Select value is null after submit (Rails)

Question

I have a form on Rails where I add some fields to the database, it adds the text fields properly but it always adds the select value as null, I populated the options with javascript

new.html.erb

<%= form_for @person, url: people_path, remote: false do |f| %>
    <div class="form-group  row"><label class="col-sm-2 col-form-label">*Name</label>
        <div class="col-sm-3">
            <%= f.text_field :name, class:"form-control" %>
        </div>
    </div>

<div class="form-group row"><label class="col-sm-2 col-form-label">*Country</label>
    <div class="col-sm-3">
       <%= select_tag :hcountry, nil, class:"select2_demo_1 form-control" %>
          <%=hidden_field_tag 'country'%>
    </div>

<label class="col-form-label">State</label>
    <div class="col-sm-3">
        <%= select_tag :hcity, nil, class:"select2_demo_1 form-control"%>
    </div>

        <script language="javascript">
            populateCountries("hcountry", "hcity");
        </script>     
</div>


<!-- Buttons -->
    <div class="hr-line-dashed"></div>
        <div class="form-group row">
            <div class="col-sm-4 col-sm-offset-2">
                <%= f.submit :Submit , class: 'btn btn-primary btn-sm'%>
                <%= link_to "Cancel", controller:"mainpages", action:"index", :html=>{:class=> "btn btn-primary btn-sm"}%>
             </div>
     </div>
  <% end %>                       

hidden-fields.js

$( "#hcountry" ).change(function() {
    var h =  $("#hcountry").val();
    $("#country").val(h);
});

people_controller.erb

  def new
    @person = Person.new
  end

  def create
    @person = Person.new(person_params)
      if @person.save 
        redirect_to :root
    end
  end

  private
    def person_params
      params.require(:person).permit(:name,:country, :city)
    end

The javascript part is working since I wrote an alert to print the hidden field's value and it's actually printing the selected value, the problem is that it shows null in the database.

I didn't show the javascript to populate the options because it's way too long and I don't consider it relevant.

Answer 1

Use f.hidden_field :country instead of hidden_field_tag 'country' and chenge your script to update the value of #person_country instead of #country .

The way you have the code now the "country" value won't be nested inside params[:person] , it will be just params[:country] . Check the elements' ids and names, and check the params on the server log and you'll see that.