This is something that seems ridiculously hard in Rails.
I think something like this might work:
<%= f.fields_for :session_instructors do |si| %>
<%= si.collection_select :instructor_ids, current_user.instructors, :id, :name, multiple: true>
<% end %>
This should create a form element which will set sezzion[session_instructors_attributes][instructor_ids].
Although I'm not sure if that's actually what you want. I've never tried this using a multi select. If it doesn't work, you could also try getting rid of the fields_for
and just using f.collection_select
. If you're willing to use a checkbox, I can show you how to do that for sure.
I hope that helps.
Edit:
Here's how I would usually do it with a check_box
:
<%= f.fields_for :session_instructors do |si| %>
<%= si.hidden_field "instructor_ids[]" %>
<% current_user.instructors.each do |i| %>
<%= si.check_box "instructor_ids[]", i.id, i.sezzions.include?(@sezzion), id: "instructor_ids_#{i.id}" %>
<%= label_tag "instructor_ids_#{i.id}", i.name %>
<% end %>
<% end%>
There are a couple "gotchas!" with this method. When editing a model, if you deselect all checkboxes then it won't send the parameter at all. That's why the hidden_field
is necessary. Also, you need to make sure each form element has a unique id
field. Otherwise only the last entry is sent. That's why I manually set the value myself.
I copy pasted and then edited. Hopefully I got the syntax close enough where you can get it to work.
FINAL EDIT:
Per Sayanee's comment below, the answer was a bit simpler than I thought:
<%= f.collection_select :instructor_ids, current_user.instructors, :id, :name, {}, {:multiple => true} %>