Count the length (number of lines) of a CSV file?

Question

I have a form (Rails) which allows me to load a .csv file using the file_field. In the view:

    <% form_for(:upcsv, :html => {:multipa         


        

Answer 1

Just to demonstrate what IO#readlines does:

if you had a file like this: "asdflkjasdlkfjsdakf\n asdfjljdaslkdfjlsadjfasdflkj\n asldfjksdjfa\n"

in rails you'd do, say:

file = File.open(File.join(Rails.root, 'lib', 'file.json'))
lines_ary = IO.readlines(file)
lines_ary.count #=> 3

IO#readlines converts a file into an array of strings using the \n (newlines) as separators, much like commas so often do, so it's basically like

str.split(/\n/)

In fact, if you did

 x = file.read

this

 x.split(/\n/)

would do the same thing as file.readlines

** IO#readlines can be really handy when dealing with files which have a repeating line structure ("child_id", "parent_ary", "child_id", "parent_ary",...) etc