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 => {:multipart => true}) do |f| %>     <table>         <tr>             <td><%= f.label("File:") %></td>             <td><%= f.file_field(:filename) %></td>         </tr>     </table>         <%= f.submit("Submit") %>     <% end %> 

Clicking Submit redirects me to another page (create.html.erb). The file was loaded fine, and I was able to read the contents just fine in this second page. I am trying to show the number of lines in the .csv file in this second page.

My controller (semi-pseudocode):

class UpcsvController < ApplicationController     def index     end      def create         file = params[:upcsv][:filename]         ...         #params[:upcsv][:file_length] = file.length # Show number of lines in the file         #params[:upcsv][:file_length] = file.size         ...     end end 

Both file.length and file.size returns '91' when my file only contains 7 lines. From the Rails documentation that I read, once the Submit button is clicked, Rails creates a temp file of the uploaded file, and the params[:upcsv][:filename] contains the contents of the temp/uploaded file and not the path to the file. And I don't know how to extract the number of lines in my original file. What is the correct way to get the number of lines in the file?

My create.html.erb:

<table>     <tr>         <td>File length:</td>         <td><%= params[:upcsv][:file_length] %></td>     </tr> </table> 

I'm really new at Rails (just started last week), so please bear with my stupid questions.

Thank you!

Update: apparently that number '91' is the number of individual characters (including carriage return) in my file. Each line in my file has 12 digits + 1 newline = 13. 91/13 = 7.

Answer 1

All of the solutions listed here actually load the entire file into memory in order to get the number of lines. If you're on a Unix-based system a much faster, easier and memory-efficient solution is:

`wc -l #{your_file_path}`.to_i