Class: CSV
| Relationships & Source Files | |
| Namespace Children | |
| Classes: | |
| Exceptions: | |
| Super Chains via Extension / Inclusion / Inheritance | |
| Class Chain: 
          self,
          Forwardable
         | |
| Instance Chain: 
          self,
          Enumerable
         | |
| Inherits: | Object | 
| Defined in: | lib/csv.rb | 
Overview
This class provides a complete interface to CSV files and data.  It offers tools to enable you to read and write to and from Strings or IO objects, as needed.
Reading
From a File
A Line at a Time
CSV.foreach("path/to/file.csv") do |row|
  # use row here...
endAll at Once
arr_of_arrs = CSV.read("path/to/file.csv")From a String
A Line at a Time
CSV.parse("CSV,data,String") do |row|
  # use row here...
endAll at Once
arr_of_arrs = CSV.parse("CSV,data,String")Writing
To a File
CSV.open("path/to/file.csv", "wb") do |csv|
  csv << ["row", "of", "CSV", "data"]
  csv << ["another", "row"]
  # ...
endTo a String
csv_string = CSV.generate do |csv|
  csv << ["row", "of", "CSV", "data"]
  csv << ["another", "row"]
  # ...
endConvert a Single Line
csv_string = ["CSV", "data"].to_csv   # to CSV
csv_array  = "CSV,String".parse_csv   # from CSVShortcut Interface
CSV             { |csv_out| csv_out << %w{my data here} }  # to $stdout
CSV(csv = "")   { |csv_str| csv_str << %w{my data here} }  # to a String
CSV($stderr)    { |csv_err| csv_err << %w{my data here} }  # to $stderr
CSV($stdin)     { |csv_in|  csv_in.each { |row| p row } }  # from $stdinAdvanced Usage
Wrap an IO Object
csv = CSV.new(io, )
# ... read (with gets() or each()) from and write (with <<) to csv here ...CSV and Character Encodings (M17n or Multilingualization)
This new CSV parser is m17n savvy.  The parser works in the Encoding of the IO or ::String object being read from or written to.  Your data is never transcoded (unless you ask Ruby to transcode it for you) and will literally be parsed in the Encoding it is in.  Thus CSV will return Arrays or Rows of Strings in the Encoding of your data.  This is accomplished by transcoding the parser itself into your Encoding.
Some transcoding must take place, of course, to accomplish this multiencoding support.  For example, :col_sep, :row_sep, and :quote_char must be transcoded to match your data.  Hopefully this makes the entire process feel transparent, since CSV's defaults should just magically work for your data.  However, you can set these values manually in the target Encoding to avoid the translation.
It's also important to note that while all of CSV's core parser is now Encoding agnostic, some features are not. For example, the built-in converters will try to transcode data to UTF-8 before making conversions. Again, you can provide custom converters that are aware of your Encodings to avoid this translation. It's just too hard for me to support native conversions in all of Ruby's Encodings.
Anyway, the practical side of this is simple:  make sure IO and ::String objects passed into CSV have the proper Encoding set and everything should just work. CSV methods that allow you to open IO objects (CSV::foreach(), CSV::open(), CSV::read(), and CSV::readlines()) do allow you to specify the Encoding.
One minor exception comes when generating CSV into a ::String with an Encoding that is not ASCII compatible.  There's no existing data for CSV to use to prepare itself and thus you will probably need to manually specify the desired Encoding for most of those cases.  It will try to guess using the fields in a row of output though, when using CSV::generate_line() or Array#to_csv().
I try to point out any other Encoding issues in the documentation of methods as they come up.
This has been tested to the best of my ability with all non-“dummy” Encodings Ruby ships with. However, it is brave new code and may have some bugs. Please feel free to report any issues you find with it.
Constant Summary
- 
    ConverterEncoding =
    # File 'lib/csv.rb', line 940The encoding used by all converters. Encoding.find("UTF-8") 
- 
    Converters =
    # File 'lib/csv.rb', line 966This Hash holds the built-in converters of CSVthat can be accessed by name. You can selectConverterswithCSV.convert() or through theoptionsHash passed to CSV::new().- :integer
- 
Converts any field Integer() accepts. 
- :float
- 
Converts any field Float() accepts. 
- :numeric
- 
A combination of :integerand:float.
- :date
- 
Converts any field Date::parse() accepts. 
- :date_time
- 
Converts any field DateTime::parse() accepts. 
- :all
- 
All built-in converters. A combination of :date_timeand:numeric.
 All built-in converters transcode field data to UTF-8 before attempting a conversion. If your data cannot be transcoded to UTF-8 the conversion will fail and the field will remain unchanged. This Hash is intentionally left unfrozen and users should feel free to add values to it that can be accessed by all CSVobjects.To add a combo field, the value should be an ::Array of names. Combo fields can be nested with other combo fields. { integer: lambda { |f| Integer(f.encode(ConverterEncoding)) rescue f }, float: lambda { |f| Float(f.encode(ConverterEncoding)) rescue f }, numeric: [:integer, :float], date: lambda { |f| begin e = f.encode(ConverterEncoding) e =~ DateMatcher ? Date.parse(e) : f rescue # encoding conversion or date parse errors f end }, date_time: lambda { |f| begin e = f.encode(ConverterEncoding) e =~ DateTimeMatcher ? DateTime.parse(e) : f rescue # encoding conversion or date parse errors f end }, all: [:date_time, :numeric], }
- 
    DEFAULT_OPTIONS =
    # File 'lib/csv.rb', line 1039The options used when no overrides are given by calling code. They are: - :col_sep
- 
","
- :row_sep
- 
:auto
- :quote_char
- 
'"'
- :field_size_limit
- 
nil
- :converters
- 
nil
- :unconverted_fields
- 
nil
- :headers
- 
false
- :return_headers
- 
false
- :header_converters
- 
nil
- :skip_blanks
- 
false
- :force_quotes
- 
false
- :skip_lines
- 
nil
- :liberal_parsing
- 
false
 { col_sep: ",", row_sep: :auto, quote_char: '"', field_size_limit: nil, converters: nil, unconverted_fields: nil, headers: false, return_headers: false, header_converters: nil, skip_blanks: false, force_quotes: false, skip_lines: nil, liberal_parsing: false, }.freeze
- 
    DateMatcher =
    # File 'lib/csv.rb', line 932A Regexp used to find and convert some common Date formats. / \A(?: (\w,?\s)?\w\s\d{1,2},?\s+\d{2,4} | \d{4}-\d{2}-\d{2} )\z /x
- 
    DateTimeMatcher =
    # File 'lib/csv.rb', line 935A Regexp used to find and convert some common DateTime formats. / \A(?: (\w,?\s)?\w\s\d{1,2}\s\d{1,2}:\d{1,2}:\d{1,2},?\s\d{2,4} | \d{4}-\d{2}-\d{2}\s\d{2}:\d{2}:\d{2} )\z /x
- 
    HeaderConverters =
    # File 'lib/csv.rb', line 1014This Hash holds the built-in header converters of CSVthat can be accessed by name. You can selectHeaderConverterswithCSV.header_convert() or through theoptionsHash passed to CSV::new().- :downcase
- 
Calls downcase() on the header ::String. 
- :symbol
- 
Leading/trailing spaces are dropped, string is downcased, remaining spaces are replaced with underscores, non-word characters are dropped, and finally to_sym() is called. 
 All built-in header converters transcode header data to UTF-8 before attempting a conversion. If your data cannot be transcoded to UTF-8 the conversion will fail and the header will remain unchanged. This Hash is intentionally left unfrozen and users should feel free to add values to it that can be accessed by all CSVobjects.To add a combo field, the value should be an ::Array of names. Combo fields can be nested with other combo fields. { downcase: lambda { |h| h.encode(ConverterEncoding).downcase }, symbol: lambda { |h| h.encode(ConverterEncoding).downcase.strip.gsub(/\s+/, "_"). gsub(/\W+/, "").to_sym } }
- 
    VERSION =
    # File 'lib/csv.rb', line 211The version of the installed library. "2.4.8"
Class Method Summary
- 
    
      .filter(options = Hash.new) {|row| ... } 
    
    This method is a convenience for building Unix-like filters for CSVdata.
- 
    
      .foreach(path, options = Hash.new, &block)  
    
    This method is intended as the primary interface for reading CSVfiles.
- .generate(str, options = Hash.new) {|csv| ... }
- 
    
      .generate_line(row, options = Hash.new)  
    
    This method is a shortcut for converting a single row (Array) into a CSVString.
- 
    
      .instance(data = $stdout, options = Hash.new)  
    
    This method will return a CSVinstance, just like CSV::new(), but the instance will be cached and returned for all future calls to this method for the samedataobject (tested by Object#object_id()) with the sameoptions.
- 
    
      .new(data, options = Hash.new)  ⇒ CSV 
    
    constructor
    This constructor will wrap either a ::String or IO object passed in datafor reading and/or writing.
- 
    
      .open(filename, mode = "rb", options = Hash.new) {|faster_csv| ... } 
    
    This method opens an IO object, and wraps that with CSV.
- 
    
      .parse(str, options = Hash.new) {|row| ... } 
    
    This method can be used to easily parse CSVout of a ::String.
- 
    
      .parse_line(line, options = Hash.new)  
    
    This method is a shortcut for converting a single line of a CSVString into an ::Array.
- 
    
      .read(path, *options)  
    
    Use to slurp a CSVfile into an ::Array of Arrays.
- 
    
      .readlines(*args)  
    
    Alias for CSV::read(). 
- 
    
      .table(path, options = Hash.new)  
    
    A shortcut for: 
Instance Attribute Summary
- 
    
      #col_sep  
    
    readonly
    The encoded :col_sepused in parsing and writing.
- 
    
      #encoding  
    
    readonly
    The Encoding CSVis parsing or writing in.
- 
    
      #field_size_limit  
    
    readonly
    The limit for field size, if any. 
- 
    
      #header_row?  ⇒ Boolean 
    
    readonly
    Returns trueif the next row read will be a header row.
- 
    
      #lineno  
    
    readonly
    The line number of the last row read from this file. 
- 
    
      #quote_char  
    
    readonly
    The encoded :quote_charused in parsing and writing.
- 
    
      #row_sep  
    
    readonly
    The encoded :row_sepused in parsing and writing.
- 
    
      #skip_lines  
    
    readonly
    The regex marking a line as a comment. 
Instance Method Summary
- #<<(row) (also: #add_row, #puts)
- 
    
      #add_row(row)  
    
    Alias for #<<. 
- 
    
      #convert(name)  
    
    You can use this method to install a Converters built-in, or provide a block that handles a custom conversion. 
- 
    
      #converters  
    
    Returns the current list of converters in effect. 
- 
    
      #each  
    
    Yields each row of the data source in turn. 
- 
    
      #force_quotes?  ⇒ Boolean 
    
    Returns trueif all output fields are quoted.
- 
    
      #gets  
    
    Alias for #shift. 
- 
    
      #header_convert(name)  
    
    Identical to CSV#convert(), but for header rows. 
- 
    
      #header_converters  
    
    Returns the current list of converters in effect for headers. 
- 
    
      #headers  
    
    Returns nilif headers will not be used,trueif they will but have not yet been read, or the actual headers after they have been read.
- 
    
      #inspect  
    
    Returns a simplified description of the key CSVattributes in an ASCII compatible ::String.
- 
    
      #liberal_parsing?  ⇒ Boolean 
    
    Returns trueif illegal input is handled.
- 
    
      #puts(row)  
    
    Alias for #<<. 
- 
    
      #read  
      (also: #readlines)
    
    Slurps the remaining rows and returns an ::Array of Arrays. 
- 
    
      #readline  
    
    Alias for #shift. 
- 
    
      #readlines  
    
    Alias for #read. 
- 
    
      #return_headers?  ⇒ Boolean 
    
    Returns trueif headers will be returned as a row of results.
- 
    
      #rewind  
    
    Rewinds the underlying IO object and resets CSV's lineno() counter. 
- #shift (also: #gets, #readline)
- 
    
      #skip_blanks?  ⇒ Boolean 
    
    Returns trueblank lines are skipped by the parser.
- 
    
      #unconverted_fields?  ⇒ Boolean 
    
    Returns trueif unconverted_fields() to parsed results.
- 
    
      #write_headers?  ⇒ Boolean 
    
    Returns trueif headers are written in output.
- 
    
      #add_converter(var_name, const, name = nil, &converter)  
    
    private
    The actual work method for adding converters, used by both CSV.convert() andCSV.header_convert().
- 
    
      #add_unconverted_fields(row, fields)  
    
    private
    This method injects an instance variable unconverted_fieldsintorowand an accessor method forrowcalled unconverted_fields().
- 
    
      #convert_fields(fields, headers = false)  
    
    private
    Processes fieldswith@converters, or@header_convertersif #headers is passed astrue, returning the converted field set.
- 
    
      #encode_re(*chunks)  
    
    private
    Builds a regular expression in @encoding.
- 
    
      #encode_str(*chunks)  
    
    private
    Builds a ::String in @encoding.
- 
    
      #escape_re(str)  
    
    private
    This method is an encoding safe version of Regexp::escape(). 
- 
    
      #init_comments(options)  
    
    private
    Stores the pattern of comments to skip from the provided options. 
- 
    
      #init_converters(options, field_name = :converters)  
    
    private
    Loads any converters requested during construction. 
- 
    
      #init_headers(options)  
    
    private
    Stores header row settings and loads header converters, if needed. 
- 
    
      #init_parsers(options)  
    
    private
    Pre-compiles parsers and stores them by name for access during reads. 
- 
    
      #init_separators(options)  
    
    private
    Stores the indicated separators for later use. 
- 
    
      #parse_headers(row = nil)  
    
    private
    This method is used to turn a finished rowinto a Row.
- 
    
      #raw_encoding(default = Encoding::ASCII_8BIT)  
    
    private
    Returns the encoding of the internal IO object or the defaultif the encoding cannot be determined.
Constructor Details
    .new(data, options = Hash.new)  ⇒ CSV 
  
This constructor will wrap either a ::String or IO object passed in data for reading and/or writing.  In addition to the CSV instance methods, several IO methods are delegated.  (See CSV::open() for a complete list.)  If you pass a ::String for data, you can later retrieve it (after writing to it, for example) with CSV.string().
Note that a wrapped ::String will be positioned at the beginning (for reading). If you want it at the end (for writing), use CSV::generate(). If you want any other positioning, pass a preset StringIO object instead.
You may set any reading and/or writing preferences in the options Hash. Available options are:
- :col_sep
- 
The String placed between each field. This String will be transcoded into the data's Encoding before parsing. 
- :row_sep
- 
The String appended to the end of each row. This can be set to the special :autosetting, which requests that CSV automatically discover this from the data. Auto-discovery reads ahead in the data looking for the next"\r\n","\n", or"\r"sequence. A sequence will be selected even if it occurs in a quoted field, assuming that you would have the same line endings there. If none of those sequences is found,dataisARGF,STDIN,STDOUT, orSTDERR, or the stream is only available for output, the default$INPUT_RECORD_SEPARATOR($/) is used. Obviously, discovery takes a little time. Set manually if speed is important. Also note that IO objects should be opened in binary mode on Windows if this feature will be used as the line-ending translation can cause problems with resetting the document position to where it was before the read ahead. This String will be transcoded into the data's Encoding before parsing.
- :quote_char
- 
The character used to quote fields. This has to be a single character String. This is useful for application that incorrectly use 'as the quote character instead of the correct". CSV will always consider a double sequence of this character to be an escaped quote. This String will be transcoded into the data's Encoding before parsing.
- :field_size_limit
- 
This is a maximum size CSVwill read ahead looking for the closing quote for a field. (In truth, it reads to the first line ending beyond this size.) If a quote cannot be found within the limit CSV will raise a MalformedCSVError, assuming the data is faulty. You can use this limit to prevent what are effectively DoS attacks on the parser. However, this limit can cause a legitimate parse to fail and thus is set tonil, or off, by default.
- :converters
- 
An Array of names from the Converters Hash and/or lambdas that handle custom conversion. A single converter doesn't have to be in an Array. All built-in converters try to transcode fields to UTF-8 before converting. The conversion will fail if the data cannot be transcoded, leaving the field unchanged. 
- :unconverted_fields
- 
If set to true, an unconverted_fields() method will be added to all returned rows (Array or CSV::Row) that will return the fields as they were before conversion. Note that:headerssupplied by Array or String were not fields of the document and thus will have an empty Array attached.
- :headers
- 
If set to :first_rowortrue, the initial row of the CSV file will be treated as a row of headers. If set to an Array, the contents will be used as the headers. If set to a String, the String is run through a call of CSV::parse_line() with the same:col_sep,:row_sep, and:quote_charas this instance to produce an Array of headers. This setting causes CSV#shift() to return rows as CSV::Row objects instead of Arrays and CSV#read() to return CSV::Table objects instead of an Array of Arrays.
- :return_headers
- 
When false, header rows are silently swallowed. If set totrue, header rows are returned in a CSV::Row object with identical headers and fields (save that the fields do not go through the converters).
- :write_headers
- 
When trueand:headersis set, a header row will be added to the output.
- :header_converters
- 
Identical in functionality to :converterssave that the conversions are only made to header rows. All built-in converters try to transcode headers to UTF-8 before converting. The conversion will fail if the data cannot be transcoded, leaving the header unchanged.
- :skip_blanks
- 
When set to a truevalue,CSVwill skip over any empty rows. Note that this setting will not skip rows that contain column separators, even if the rows contain no actual data. If you want to skip rows that contain separators but no content, consider using:skip_lines, or inspecting fields.compact.empty? on each row.
- :force_quotes
- 
When set to a truevalue,CSVwill quote all CSV fields it creates.
- :skip_lines
- 
When set to an object responding to match, every line matching it is considered a comment and ignored during parsing. When set to a String, it is first converted to a Regexp. When set tonilno line is considered a comment. If the passed object does not respond tomatch,ArgumentErroris thrown.
- :liberal_parsing
- 
When set to a truevalue,CSVwill attempt to parse input not conformant with RFC 4180, such as double quotes in unquoted fields.
See DEFAULT_OPTIONS for the default settings.
Options cannot be overridden in the instance methods for performance reasons, so be sure to set what you want here.
# File 'lib/csv.rb', line 1529
def initialize(data, = Hash.new) if data.nil? raise ArgumentError.new("Cannot parse nil as CSV") end # build the options for this read/write = DEFAULT_OPTIONS.merge() # create the IO object we will read from @io = data.is_a?(String) ? StringIO.new(data) : data # honor the IO encoding if we can, otherwise default to ASCII-8BIT @encoding = raw_encoding(nil) || ( if encoding = .delete(:internal_encoding) case encoding when Encoding; encoding else Encoding.find(encoding) end end ) || ( case encoding = .delete(:encoding) when Encoding; encoding when /\A[^:]+/; Encoding.find($&) end ) || Encoding.default_internal || Encoding.default_external # # prepare for building safe regular expressions in the target encoding, # if we can transcode the needed characters # @re_esc = "\\".encode(@encoding).freeze rescue "" @re_chars = /#{%"[-\\]\\[\\.^$?*+{}()|# \r\n\t\f\v]".encode(@encoding)}/ init_separators() init_parsers() init_converters() init_headers() init_comments() @force_encoding = !!(encoding || .delete(:encoding)) .delete(:internal_encoding) .delete(:external_encoding) unless .empty? raise ArgumentError, "Unknown options: #{.keys.join(', ')}." end # track our own lineno since IO gets confused about line-ends is CSV fields @lineno = 0 end
Class Method Details
    
      .filter(options = Hash.new) {|row| ... } 
      .filter(input, options = Hash.new) {|row| ... } 
      .filter(input, output, options = Hash.new) {|row| ... } 
    
  
This method is a convenience for building Unix-like filters for CSV data. Each row is yielded to the provided block which can alter it as needed. After the block returns, the row is appended to output altered or not.
The input and output arguments can be anything CSV::new() accepts (generally ::String or IO objects).  If not given, they default to ARGF and $stdout.
The options parameter is also filtered down to CSV::new() after some clever key parsing.  Any key beginning with :in_ or :input_ will have that leading identifier stripped and will only be used in the options Hash for the input object.  Keys starting with :out_ or :output_ affect only output.  All other keys are assigned to both objects.
The :output_row_sep option defaults to $INPUT_RECORD_SEPARATOR ($/).
# File 'lib/csv.rb', line 1104
def self.filter(*args) # parse options for input, output, or both , = Hash.new, {row_sep: $INPUT_RECORD_SEPARATOR} if args.last.is_a? Hash args.pop.each do |key, value| case key.to_s when /\Ain(?:put)?_(.+)\Z/ [$1.to_sym] = value when /\Aout(?:put)?_(.+)\Z/ [$1.to_sym] = value else [key] = value [key] = value end end end # build input and output wrappers input = new(args.shift || ARGF, ) output = new(args.shift || $stdout, ) # read, yield, write input.each do |row| yield row output << row end end
.foreach(path, options = Hash.new, &block)
This method is intended as the primary interface for reading CSV files.  You pass a path and any options you wish to set for the read.  Each row of file will be passed to the provided block in turn.
The options parameter can be anything CSV::new() understands.  This method also understands an additional :encoding parameter that you can use to specify the Encoding of the data in the file to be read. You must provide this unless your data is in Encoding::default_external().  CSV will use this to determine how to parse the data.  You may provide a second Encoding to have the data transcoded as it is read.  For example, encoding: "UTF-32BE:UTF-8" would read UTF-32BE data from the file but transcode it to UTF-8 before CSV parses it.
    
      .generate(str, options = Hash.new) {|csv| ... } 
      .generate(options = Hash.new) {|csv| ... } 
    
  
This method wraps a ::String you provide, or an empty default ::String, in a CSV object which is passed to the provided block.  You can use the block to append CSV rows to the ::String and when the block exits, the final ::String will be returned.
Note that a passed ::String is modified by this method. Call dup() before passing if you need a new ::String.
The options parameter can be anything CSV::new() understands.  This method understands an additional :encoding parameter when not passed a ::String to set the base Encoding for the output.  CSV needs this hint if you plan to output non-ASCII compatible data.
# File 'lib/csv.rb', line 1170
def self.generate(*args) # add a default empty String, if none was given if args.first.is_a? String io = StringIO.new(args.shift) io.seek(0, IO::SEEK_END) args.unshift(io) else encoding = args[-1][:encoding] if args.last.is_a?(Hash) str = String.new str.force_encoding(encoding) if encoding args.unshift(str) end csv = new(*args) # wrap yield csv # yield for appending csv.string # return final String end
.generate_line(row, options = Hash.new)
This method is a shortcut for converting a single row (Array) into a CSV ::String.
The options parameter can be anything CSV::new() understands.  This method understands an additional :encoding parameter to set the base Encoding for the output.  This method will try to guess your Encoding from the first non-nil field in row, if possible, but you may need to use this parameter as a backup plan.
The :row_sep option defaults to $INPUT_RECORD_SEPARATOR ($/) when calling this method.
# File 'lib/csv.rb', line 1200
def self.generate_line(row, = Hash.new) = {row_sep: $INPUT_RECORD_SEPARATOR}.merge() encoding = .delete(:encoding) str = String.new if encoding str.force_encoding(encoding) elsif field = row.find { |f| not f.nil? } str.force_encoding(String(field).encoding) end (new(str, ) << row).string end
.instance(data = $stdout, options = Hash.new)
This method will return a CSV instance, just like CSV::new(), but the instance will be cached and returned for all future calls to this method for the same data object (tested by Object#object_id()) with the same options.
If a block is given, the instance is passed to the block and the return value becomes the return value of the block.
# File 'lib/csv.rb', line 1064
def self.instance(data = $stdout, = Hash.new) # create a _signature_ for this method call, data object and options sig = [data.object_id] + .values_at(*DEFAULT_OPTIONS.keys.sort_by { |sym| sym.to_s }) # fetch or create the instance for this signature @@instances ||= Hash.new instance = (@@instances[sig] ||= new(data, )) if block_given? yield instance # run block, if given, returning result else instance # or return the instance end end
    
      .open(filename, mode = "rb", options = Hash.new) {|faster_csv| ... } 
      .open(filename, options = Hash.new) {|faster_csv| ... } 
      .open(filename, mode = "rb", options = Hash.new)  
      .open(filename, options = Hash.new)  
    
  
This method opens an IO object, and wraps that with CSV.  This is intended as the primary interface for writing a CSV file.
You must pass a filename and may optionally add a mode for Ruby's open().  You may also pass an optional Hash containing any options CSV::new() understands as the final argument.
This method works like Ruby's open() call, in that it will pass a CSV object to a provided block and close it when the block terminates, or it will return the CSV object when no block is provided.  (Note: This is different from the Ruby 1.8 CSV library which passed rows to the block.  Use CSV::foreach() for that behavior.)
You must provide a mode with an embedded Encoding designator unless your data is in Encoding::default_external().  CSV will check the Encoding of the underlying IO object (set by the mode you pass) to determine how to parse the data.   You may provide a second Encoding to have the data transcoded as it is read just as you can with a normal call to IO::open().  For example, "rb:UTF-32BE:UTF-8" would read UTF-32BE data from the file but transcode it to UTF-8 before CSV parses it.
An opened CSV object will delegate to many IO methods for convenience.  You may call:
- 
binmode() 
- 
binmode?() 
- 
close() 
- 
close_read() 
- 
close_write() 
- 
closed?() 
- 
eof() 
- 
eof?() 
- 
external_encoding() 
- 
fcntl() 
- 
fileno() 
- 
flock() 
- 
flush() 
- 
fsync() 
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internal_encoding() 
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ioctl() 
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isatty() 
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path() 
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pid() 
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pos() 
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pos=() 
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reopen() 
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seek() 
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stat() 
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sync() 
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sync=() 
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tell() 
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to_i() 
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to_io() 
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truncate() 
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tty?() 
# File 'lib/csv.rb', line 1275
def self.open(*args) # find the options Hash = if args.last.is_a? Hash then args.pop else Hash.new end # wrap a File opened with the remaining args with no newline # decorator file_opts = {universal_newline: false}.merge() begin f = File.open(*args, file_opts) rescue ArgumentError => e raise unless /needs binmode/ =~ e. and args.size == 1 args << "rb" file_opts = {encoding: Encoding.default_external}.merge(file_opts) retry end begin csv = new(f, ) rescue Exception f.close raise end # handle blocks like Ruby's open(), not like the CSV library if block_given? begin yield csv ensure csv.close end else csv end end
    
      .parse(str, options = Hash.new) {|row| ... } 
      .parse(str, options = Hash.new)  
    
  
This method can be used to easily parse CSV out of a ::String.  You may either provide a block which will be called with each row of the ::String in turn, or just use the returned ::Array of Arrays (when no block is given).
You pass your str to read from, and an optional options Hash containing anything CSV::new() understands.
.parse_line(line, options = Hash.new)
This method is a shortcut for converting a single line of a CSV String into an ::Array.  Note that if line contains multiple rows, anything beyond the first row is ignored.
The options parameter can be anything CSV::new() understands.
.read(path, *options)
Use to slurp a CSV file into an ::Array of Arrays.  Pass the path to the file and any options CSV::new() understands.  This method also understands an additional :encoding parameter that you can use to specify the Encoding of the data in the file to be read. You must provide this unless your data is in Encoding::default_external().  CSV will use this to determine how to parse the data.  You may provide a second Encoding to have the data transcoded as it is read.  For example, encoding: "UTF-32BE:UTF-8" would read UTF-32BE data from the file but transcode it to UTF-8 before CSV parses it.
# File 'lib/csv.rb', line 1355
def self.read(path, *) open(path, *) { |csv| csv.read } end
.readlines(*args)
Alias for CSV::read().
# File 'lib/csv.rb', line 1360
def self.readlines(*args) read(*args) end
.table(path, options = Hash.new)
A shortcut for:
CSV.read( path, { headers:           true,
                  converters:        :numeric,
                  header_converters: :symbol }.merge() )Instance Attribute Details
#col_sep (readonly)
The encoded :col_sep used in parsing and writing.  See .new for details.
# File 'lib/csv.rb', line 1580
attr_reader :col_sep
#encoding (readonly)
The Encoding CSV is parsing or writing in.  This will be the Encoding you receive parsed data in and/or the Encoding data will be written in.
# File 'lib/csv.rb', line 1653
attr_reader :encoding
#field_size_limit (readonly)
The limit for field size, if any. See .new for details.
# File 'lib/csv.rb', line 1592
attr_reader :field_size_limit
    #header_row?  ⇒ Boolean  (readonly)
  
Returns true if the next row read will be a header row.
# File 'lib/csv.rb', line 1794
def header_row? @use_headers and @headers.nil? end
#lineno (readonly)
The line number of the last row read from this file. Fields with nested line-end characters will not affect this count.
# File 'lib/csv.rb', line 1659
attr_reader :lineno
#quote_char (readonly)
The encoded :quote_char used in parsing and writing.  See .new for details.
# File 'lib/csv.rb', line 1590
attr_reader :quote_char
#row_sep (readonly)
The encoded :row_sep used in parsing and writing.  See .new for details.
# File 'lib/csv.rb', line 1585
attr_reader :row_sep
#skip_lines (readonly)
The regex marking a line as a comment. See .new for details
# File 'lib/csv.rb', line 1595
attr_reader :skip_lines
Instance Method Details
#<<(row) Also known as: #add_row, #puts
The primary write method for wrapped Strings and IOs, row (an ::Array or ::CSV::Row) is converted to CSV and appended to the data source.  When a ::CSV::Row is passed, only the row's fields() are appended to the output.
The data source must be open for writing.
# File 'lib/csv.rb', line 1688
def <<(row) # make sure headers have been assigned if header_row? and [Array, String].include? @use_headers.class parse_headers # won't read data for Array or String self << @headers if @write_headers end # handle CSV::Row objects and Hashes row = case row when self.class::Row then row.fields when Hash then @headers.map { |header| row[header] } else row end @headers = row if header_row? @lineno += 1 output = row.map(&@quote).join(@col_sep) + @row_sep # quote and separate if @io.is_a?(StringIO) and output.encoding != (encoding = raw_encoding) if @force_encoding output = output.encode(encoding) elsif (compatible_encoding = Encoding.compatible?(@io.string, output)) @io.set_encoding(compatible_encoding) @io.seek(0, IO::SEEK_END) end end @io << output self # for chaining end
#add_converter(var_name, const, name = nil, &converter) (private)
The actual work method for adding converters, used by both CSV.convert() and CSV.header_convert().
This method requires the var_name of the instance variable to place the converters in, the const Hash to lookup named converters in, and the normal parameters of the CSV.convert() and CSV.header_convert() methods.
# File 'lib/csv.rb', line 2202
def add_converter(var_name, const, name = nil, &converter) if name.nil? # custom converter instance_variable_get("@#{var_name}") << converter else # named converter combo = const[name] case combo when Array # combo converter combo.each do |converter_name| add_converter(var_name, const, converter_name) end else # individual named converter instance_variable_get("@#{var_name}") << combo end end end
#add_row(row)
Alias for #<<.
# File 'lib/csv.rb', line 1719
alias_method :add_row, :<<
#add_unconverted_fields(row, fields) (private)
This method injects an instance variable unconverted_fields into row and an accessor method for row called unconverted_fields().  The variable is set to the contents of fields.
# File 'lib/csv.rb', line 2289
def add_unconverted_fields(row, fields) class << row attr_reader :unconverted_fields end row.instance_eval { @unconverted_fields = fields } row end
    
      #convert(name)  
      #convert {|field| ... } 
      #convert {|field, field_info| ... } 
    
  
You can use this method to install a Converters built-in, or provide a block that handles a custom conversion.
If you provide a block that takes one argument, it will be passed the field and is expected to return the converted value or the field itself. If your block takes two arguments, it will also be passed a ::CSV::FieldInfo Struct, containing details about the field. Again, the block should return a converted field or the field itself.
# File 'lib/csv.rb', line 1737
def convert(name = nil, &converter) add_converter(:converters, self.class::Converters, name, &converter) end
#convert_fields(fields, headers = false) (private)
# File 'lib/csv.rb', line 2225
def convert_fields(fields, headers = false) # see if we are converting headers or fields converters = headers ? @header_converters : @converters fields.map.with_index do |field, index| converters.each do |converter| break if field.nil? field = if converter.arity == 1 # straight field converter converter[field] else # FieldInfo converter header = @use_headers && !headers ? @headers[index] : nil converter[field, FieldInfo.new(index, lineno, header)] end break unless field.is_a? String # short-circuit pipeline for speed end field # final state of each field, converted or original end end
#converters
Returns the current list of converters in effect. See .new for details. Built-in converters will be returned by name, while others will be returned as is.
# File 'lib/csv.rb', line 1602
def converters @converters.map do |converter| name = Converters.rassoc(converter) name ? name.first : converter end end
#each
Yields each row of the data source in turn.
Support for Enumerable.
The data source must be open for reading.
# File 'lib/csv.rb', line 1768
def each if block_given? while row = shift yield row end else to_enum end end
#encode_re(*chunks) (private)
Builds a regular expression in @encoding.  All chunks will be transcoded to that encoding.
# File 'lib/csv.rb', line 2312
def encode_re(*chunks) Regexp.new(encode_str(*chunks)) end
#encode_str(*chunks) (private)
Builds a ::String in @encoding.  All chunks will be transcoded to that encoding.
# File 'lib/csv.rb', line 2320
def encode_str(*chunks) chunks.map { |chunk| chunk.encode(@encoding.name) }.join('') end
#escape_re(str) (private)
This method is an encoding safe version of Regexp::escape().  It will escape any characters that would change the meaning of a regular expression in the encoding of str.  Regular expression characters that cannot be transcoded to the target encoding will be skipped and no escaping will be performed if a backslash cannot be transcoded.
# File 'lib/csv.rb', line 2304
def escape_re(str) str.gsub(@re_chars) {|c| @re_esc + c} end
    #force_quotes?  ⇒ Boolean 
  
Returns true if all output fields are quoted. See .new for details.
# File 'lib/csv.rb', line 1645
def force_quotes?() @force_quotes end
#gets
Alias for #shift.
# File 'lib/csv.rb', line 1955
alias_method :gets, :shift
    
      #header_convert(name)  
      #header_convert {|field| ... } 
      #header_convert {|field, field_info| ... } 
    
  
Identical to CSV#convert(), but for header rows.
Note that this method must be called before header rows are read to have any effect.
# File 'lib/csv.rb', line 1752
def header_convert(name = nil, &converter) add_converter( :header_converters, self.class::HeaderConverters, name, &converter ) end
#header_converters
Returns the current list of converters in effect for headers. See .new for details. Built-in converters will be returned by name, while others will be returned as is.
# File 'lib/csv.rb', line 1633
def header_converters @header_converters.map do |converter| name = HeaderConverters.rassoc(converter) name ? name.first : converter end end
#headers
Returns nil if headers will not be used, true if they will but have not yet been read, or the actual headers after they have been read.  See .new for details.
# File 'lib/csv.rb', line 1618
def headers @headers || true if @use_headers end
#init_comments(options) (private)
Stores the pattern of comments to skip from the provided options.
The pattern must respond to .match, else ArgumentError is raised. Strings are converted to a Regexp.
See also .new
# File 'lib/csv.rb', line 2187
def init_comments() @skip_lines = .delete(:skip_lines) @skip_lines = Regexp.new(@skip_lines) if @skip_lines.is_a? String if @skip_lines and not @skip_lines.respond_to?(:match) raise ArgumentError, ":skip_lines has to respond to matches" end end
#init_converters(options, field_name = :converters) (private)
Loads any converters requested during construction.
If field_name is set :converters (the default) field converters are set.  When field_name is :header_converters header converters are added instead.
The :unconverted_fields option is also activated for :converters calls, if requested.
# File 'lib/csv.rb', line 2140
def init_converters(, field_name = :converters) if field_name == :converters @unconverted_fields = .delete(:unconverted_fields) end instance_variable_set("@#{field_name}", Array.new) # find the correct method to add the converters convert = method(field_name.to_s.sub(/ers\Z/, "")) # load converters unless [field_name].nil? # allow a single converter not wrapped in an Array unless [field_name].is_a? Array [field_name] = [[field_name]] end # load each converter... [field_name].each do |converter| if converter.is_a? Proc # custom code block convert.call(&converter) else # by name convert.call(converter) end end end .delete(field_name) end
#init_headers(options) (private)
Stores header row settings and loads header converters, if needed.
# File 'lib/csv.rb', line 2170
def init_headers() @use_headers = .delete(:headers) @return_headers = .delete(:return_headers) @write_headers = .delete(:write_headers) # headers must be delayed until shift(), in case they need a row of content @headers = nil init_converters(, :header_converters) end
#init_parsers(options) (private)
Pre-compiles parsers and stores them by name for access during reads.
# File 'lib/csv.rb', line 2108
def init_parsers() # store the parser behaviors @skip_blanks = .delete(:skip_blanks) @field_size_limit = .delete(:field_size_limit) @liberal_parsing = .delete(:liberal_parsing) # prebuild Regexps for faster parsing esc_row_sep = escape_re(@row_sep) esc_quote = escape_re(@quote_char) @parsers = { # for detecting parse errors quote_or_nl: encode_re("[", esc_quote, "\r\n]"), nl_or_lf: encode_re("[\r\n]"), stray_quote: encode_re( "[^", esc_quote, "]", esc_quote, "[^", esc_quote, "]" ), # safer than chomp!() line_end: encode_re(esc_row_sep, "\\z"), # illegal unquoted characters return_newline: encode_str("\r\n") } end
#init_separators(options) (private)
Stores the indicated separators for later use.
If auto-discovery was requested for @row_sep, this method will read ahead in the @io and try to find one.  ARGF, STDIN, STDOUT, STDERR and any stream open for output only with a default @row_sep of $INPUT_RECORD_SEPARATOR ($/).
This method also establishes the quoting rules used for CSV output.
# File 'lib/csv.rb', line 2009
def init_separators() # store the selected separators @col_sep = .delete(:col_sep).to_s.encode(@encoding) @row_sep = .delete(:row_sep) # encode after resolving :auto @quote_char = .delete(:quote_char).to_s.encode(@encoding) if @quote_char.length != 1 raise ArgumentError, ":quote_char has to be a single character String" end # # automatically discover row separator when requested # (not fully encoding safe) # if @row_sep == :auto if [ARGF, STDIN, STDOUT, STDERR].include?(@io) or (defined?(Zlib) and @io.class == Zlib::GzipWriter) @row_sep = $INPUT_RECORD_SEPARATOR else begin # # remember where we were (pos() will raise an exception if @io is pipe # or not opened for reading) # saved_pos = @io.pos while @row_sep == :auto # # if we run out of data, it's probably a single line # (ensure will set default value) # break unless sample = @io.gets(nil, 1024) # extend sample if we're unsure of the line ending if sample.end_with? encode_str("\r") sample << (@io.gets(nil, 1) || "") end # try to find a standard separator if sample =~ encode_re("\r\n?|\n") @row_sep = $& break end end # tricky seek() clone to work around GzipReader's lack of seek() @io.rewind # reset back to the remembered position while saved_pos > 1024 # avoid loading a lot of data into memory @io.read(1024) saved_pos -= 1024 end @io.read(saved_pos) if saved_pos.nonzero? rescue IOError # not opened for reading # do nothing: ensure will set default rescue NoMethodError # Zlib::GzipWriter doesn't have some IO methods # do nothing: ensure will set default rescue SystemCallError # pipe # do nothing: ensure will set default ensure # # set default if we failed to detect # (stream not opened for reading, a pipe, or a single line of data) # @row_sep = $INPUT_RECORD_SEPARATOR if @row_sep == :auto end end end @row_sep = @row_sep.to_s.encode(@encoding) # establish quoting rules @force_quotes = .delete(:force_quotes) do_quote = lambda do |field| field = String(field) encoded_quote = @quote_char.encode(field.encoding) encoded_quote + field.gsub(encoded_quote, encoded_quote * 2) + encoded_quote end quotable_chars = encode_str("\r\n", @col_sep, @quote_char) @quote = if @force_quotes do_quote else lambda do |field| if field.nil? # represent nil fields as empty unquoted fields "" else field = String(field) # Stringify fields # represent empty fields as empty quoted fields if field.empty? or field.count(quotable_chars).nonzero? do_quote.call(field) else field # unquoted field end end end end end
#inspect
Returns a simplified description of the key CSV attributes in an ASCII compatible ::String.
# File 'lib/csv.rb', line 1962
def inspect str = ["<#", self.class.to_s, " io_type:"] # show type of wrapped IO if @io == $stdout then str << "$stdout" elsif @io == $stdin then str << "$stdin" elsif @io == $stderr then str << "$stderr" else str << @io.class.to_s end # show IO.path(), if available if @io.respond_to?(:path) and (p = @io.path) str << " io_path:" << p.inspect end # show encoding str << " encoding:" << @encoding.name # show other attributes %w[ lineno col_sep row_sep quote_char skip_blanks liberal_parsing ].each do |attr_name| if a = instance_variable_get("@#{attr_name}") str << " " << attr_name << ":" << a.inspect end end if @use_headers str << " headers:" << headers.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
    #liberal_parsing?  ⇒ Boolean 
  
Returns true if illegal input is handled. See .new for details.
# File 'lib/csv.rb', line 1647
def liberal_parsing?() @liberal_parsing end
#parse_headers(row = nil) (private)
This method is used to turn a finished row into a ::CSV::Row.  Header rows are also dealt with here, either by returning a ::CSV::Row with identical headers and fields (save that the fields do not go through the converters) or by reading past them to return a field row. Headers are also saved in @headers for use in future rows.
When nil, row is assumed to be a header row not based on an actual row of the stream.
# File 'lib/csv.rb', line 2254
def parse_headers(row = nil) if @headers.nil? # header row @headers = case @use_headers # save headers # Array of headers when Array then @use_headers # CSV header String when String self.class.parse_line( @use_headers, col_sep: @col_sep, row_sep: @row_sep, quote_char: @quote_char ) # first row is headers else row end # prepare converted and unconverted copies row = @headers if row.nil? @headers = convert_fields(@headers, true) @headers.each { |h| h.freeze if h.is_a? String } if @return_headers # return headers return self.class::Row.new(@headers, row, true) elsif not [Array, String].include? @use_headers.class # skip to field row return shift end end self.class::Row.new(@headers, convert_fields(row)) # field row end
#puts(row)
Alias for #<<.
# File 'lib/csv.rb', line 1720
alias_method :puts, :<<
#raw_encoding(default = Encoding::ASCII_8BIT) (private)
Returns the encoding of the internal IO object or the default if the encoding cannot be determined.
#read Also known as: #readlines
Slurps the remaining rows and returns an ::Array of Arrays.
The data source must be open for reading.
#readline
Alias for #shift.
# File 'lib/csv.rb', line 1956
alias_method :readline, :shift
#readlines
Alias for #read.
# File 'lib/csv.rb', line 1791
alias_method :readlines, :read
    #return_headers?  ⇒ Boolean 
  
Returns true if headers will be returned as a row of results. See .new for details.
# File 'lib/csv.rb', line 1625
def return_headers?() @return_headers end
#rewind
Rewinds the underlying IO object and resets CSV's lineno() counter.
# File 'lib/csv.rb', line 1672
def rewind @headers = nil @lineno = 0 @io.rewind end
#shift Also known as: #gets, #readline
The primary read method for wrapped Strings and IOs, a single row is pulled from the data source, parsed and returned as an ::Array of fields (if header rows are not used) or a ::CSV::Row (when header rows are used).
The data source must be open for reading.
# File 'lib/csv.rb', line 1805
def shift ######################################################################### ### This method is purposefully kept a bit long as simple conditional ### ### checks are faster than numerous (expensive) method calls. ### ######################################################################### # handle headers not based on document content if header_row? and @return_headers and [Array, String].include? @use_headers.class if @unconverted_fields return add_unconverted_fields(parse_headers, Array.new) else return parse_headers end end # # it can take multiple calls to <tt>@io.gets()</tt> to get a full line, # because of \r and/or \n characters embedded in quoted fields # in_extended_col = false csv = Array.new loop do # add another read to the line unless parse = @io.gets(@row_sep) return nil end parse.sub!(@parsers[:line_end], "") if csv.empty? # # I believe a blank line should be an <tt>Array.new</tt>, not Ruby 1.8 # CSV's <tt>[nil]</tt> # if parse.empty? @lineno += 1 if @skip_blanks next elsif @unconverted_fields return add_unconverted_fields(Array.new, Array.new) elsif @use_headers return self.class::Row.new(Array.new, Array.new) else return Array.new end end end next if @skip_lines and @skip_lines.match parse parts = parse.split(@col_sep, -1) if parts.empty? if in_extended_col csv[-1] << @col_sep # will be replaced with a @row_sep after the parts.each loop else csv << nil end end # This loop is the hot path of csv parsing. Some things may be non-dry # for a reason. Make sure to benchmark when refactoring. parts.each do |part| if in_extended_col # If we are continuing a previous column if part[-1] == @quote_char && part.count(@quote_char) % 2 != 0 # extended column ends csv[-1] = csv[-1].push(part[0..-2]).join("") if csv.last =~ @parsers[:stray_quote] raise MalformedCSVError, "Missing or stray quote in line #{lineno + 1}" end csv.last.gsub!(@quote_char * 2, @quote_char) in_extended_col = false else csv.last.push(part, @col_sep) end elsif part[0] == @quote_char # If we are starting a new quoted column if part.count(@quote_char) % 2 != 0 # start an extended column csv << [part[1..-1], @col_sep] in_extended_col = true elsif part[-1] == @quote_char # regular quoted column csv << part[1..-2] if csv.last =~ @parsers[:stray_quote] raise MalformedCSVError, "Missing or stray quote in line #{lineno + 1}" end csv.last.gsub!(@quote_char * 2, @quote_char) elsif @liberal_parsing csv << part else raise MalformedCSVError, "Missing or stray quote in line #{lineno + 1}" end elsif part =~ @parsers[:quote_or_nl] # Unquoted field with bad characters. if part =~ @parsers[:nl_or_lf] raise MalformedCSVError, "Unquoted fields do not allow " + "\\r or \\n (line #{lineno + 1})." else if @liberal_parsing csv << part else raise MalformedCSVError, "Illegal quoting in line #{lineno + 1}." end end else # Regular ole unquoted field. csv << (part.empty? ? nil : part) end end # Replace tacked on @col_sep with @row_sep if we are still in an extended # column. csv[-1][-1] = @row_sep if in_extended_col if in_extended_col # if we're at eof?(), a quoted field wasn't closed... if @io.eof? raise MalformedCSVError, "Unclosed quoted field on line #{lineno + 1}." elsif @field_size_limit and csv.last.sum(&:size) >= @field_size_limit raise MalformedCSVError, "Field size exceeded on line #{lineno + 1}." end # otherwise, we need to loop and pull some more data to complete the row else @lineno += 1 # save fields unconverted fields, if needed... unconverted = csv.dup if @unconverted_fields # convert fields, if needed... csv = convert_fields(csv) unless @use_headers or @converters.empty? # parse out header rows and handle CSV::Row conversions... csv = parse_headers(csv) if @use_headers # inject unconverted fields and accessor, if requested... if @unconverted_fields and not csv.respond_to? :unconverted_fields add_unconverted_fields(csv, unconverted) end # return the results break csv end end end
    #skip_blanks?  ⇒ Boolean 
  
Returns true blank lines are skipped by the parser. See .new for details.
# File 'lib/csv.rb', line 1643
def skip_blanks?() @skip_blanks end
    #unconverted_fields?  ⇒ Boolean 
  
Returns true if unconverted_fields() to parsed results.  See .new for details.
# File 'lib/csv.rb', line 1612
def unconverted_fields?() @unconverted_fields end
    #write_headers?  ⇒ Boolean 
  
Returns true if headers are written in output. See .new for details.
# File 'lib/csv.rb', line 1627
def write_headers?() @write_headers end