write csv in ruby 1.9 and CSV::Writer
The csv library is still there, but CSV::Writer is not. According to the csv.rb in 1.9.0:
# I'm sure I'll miss something, but I'll try to mention most of the major
# differences I am aware of, to help others quickly get up to speed:
#
# === CSV Parsing
#
# * This parser is m17n aware. See CSV for full details.
# * This library has a stricter parser and will throw MalformedCSVErrors on
# problematic data.
# * This library has a less liberal idea of a line ending than CSV. What you
# set as the <tt>:row_sep</tt> is law. It can auto-detect your line endings
# though.
# * The old library returned empty lines as <tt>[nil]</tt>. This library calls
# them <tt>[]</tt>.
# * This library has a much faster parser.
#
# === Interface
#
# * CSV now uses Hash-style parameters to set options.
# * CSV no longer has generate_row() or parse_row().
# * The old CSV's Reader and Writer classes have been dropped.
# * CSV::open() is now more like Ruby's open().
# * CSV objects now support most standard IO methods.
# * CSV now has a new() method used to wrap objects like String and IO for
# reading and writing.
# * CSV::generate() is different from the old method.
# * CSV no longer supports partial reads. It works line-by-line.
# * CSV no longer allows the instance methods to override the separators for
# performance reasons. They must be set in the constructor.
A little later on, there's an example of how to write line-by-line (as well as other methods of writing):
# === To a File
#
# CSV.open("path/to/file.csv", "wb") do |csv|
# csv << ["row", "of", "CSV", "data"]
# csv << ["another", "row"]
# # ...
# end
Geoff Gustafson
Developer and Security analyst. Python, Ruby, C/C++ and Bitcoin early adopter and developer
Updated on July 09, 2022Comments
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Geoff Gustafson almost 2 years
i have a code that works fine with ruby 1.87 but dont works with ruby 1.9. It says that CSV::Writer is undeclared but it still part of the rdoc. Does the csv api changed, after the fastercsv merge, or not?
my code:
require 'csv' def self.export_csv file_name = File.join(RAILS_ROOT, 'public','csv',"#{start_date_f}_#{end_date_f}.csv") return file_name if File.exist?(file_name) @results = find(:all) header_row = [] outfile = File.open(file_name, 'wb') CSV::Writer.generate(outfile) do |csv| header_row = ['gateway_id','created', 'gateway_status_id', 'panel_id', 'panel_status','volts_out', 'amps_out', 'temp','aid' ,'sid', 'pisid'] csv << header_row end end
The error that i receive: NameError: uninitialized constant CSV::Writer
Note that require 'csv' is there. i try it in my console, when i do the require 'csv', it works, but as soon as i call CSV::Writer i receive that error. This code works fine with ruby 1.87, so it makes me think that it is a ruby 1.9 csv problem since it was merged with fasterCSV.