class 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
Internal data format used to compare equality.
Public Class Methods
# File lib/csv.rb, line 236
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).map { |pair| pair.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 #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()
Public Instance Methods
# File lib/csv.rb, line 381
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 lib/csv.rb, line 518 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 lib/csv.rb, line 348
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 #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 lib/csv.rb, line 416
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 #field. The deleted pair is returned, or nil if a pair could not be found.
# File lib/csv.rb, line 433 def delete_if(&block) @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.
# File lib/csv.rb, line 508 def each(&block) @row.each(&block) self # for chaining end
Yields each pair of the row as header and field tuples (much like iterating over a Hash).
Support for Enumerable.
This method returns the row for chaining.
# File lib/csv.rb, line 311
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 lib/csv.rb, line 285
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 lib/csv.rb, line 494 def field?(data) fields.include? data end
Returns true if data matches a field in this row, and false otherwise.
# File lib/csv.rb, line 263 def field_row? not header_row? end
Returns true if this is a field row.
# File lib/csv.rb, line 447
def fields(*headers_and_or_indices)
if headers_and_or_indices.empty? # return all fields--no arguments
@row.map { |pair| pair.last }
else # or work like values_at()
headers_and_or_indices.inject(Array.new) do |all, h_or_i|
all + 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)
fields.values_at(new_range)
else
[field(*Array(h_or_i))]
end
end
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 #field.
If called with no arguments, all fields are returned.
# File lib/csv.rb, line 328 def has_key?(header) [email protected](header) end
Returns true if there is a field with the given header.
# File lib/csv.rb, line 485 def header?(name) headers.include? name end
Returns true if name is a header for this row, and false otherwise.
# File lib/csv.rb, line 258 def header_row? @header_row end
Returns true if this is a header row.
# File lib/csv.rb, line 268
def headers
@row.map { |pair| pair.first }
end Returns the headers of this row.
# File lib/csv.rb, line 477 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 #field.
# File lib/csv.rb, line 543
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 lib/csv.rb, line 400
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 lib/csv.rb, line 537 def to_csv(options = Hash.new) 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 lib/csv.rb, line 527
def to_hash
# flatten just one level of the internal Array
Hash[*@row.inject(Array.new) { |ary, pair| ary.push(*pair) }]
end Collapses the row into a simple Hash. Be warned that this discards field order and clobbers duplicate fields.
Ruby Core © 1993–2017 Yukihiro Matsumoto
Licensed under the Ruby License.
Ruby Standard Library © contributors
Licensed under their own licenses.