Class: CSV::Row

Inherits:
Object
  • Object
show all
Extended by:
Forwardable
Includes:
Enumerable
Defined in:
lib/csv.rb

Overview

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.

Instance Method Summary collapse

Constructor Details

#initialize(headers, fields, header_row = false) ⇒ Row

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()



236
237
238
239
240
241
242
243
244
245
 
# File 'lib/csv.rb', line 236

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

Instance Method Details

#<<(arg) ⇒ Object

:call-seq:

<<( field )
<<( header_and_field_array )
<<( header_and_field_hash )

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.



340
341
342
343
344
345
346
347
348
349
350
 
# File 'lib/csv.rb', line 340

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

#==(other) ⇒ Object

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



477
478
479
 
# File 'lib/csv.rb', line 477

def ==(other)
  @row == other.row
end

#[]=(*args) ⇒ Object

:call-seq:

[]=( header, value )
[]=( header, offset, value )
[]=( index, value )

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.



307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
 
# File 'lib/csv.rb', line 307

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

#delete(header_or_index, minimum_index = 0) ⇒ Object

:call-seq:

delete( header )
delete( header, offset )
delete( index )

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.



375
376
377
378
379
380
381
382
383
 
# File 'lib/csv.rb', line 375

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

#delete_if(&block) ⇒ Object

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.



392
393
394
395
396
 
# File 'lib/csv.rb', line 392

def delete_if(&block)
  @row.delete_if(&block)

  self  # for chaining
end

#each(&block) ⇒ Object

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.



467
468
469
470
471
 
# File 'lib/csv.rb', line 467

def each(&block)
  @row.each(&block)

  self  # for chaining
end

#field(header_or_index, minimum_index = 0) ⇒ Object Also known as: []

:call-seq:

field( header )
field( header, offset )
field( index )

This method will fetch 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.



284
285
286
287
288
289
290
291
 
# 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

#field?(data) ⇒ Boolean

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

Returns:

  • (Boolean) 


453
454
455
 
# File 'lib/csv.rb', line 453

def field?(data)
  fields.include? data
end

#field_row? ⇒ Boolean

Returns true if this is a field row.

Returns:

  • (Boolean) 


262
263
264
 
# File 'lib/csv.rb', line 262

def field_row?
  not header_row?
end

#fields(*headers_and_or_indices) ⇒ Object Also known as: values_at

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.



406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
 
# File 'lib/csv.rb', line 406

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

#header?(name) ⇒ Boolean Also known as: include?

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

Returns:

  • (Boolean) 


444
445
446
 
# File 'lib/csv.rb', line 444

def header?(name)
  headers.include? name
end

#header_row? ⇒ Boolean

Returns true if this is a header row.

Returns:

  • (Boolean) 


257
258
259
 
# File 'lib/csv.rb', line 257

def header_row?
  @header_row
end

#headers ⇒ Object

Returns the headers of this row.



267
268
269
 
# File 'lib/csv.rb', line 267

def headers
  @row.map { |pair| pair.first }
end

#index(header, minimum_index = 0) ⇒ Object

:call-seq:

index( header )
index( header, offset )

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().



436
437
438
439
440
441
 
# File 'lib/csv.rb', line 436

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

#inspect ⇒ Object

A summary of fields, by header, in an ASCII compatible String.



501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
 
# File 'lib/csv.rb', line 501

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

#push(*args) ⇒ Object

A shortcut for appending multiple fields. Equivalent to:

args.each { |arg| csv_row << arg }

This method returns the row for chaining.



359
360
361
362
363
 
# File 'lib/csv.rb', line 359

def push(*args)
  args.each { |arg| self << arg }

  self  # for chaining
end

#to_csv(options = Hash.new) ⇒ Object Also known as: to_s

Returns the row as a CSV String. Headers are not used. Equivalent to:

csv_row.fields.to_csv( options )



495
496
497
 
# File 'lib/csv.rb', line 495

def to_csv(options = Hash.new)
  fields.to_csv(options)
end

#to_hash ⇒ Object

Collapses the row into a simple Hash. Be warning that this discards field order and clobbers duplicate fields.



485
486
487
488
 
# File 'lib/csv.rb', line 485

def to_hash
  # flatten just one level of the internal Array
  Hash[*@row.inject(Array.new) { |ary, pair| ary.push(*pair) }]
end