In Rails, how to handle multiple checked checkboxes, just split on the , or?

Question

Curious what the \'rails way\' of handling the situation when a user checks multiple checkboxes (with the same name value), and it gets posted back to the controller.

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Answer 1

Here is an example of view and controller for example where multiple cleaners can be in multiple cities.

<%= form_for(@cleaner) do |f| %>
  <p>
    <%= f.label :cities %><br />
    <% for city in City.all %>
      <%= check_box_tag "cleaner[city_ids][]", city.id, @cleaner.cities.include?(city) %>
      <%=h city.name %><br />
    <% end %>
  </p>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

And in controller

def cleaner_params
  params.require(:cleaner).permit(city_ids: [])
end

You can find complete tutorial on "rails way" of doing this https://kolosek.com/rails-join-table/

Answer 2

If you want to use a checked param you have to write this :

check_box_tag "tag_ids[]", 1, true

And not this :

check_box_tag 'tag_ids[]', 1, true

It took me a while to figure out, I hope it will help someone.

Answer 3

In addition to Chuck Callebs answer, I realised that with sending an empty string instead of nil or false as unchecked value, Rails will understand to remove associated ids on an update action:

<%= f.check_box :tag_ids, {multiple: true}, tag.id, '' %>

Answer 4

f.check_box :tag_ids, {multiple: true}, 1, nil

Is the right answer:

Here is the reason, there is a 'multiple: true' option that allows your input to be placed in an array. If there isn't a multiple: true option this will not be allowed.

Answer 5

The easiest way of doing this is to set those checkboxes up to become an array.

HTML:

<input type="checkbox" name="tag_ids[]" value="1" />
<input type="checkbox" name="tag_ids[]" value="2" />
<input type="checkbox" name="tag_ids[]" value="3" />

Controller:

tag_ids = params[:tag_ids]

(Of course, you'd probably be using form_for-based helpers in the view, and therefore mass-assigning the tag IDs. This is just the most generic example.)