Ruby 1.9.2 リファレンスマニュアル > ライブラリ一覧 > csvライブラリ > CSVクラス

class CSV

クラスの継承リスト: CSV < Enumerable < Object < Kernel < BasicObject
extend: Forwardable

要約

このクラスは CSV ファイルやデータに対する完全なインターフェイスを提供します。

読み込み

# ファイルから一行ずつ
CSV.foreach("path/to/file.csv") do |row|
  # use row here...
end

# ファイルから一度に
arr_of_arrs = CSV.read("path/to/file.csv")

# 文字列から一行ずつ
CSV.parse("CSV,data,String") do |row|
  # use row here...
end

# 文字列から一行ずつ
arr_of_arrs = CSV.parse("CSV,data,String")

書き込み

# ファイルへ書き込み
CSV.open("path/to/file.csv", "wb") do |csv|
  csv << ["row", "of", "CSV", "data"]
  csv << ["another", "row"]
  # ...
end

# 文字列へ書き込み
csv_string = CSV.generate do |csv|
  csv << ["row", "of", "CSV", "data"]
  csv << ["another", "row"]
  # ...
end

一行変換

csv_string = ["CSV", "data"].to_csv   # => "CSV,data"
csv_array  = "CSV,String".parse_csv   # => ["CSV", "String"]

ショートカット

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 と文字エンコーディング (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, <tt>:col_sep</tt>, <tt>:row_sep</tt>, and <tt>:quote_char</tt> must be transcoded to match your data. Hopefully this makes the entire process feel transparent, since CSV's defaults should just magically work for you 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}[mailto:james@grayproductions.net] any issues you find with it.

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