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
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()
# File lib/csv.rb, line 235 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
Public Instance Methods
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 376 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 lib/csv.rb, line 513 def ==(other) return @row == other.row if other.is_a? CSV::Row @row == other 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 343 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
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 411 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
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 428 def delete_if(&block) @row.delete_if(&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 503 def each(&block) @row.each(&block) self # for chaining 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 306 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 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 284 def field(header_or_index, minimum_index = 0) # locate the pair finder = header_or_index.is_a?(Integer) ? :[] : :assoc pair = @row[minimum_index..-1].send(finder, header_or_index) # return the field if we have a pair pair.nil? ? nil : pair.last end
Returns true
if data
matches a field in this row,
and false
otherwise.
# File lib/csv.rb, line 489 def field?(data) fields.include? data end
Returns true
if this is a field row.
# File lib/csv.rb, line 262 def field_row? not header_row? 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 442 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
Returns true
if there is a field with the given
header
.
# File lib/csv.rb, line 323 def has_key?(header) !!@row.assoc(header) end
Returns true
if name
is a header for this row,
and false
otherwise.
# File lib/csv.rb, line 480 def header?(name) headers.include? name end
Returns true
if this is a header row.
# File lib/csv.rb, line 257 def header_row? @header_row end
Returns the headers of this row.
# File lib/csv.rb, line 267 def headers @row.map { |pair| pair.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 #field.
# File lib/csv.rb, line 472 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
A summary of fields, by header, in an ASCII compatible String.
# File lib/csv.rb, line 538 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 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 395 def push(*args) args.each { |arg| self << arg } self # for chaining 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 532 def to_csv(options = Hash.new) fields.to_csv(options) end
Collapses the row into a simple Hash. Be warning that this discards field order and clobbers duplicate fields.
# File lib/csv.rb, line 522 def to_hash # flatten just one level of the internal Array Hash[*@row.inject(Array.new) { |ary, pair| ary.push(*pair) }] end