Examples:

source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.dig(1) # => "0"
row.dig('Value') # => "0"
row.dig(5) # => nil
 
               # File csv/row.rb, line 581
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 507
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, default)
fetch(header) {|row| ... }

Returns the field value as specified by header.


With the single argument header, returns the field value for that header (first found):

source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.fetch('Name') # => "Foo"

Raises exception KeyError if the header does not exist.


With arguments header and default given, returns the field value for the header (first found) if the header exists, otherwise returns default:

source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.fetch('Name', '') # => "Foo"
row.fetch(:nosuch, '') # => ""

With argument header and a block given, returns the field value for the header (first found) if the header exists; otherwise calls the block and returns its return value:

source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.fetch('Name') {|header| fail 'Cannot happen' } # => "Foo"
row.fetch(:nosuch) {|header| "Header '#{header} not found'" } # => "Header 'nosuch not found'"
 
               # File csv/row.rb, line 178
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(index) click to toggle source
field(header)
field(header, offset)

Returns the field value for the given index or header.


Fetch field value by Integer index:

source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.field(0) # => "foo"
row.field(1) # => "bar"

Counts backward from the last column if index is negative:

row.field(-1) # => "0"
row.field(-2) # => "foo"

Returns nil if index is out of range:

row.field(2) # => nil
row.field(-3) # => nil

Fetch field value by header (first found):

source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.field('Name') # => "Foo"

Fetch field value by header, ignoring offset leading fields:

source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.field('Name', 2) # => "Baz"

Returns nil if the header does not exist.

 
               # File csv/row.rb, line 123
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].public_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 493
def field?(data)
  fields.include? data
end
            
field_row? → true or false click to toggle source

Returns true if this is a field row, false otherwise.

 
               # File csv/row.rb, line 68
def field_row?
  not header_row?
end
            
fields(*specifiers) click to toggle source

Returns field values per the given specifiers, which may be any mixture of:

  • Integer index.

  • Range of Integer indexes.

  • 2-element Array containing a header and offset.

  • Header.

  • Range of headers.

For specifier in one of the first four cases above, returns the result of self.field(specifier); see field.

Although there may be any number of specifiers, the examples here will illustrate one at a time.

When the specifier is an Integer index, returns self.field(index)L

source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.fields(1) # => ["Bar"]

When the specifier is a Range of Integers range, returns self.field(range):

row.fields(1..2) # => ["Bar", "Baz"]

When the specifier is a 2-element Array array, returns self.field(array)L

row.fields('Name', 1) # => ["Foo", "Bar"]

When the specifier is a header header, returns self.field(header)L

row.fields('Name') # => ["Foo"]

When the specifier is a Range of headers range, forms a new Range new_range from the indexes of range.start and range.end, and returns self.field(new_range):

source = "Name,NAME,name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.fields('Name'..'NAME') # => ["Foo", "Bar"]

Returns all fields if no argument given:

row.fields # => ["Foo", "Bar", "Baz"]
 
               # File csv/row.rb, line 450
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, false otherwise.

 
               # File csv/row.rb, line 199
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? → true or false click to toggle source

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

 
               # File csv/row.rb, line 60
def header_row?
  @header_row
end
            
headers click to toggle source

Returns the headers for this row:

source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
row = table.first
row.headers # => ["Name", "Value"]
 
               # File csv/row.rb, line 80
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 482
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_return_value = super
  @row = @row.collect(&:dup)
  super_return_value
end
            
inspect → string click to toggle source

Returns an ASCII-compatible String showing:

  • Class CSV::Row.

  • Header-value pairs.

Example:

source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.inspect # => "#<CSV::Row \"Name\":\"foo\" \"Value\":\"0\">"
 
               # File csv/row.rb, line 606
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(*values) →self click to toggle source

Appends each of the given values to self as a field; returns self:

source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.push('Bat', 'Bam')
row # => #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":"Baz" nil:"Bat" nil:"Bam">
 
               # File csv/row.rb, line 330
def push(*args)
  args.each { |arg| self << arg }

  self  # for chaining
end
            
to_csv → csv_string click to toggle source

Returns the row as a CSV String. Headers are not included:

source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.to_csv # => "foo,0\n"
 
               # File csv/row.rb, line 560
def to_csv(**options)
  fields.to_csv(**options)
end
            
Also aliased as: to_s
to_h → hash click to toggle source

Returns the new Hash formed by adding each header-value pair in self as a key-value pair in the Hash.

source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.to_h # => {"Name"=>"foo", "Value"=>"0"}

Header order is preserved, but repeated headers are ignored:

source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.to_h # => {"Name"=>"Foo"}
 
               # File csv/row.rb, line 541
def to_h
  hash = {}
  each do |key, _value|
    hash[key] = self[key] unless hash.key?(key)
  end
  hash
end
            
Also aliased as: to_hash
to_hash() click to toggle source
Alias for: to_h
to_s(**options) click to toggle source
Alias for: to_csv
values_at(*headers_and_or_indices) click to toggle source
Alias for: fields