CSV::Row

Internal data format used to compare equality.

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 CSV::Row.header_row?() and CSV::Row.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 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
 

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 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
 

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

 
 # File csv/row.rb, line 522
def ==(other)
 return @row == other.row if other.is_a? CSV::Row
 @row == other
end
 

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 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
 

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 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
 

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 397
def delete_if(&block)
 return enum_for(__method__) { size } unless block_given?
 @row.delete_if(&block)
 self # for chaining
end
 

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 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
 

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 508
def each(&block)
 return enum_for(__method__) { size } unless block_given?
 @row.each(&block)
 self # for chaining
end
 

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 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
 

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 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
 

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

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

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

 
 # File csv/row.rb, line 69
def field_row?
 not header_row?
end
 

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 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
 

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

 
 # File csv/row.rb, line 200
def has_key?(header)
 !!@row.assoc(header)
end
 

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

 
 # File csv/row.rb, line 61
def header_row?
 @header_row
end
 

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 81
def headers
 @row.map(&:first)
end
 

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 CSV::Row.field().

 
 # File 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
 

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 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
 

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 331
def push(*args)
 args.each { |arg| self << arg }
 self # for chaining
end
 

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 561
def to_csv(**options)
 fields.to_csv(**options)
end
 

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 542
def to_h
 hash = {}
 each do |key, _value|
 hash[key] = self[key] unless hash.key?(key)
 end
 hash
end