Passing an array through a hidden_field_tag in Rails

Question

I did find this question on SO, but it didn't help, really.

So, I'd like to pass an array through a hidden field tag. As of now my code is:

<%= hidden_field_tag "article_ids", @articles.map(&:id) %>

This obviously does not work since it passes the ids as a string.

How do i do it?

Answer 1

Hi maybe there is better solution but you may try

<% @articles.map(&:id).each do |id| %>
  <%= hidden_field_tag "article_ids[]", id %>
<% end %>

Answer 2

You could try to parse it to and from json:

articles_list = @articles.map(&:id).to_json # gives u: [1,2,3,4,5]
                                            # note that the result is a string instead of an array
article_ids = JSON.parse(articles_list)

Or you could just make use of comma separated string:

articles_list = @articles.map(&:id).join(",") # gives u: 1,2,3,4,5
                                              # note that this result is a string also
article_ids = articles_list.split(/,/).map(&:to_i)

Answer 3

The following worked for me on Rails 4.1.10

<% @your_array.map().each do |array_element| %>
    <%= hidden_field_tag "your_array[]", array_element %>
<% end %>

Answer 4

On Rails 4 you can do:

<% @articles.map(&:id).each do |id| %>
  <%= hidden_field_tag "article_ids", value: id, multiple: true %>
<% end %>

As Rails will automatically append "[]" to the name of the field (when using multiple) and the controller that receives the form will see that as an array of values.