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?

score 35 · Accepted Answer · edited Feb 12 '16 at 09:48

35

Hi maybe there is better solution but you may try

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

edited Feb 12 '16 at 09:48

Rajesh Omanakuttan

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answered Dec 22 '10 at 12:16

Bohdan

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score 2 · Answer 2 · answered May 29 '16 at 11:28

2

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 %>

answered May 29 '16 at 11:28

Conor

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score 1 · Answer 3 · answered May 09 '16 at 13:11

1

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.

answered May 09 '16 at 13:11

Bruno Peres

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hm, this doesnt work for me at all, it will result in a parameter `"article_ids"=>"{:value=>123, :multiple=>true}"` – Ninigi Jun 15 '16 at 03:31
@Ninigi I lost the code to test the output, can you try `<%= hidden_field "article_ids", id, multiple: true %>` and see if it works then I'll update the answer? (using `hidden_field` helper and without `value:`) – Bruno Peres Jun 15 '16 at 13:06
doesnt work either, it just ignores the multiple option. I've taken a small look at the code for the hidden_field helper. In the end, it uses the generic `tag` method and I did not find anything about multiple. Maybe this is deprecated? – Ninigi Jun 16 '16 at 04:25
Make sure to include a `hidden_field_tag` with an empty Array or nil value, otherwise, there will be no way for the User to "uncheck" all the values. – Joshua Pinter Nov 08 '20 at 18:08

score 1 · Answer 4 · answered Dec 22 '10 at 12:15

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)

Passing an array through a hidden_field_tag in Rails

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