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Class: CSV::Row

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, Forwardable
Instance Chain:
self, Enumerable
Inherits: Object
Defined in: lib/csv/row.rb

Overview

A 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.

Class Method Summary

Instance Attribute Summary

Instance Method Summary

Constructor Details

.new(headers, fields, header_row = false) ⇒ Row

Constructs a new 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 Row.header_row?() and Row.field_row?(), that this is a header row. Otherwise, the row assumes to be a field row.

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

  • empty?()

  • length()

  • size()

[ GitHub ] 

  


# File 'lib/csv/row.rb', line 30



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


  







Instance Attribute Details



  

    #field_row?  ⇒ Boolean  (readonly)  



  

    

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


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 69



def field_row?
  not header_row?
end


  








  

    #header_row?  ⇒ Boolean  (readonly)  



  

    

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


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 61



def header_row?
  @header_row
end


  








  

    #row   (readonly, protected)
  



  

    

Internal data format used to compare equality.


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 43



attr_reader :row


  







Instance Method Details



  

    

      #row(<< [header, value])  ⇒ self 
      #<<(hash)  ⇒ self 
      #<<(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">


  





  


  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 310



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.


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 522



def ==(other)
  return @row == other.row if other.is_a? CSV::Row
  @row == other
end


  








  

    #[](header_or_index, minimum_index = 0)  
  



  

    

Alias for #field.


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 136



alias_method :[], :field


  








  

    

      #[]=(index, value)  ⇒ value 
      #[]=(header, offset, value)  ⇒ value 
      #[]=(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>


  





  


  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 260



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)  ⇒ Array, value 
      #delete(header)  ⇒ Array, value 
      #delete(header, offset)  ⇒ Array, value 
    

  



  

    

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) # => []


  





  


  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 372



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   



  

    

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>


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 397



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   



  

    

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


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 582



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)  
    Also known as: #each_pair
  



  

    

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.


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 508



def each(&block)
  return enum_for(__method__) { size } unless block_given?

  @row.each(&block)

  self  # for chaining
end


  








  

    #each_pair(&block)  
  



  

    

Alias for #each.


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 516



alias_method :each_pair, :each


  








  

    

      #fetch(header)  
      #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'"


  





  
Raises:


    
  
  • 
    (ArgumentError)
  
    • 





  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 179



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)  
      #field(header)  
      #field(header, offset)  
    

    Also known as: #[]
  



  

    

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.


  





  


  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 124



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


  








  

    #field?(data)  ⇒ Boolean 
  



  

    

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


  





  


  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 494



def field?(data)
  fields.include? data
end


  








  

    #fields(*specifiers)      Also known as: #values_at
  



  

    

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"]


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 451



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


  








  

    #has_key?(header)  ⇒ Boolean     Also known as: #include?, #key?, #member?, #header?
  



  

    

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


  





  


  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 200



def has_key?(header)
  !!@row.assoc(header)
end


  








  

    #header?(header)  
  



  

    

Alias for #has_key?.


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 206



alias_method :header?,  :has_key?


  








  

    #headers    



  

    

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"]


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 81



def headers
  @row.map(&:first)
end


  








  

    #include?(header)  
  



  

    

Alias for #has_key?.


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 203



alias_method :include?, :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 Row.field().


  





  


  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 483



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)  
  

  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 51



def initialize_copy(other)
  super_return_value = super
  @row = @row.collect(&:dup)
  super_return_value
end


  








  

    #inspect  ⇒ String   



  

    

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\">"


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 607



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?.


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 204



alias_method :key?,     :has_key?


  








  

    #member?(header)  
  



  

    

Alias for #has_key?.


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 205



alias_method :member?,  :has_key?


  








  

    #push(*values) ->self)    



  

    

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">


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 331



def push(*args)
  args.each { |arg| self << arg }

  self  # for chaining
end


  








  

    #to_ary  
  

  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 551



alias_method :to_ary, :to_a


  








  

    #to_csv  ⇒ csv_string     Also known as: #to_s
  



  

    

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"


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 561



def to_csv(**options)
  fields.to_csv(**options)
end


  








  

    #to_h  ⇒ Hash     Also known as: #to_hash
  



  

    

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"}


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 542



def to_h
  hash = {}
  each do |key, _value|
    hash[key] = self[key] unless hash.key?(key)
  end
  hash
end


  








  

    #to_hash  
  



  

    

Alias for #to_h.


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 549



alias_method :to_hash, :to_h


  








  

    #to_s(**options)  
  



  

    

Alias for #to_csv.


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 564



alias_method :to_s, :to_csv


  








  

    #values_at(*headers_and_or_indices)  
  



  

    

Alias for #fields.


  



  [ GitHub ]


  

  


# File 'lib/csv/row.rb', line 472



alias_method :values_at, :fields