In Files
- csv.rb
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Methods
Included Modules
- Enumerable
Class/Module Index
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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.
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 csv.rb, line 235
def initialize(headers, fields, header_row = false)
@header_row = header_row
# 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 csv.rb, line 375
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.rb, line 512
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 csv.rb, line 342
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 csv.rb, line 410
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 csv.rb, line 427
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 csv.rb, line 502
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 csv.rb, line 305
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 occurrs on
or later than the offset index. You can use this to find
duplicate headers, without resorting to hard-coding exact indices.
# File csv.rb, line 283
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 csv.rb, line 488
def field?(data)
fields.include? data
end
Returns true if this is a field row.
# File csv.rb, line 261
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 csv.rb, line 441
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 csv.rb, line 322
def has_key?(header)
!!@row.assoc(header)
end
Returns true if name is a header for this row,
and false otherwise.
# File csv.rb, line 479
def header?(name)
headers.include? name
end
Returns true if this is a header row.
# File csv.rb, line 256
def header_row?
@header_row
end
Returns the headers of this row.
# File csv.rb, line 266
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 csv.rb, line 471
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 csv.rb, line 537
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 csv.rb, line 394
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 csv.rb, line 531
def to_csv(options = Hash.new)
fields.to_csv(options)
end