Question

I’m working on my first application and I need some help with allowing my users to download a text file with certain variables that are being displayed on the page.

Take a shopping list for example.
Let’s say you allow your users to create a shopping list of products, and then display the shopping list with the items on a shopping list page,

e.g. localhost:3000/list/my-list

Take a look at the example code below (which is probably incorrect):

File.open('shopping_list.txt', 'w') do |file|
  file.puts 'Item 1: #{product_1.name}'
  file.puts 'Item 2: #{product_2.name}'
  file.puts 'Item 3: #{product_3.name}'
end

Which then creates a text file that has the following content:

Item 1: Eggs
Item 2: Butter
Item 3: Bread

Users should then be able to download this file (i don’t want this file to be stored on the server) via a download link.

I have no idea how to achieve this, but I’m hoping you guys can guide me. 😀

TL;DR

• create text files populated with model data (perhaps create a method to achieve this?)
• text files should not be stored on the server, but created as users click the download button (not sure if this is the rails way but perhaps someone could show me a better way)

Answer 1

I am assuming there is a resource for List with the attribute name as the name of the list and a list has_many Item which has an attribute description

First off, create a download path change your routes config/routes.rb

resources :lists do
  member {get "download"}
end

Now if you run a rake routes in the console you should see a route like

/lists/:id/download

Whats more you should now have the helpers download_list_url & download_list_path to use in your view like

<ul>
<% @lists.each do |list| %>
  <li> <%= list.name %> - <%= link_to 'Download List', download_list_path(list) %> </li>
<% end %>
</ul>

In your lists_controller add the action, and as you dont actually want to keep the file on the server disk just stream the data as a string

def download
  list = List.find(params[:id])
  send_data list.as_file,
    :filename => "#{list.name}.txt",
    :type => "text/plain"
end

Finally you see I have used a as_file method which you should add to the model (I prefer not to do this stuff in controllers, fat models, skinny controllers). So in the List model

def as_file
  output = [self.name]
  self.items.each {|item| output << item.description }
  output.join("\n")
end