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.
Internal data format used to compare equality.
# File tmp/rubies/ruby-2.5.9/lib/csv.rb, line 237
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
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 CSV::Row.header_row?() and CSV::Row.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 tmp/rubies/ruby-2.5.9/lib/csv.rb, line 382
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
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 tmp/rubies/ruby-2.5.9/lib/csv.rb, line 527
def ==(other)
return @row == other.row if other.is_a? CSV::Row
@row == other
end
Returns true if this row contains the same headers and fields in the same order as other.
# File tmp/rubies/ruby-2.5.9/lib/csv.rb, line 349
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
Looks up the field by the semantics described in CSV::Row.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 tmp/rubies/ruby-2.5.9/lib/csv.rb, line 417
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
Used to remove a pair from the row by header or index. The pair is located as described in CSV::Row.field(). The deleted pair is returned, or nil if a pair could not be found.
# File tmp/rubies/ruby-2.5.9/lib/csv.rb, line 436
def delete_if(&block)
block or return enum_for(__method__) { size }
@row.delete_if(&block)
self # for chaining
end
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 tmp/rubies/ruby-2.5.9/lib/csv.rb, line 515
def each(&block)
block or return enum_for(__method__) { size }
@row.each(&block)
self # for chaining
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 tmp/rubies/ruby-2.5.9/lib/csv.rb, line 312
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
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 tmp/rubies/ruby-2.5.9/lib/csv.rb, line 286
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
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 tmp/rubies/ruby-2.5.9/lib/csv.rb, line 501
def field?(data)
fields.include? data
end
Returns true if data matches a field in this row, and false otherwise.
# File tmp/rubies/ruby-2.5.9/lib/csv.rb, line 264
def field_row?
not header_row?
end
Returns true if this is a field row.
# File tmp/rubies/ruby-2.5.9/lib/csv.rb, line 452
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
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 CSV::Row.field().
If called with no arguments, all fields are returned.
# File tmp/rubies/ruby-2.5.9/lib/csv.rb, line 329
def has_key?(header)
!!@row.assoc(header)
end
Returns true if there is a field with the given header.
# File tmp/rubies/ruby-2.5.9/lib/csv.rb, line 492
def header?(name)
headers.include? name
end
Returns true if name is a header for this row, and false otherwise.
# File tmp/rubies/ruby-2.5.9/lib/csv.rb, line 259
def header_row?
@header_row
end
Returns true if this is a header row.
# File tmp/rubies/ruby-2.5.9/lib/csv.rb, line 269
def headers
@row.map(&:first)
end
Returns the headers of this row.
# File tmp/rubies/ruby-2.5.9/lib/csv.rb, line 484
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
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 tmp/rubies/ruby-2.5.9/lib/csv.rb, line 551
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
A summary of fields, by header, in an ASCII compatible String.
# File tmp/rubies/ruby-2.5.9/lib/csv.rb, line 401
def push(*args)
args.each { |arg| self << arg }
self # for chaining
end
A shortcut for appending multiple fields. Equivalent to:
args.each { |arg| csv_row << arg }
This method returns the row for chaining.
# File tmp/rubies/ruby-2.5.9/lib/csv.rb, line 545
def to_csv(**options)
fields.to_csv(options)
end
Returns the row as a CSV String. Headers are not used. Equivalent to:
csv_row.fields.to_csv( options )
# File tmp/rubies/ruby-2.5.9/lib/csv.rb, line 536
def to_hash
@row.to_h
end
Collapses the row into a simple Hash. Be warned that this discards field order and clobbers duplicate fields.