Get selected item from dropdown menu via ruby - html

Question

My problem is that I have a form that like:
<select name="Users">
<option value=""selected>Select user to add</option>
<% notShareWith.each do |user| %>
<option value=<%user.id%>><%=user.name+" "+user.email%></option>
<% end %>
</select>
<% form_for #imageuser do |f| %>
<%= f.hidden_field :user_id ,:value => 5 %>
<%= f.hidden_field :image_id ,:value => #image.id %>
<% end %>
My drop down menu works fine and it list the users that have access. I can revoke access and everything. I have no clue how to know what option is selected from the drop down menu or how to submit that to the image users form. I am using:
<% form_for #imageuser do |f| %>
<%= f.hidden_field :user_id ,:value => 5 %>
<%= f.hidden_field :image_id ,:value => #image.id %>
<% end %>
to submit the user that is selected but I need to know what the value of the selected item is so I can pass said value into:
<%= f.hidden_field :user_id ,:value => 5 %>
Thanks again for the help.

Answer 1

You can also use options_from_collection_for_select
Something like this should work
<% form_for #imageuser do |f| %>
<%= f.select :user_id, options_from_collection_for_select(notShareWith, 'id', 'name'), prompt: 'Select user to add' %>
<%= f.hidden_field :image_id ,:value => #image.id %>
<% end %>

Answer 2

Use collection_select helper instead, something like this:
<%= f.collection_select(:user_id, notShareWith.map { |user| user.id }, :id, :id, :prompt => 'Select') %>
Then, grab the selected value like: params[:user_id]

Answer 3

To fill the selected id of user in your form you have to do several steps
First, add id attribute in your option
<select id="user_id" name="Users">
<option value=""selected>Select user to add</option>
<% notShareWith.each do |user| %>
<option value=<%user.id%>><%=user.name+" "+user.email%></option>
<% end %>
</select>
Then, you can use javascript to pass into imageuser form:
<script type="text/javascript">
$( document ).ready(function() {
$("#user_id").change(function(){
selected = $(this).val();
$("#imageuser_user_id").val(selected);
});
});
</script
NOTE:
You'd better use select_tag helper to create select option
<%= select_tag 'user_id', options_for_select(notShareWith.collect{ |u| ["#{u.name} #{user.email}", u.id]}, prompt: "Select user to add") %>