Rails: Hidden fields not passing values

Question

I am trying to create a form for a site administrator to associate events with a list of previous speakers. The administrator navigates to the speaker, clicks on a button to "Add to event" and a form comes up asking for which event the speaker is attending. The speaker is supposed to be passed in as a hidden field, and the events are listed via a collection select. Unfortunately, the speaker id is not passing into the database when I submit the form.

Why is my form is not saving values from the hidden field, and how do I about fixing this? Values from the collection select are passing.

<%= form_for(@event_speaker) do |f| %>
  <% if @event_speaker.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@event_speaker.errors.count, "error") %> prohibited this event_speaker from being saved:</h2>

      <ul>
      <% @event_speaker.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <p><%= @speaker.first_name %></p>
  <div class="actions">
    <%= @speaker.id %>
    <%= f.hidden_field(:speaker) %>
    <%= hidden_field_tag('speaker_id',@speaker.id)  %>
  </div>
  <div class="field">
    <%= f.label :event %><br>
    <%= f.collection_select(:event_id, @upcoming_events, :id, :name)%>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

And the controller:

def new
    @event_speaker = EventSpeaker.new
    @speaker = Speaker.find(params[:speaker_id])
    @event_speaker.speaker_id = @speaker
    @Time = Time.now
    @upcoming_events = Event.all
  end

  # GET /event_speakers/1/edit
  def edit
  end

  # POST /event_speakers
  # POST /event_speakers.json
  def create
    @event_speaker = EventSpeaker.new(event_speaker_params)

    respond_to do |format|
      if @event_speaker.save
        format.html { redirect_to @event_speaker, notice: 'Event speaker was successfully created.' }
        format.json { render action: 'show', status: :created, location: @event_speaker }
      else
        format.html { render action: 'new' }
        format.json { render json: @event_speaker.errors, status: :unprocessable_entity }
      end
    end
  end

And...

 def event_speaker_params
      params.require(:event_speaker).permit(:speaker_id,:event_id) 
    end

Answer 1

You should do

<%= f.hidden_field :speaker_id, :value => @speaker.id %>

This will generate your speaker_id nested inside event_speaker so your form will look like this:

<%= form_for(@event_speaker) do |f| %>
  <% if @event_speaker.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@event_speaker.errors.count, "error") %> prohibited this event_speaker from being saved:</h2>
      <ul>
        <% @event_speaker.errors.full_messages.each do |msg| %>
          <li><%= msg %></li>
        <% end %>
      </ul>
    </div>
  <% end %>

  <p><%= @speaker.first_name %></p>
  <div class="actions">
    <%= f.hidden_field :speaker_id, :value => @speaker.id %>
  </div>
  <div class="field">
    <%= f.label :event %><br>
    <%= f.collection_select(:event_id, @upcoming_events, :id, :name)%>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

For details checkout hidden field in rails