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

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

  <div class="field">
    <%= f.label :latitude %><br>
    <%= f.text_field :latitude %>
  </div>
  <div class="field">
    <%= f.label :longitude %><br>
    <%= f.text_field :longitude %>
  </div>
  <div class="field">
    <%= f.label :user_id %><br>
    <%= f.number_field :user_id %>
  </div>
  <div class="field">
    <%= f.label :timestamp %><br>
    <%= f.datetime_select :timestamp %>
  </div>
  <div class="field">
    <%= f.label :message %><br>
    <%= f.text_area :message %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

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

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

  <div class="field">
    <%= f.label :latitude %><br>
    <%= f.text_field :latitude %>
  </div>
  <div class="field">
    <%= f.label :longitude %><br>
    <%= f.text_field :longitude %>
  </div>
  <div class="field">
    <%= f.label :timestamp %><br>
    <%= f.datetime_select :timestamp %>
  </div>
  <div class="field">
    <%= f.label :message %><br>
    <%= f.text_area :message %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

Remove user_id field from crumb form
Remove user_id field from crumb form
