Parsing data to a csv file on a new line - ruby - ruby

Question

I am trying to export data that I 'get' into a new csv file. Currently, my code below posts everyone onto a single line until it fills up and then it continues to the next line.
I would like to have it where when data is imported, it starts on the following line below, creating a list of transactions.
def export_data
File.open('coffee_orders.csv', 'a+') do |csv|
puts #item_quantity = [Time.now, #item_name, #amount]
csv << #item_quantity
end
end

Answer 1

Basing it on your starting code, I'd do something like:
def export_data
File.open('coffee_orders.csv', 'a') do |csv|
csv << [Time.now, #item_name, #amount].join(', ')
end
end
Or:
def export_data
File.open('coffee_orders.csv', 'a') do |csv|
csv << '%s, %s, %s' % [Time.now, #item_name, #amount].map(&:to_s)
end
end
Notice, it's not necessary to use 'a+' to append to a file. Instead use 'a' only unless you absolutely need "read" mode while the file is open also. Here's what the IO.new documentation says:
"a" Write-only, starts at end of file if file exists,
otherwise creates a new file for writing.
"a+" Read-write, starts at end of file if file exists,
otherwise creates a new file for reading and
writing.
The way I'd write it for myself would be something like:
CSV_FILENAME = 'coffee_orders.csv'
def export_data
csv_has_content = File.size?(CSV_FILENAME)
CSV.open(CSV_FILENAME, 'a') do |csv|
csv << %w[Time Item Amount] unless csv_has_content
csv << [Time.now, #item_name, #amount]
end
end
This uses Ruby's CSV class to handle all the ins-and-outs. It checks to see if the file already exists, and if it has no content it writes the header before writing the content.

Answer 2

Try this. It will add a new line after each transaction. When you append to it next, it will be from a new line.
def export_data
File.open('coffee_orders.csv', 'a+') do |csv|
csv.puts #item_quantity = [Time.now, #item_name, #amount]
end
end
Although by looking the extension, you would probably want to confine it to csv format.
def export_data
File.open('coffee_orders.csv', 'a+') do |csv|
#item_quantity = [Time.now, #item_name, #amount]
csv.puts #item_quantity.join(',')
end
end