Ruby on rails 培训满时不显示问题

我正在创建一个应用程序，用户可以在其中预订培训。我说过，当训练达到最大时，没有人可以再预订了。我试图在出现这种情况时显示一个错误，但错误没有出现，方法有效，它不允许任何人加入培训，但应用程序需要告诉用户，他无法预订，因为培训已满

我想要一些帮助，以了解为什么错误没有显示，以及如何修复它

预订模式：

class Booking < ApplicationRecord
  belongs_to :user
  belongs_to :training
  validates :user_id, presence: true
  validates :training_id, presence: true
  validate :training_not_full?, on: :create



private

  def training_not_full?
    errors.add(:training, "Full training. Try another hour") unless training.can_book?
  end

end

class Training < ApplicationRecord
  has_many :users, through: :bookings
  has_many :bookings

  def can_book?
    bookings.count < slots
  end

end

培训模式：

class Booking < ApplicationRecord
  belongs_to :user
  belongs_to :training
  validates :user_id, presence: true
  validates :training_id, presence: true
  validate :training_not_full?, on: :create



private

  def training_not_full?
    errors.add(:training, "Full training. Try another hour") unless training.can_book?
  end

end

class Training < ApplicationRecord
  has_many :users, through: :bookings
  has_many :bookings

  def can_book?
    bookings.count < slots
  end

end

显示培训视图：

<div class="row">
    <section>
      <h1>
HOUR: <%= @training.hour %>
      </h1>
    </section>
    <section>
      <h1>
SLOTS: <%= @training.left_slots %>
      </h1>
    </section>

    <center>
    <%= render 'bookings/booking_form' if logged_in? %>
    <%= render 'bookings/index_bookings' if logged_in? %>
    </center>

预订表格视图：

<%= form_for(@training) do |f| %>

<% if f.object.errors.any? %>
  <% f.object.errors.full_messages.each do |full_message| %>
    <p>
      <%= full_message %>
    </p>
  <% end %>
<% end %>    
<% unless current_user?(@user) %>
          <% if current_user.not_booked?(@training) %>
          <%= link_to "Book", new_training_booking_path(@training), class: "btn btn-primary" %>
          <% else %>
            <% @bookings.each do |booking| %>
        <%= link_to "Unbook", training_booking_path(booking.training, booking), method: :delete, data: { confirm: 'Are you certain you want to delete this?' }, class: "btn btn-primary" %>
        <% end %>
        <% end %>
    <% end %>
      <% end %>

新预订视图：

<h1>Book confirmation</h1>

<div class="row">
  <div class="col-md-6 col-md-offset-3">
    <%= form_for ([@training, @booking]) do |f| %>
      <%= f.hidden_field :user_id, value: current_user.id %>
      <%= f.hidden_field :training_id, value: "" %>
      <%= f.submit "Confirm booking", class: "btn btn-primary" %>
    <% end %>

---

看起来add方法的实现在Rails 5中有所改变

请试一试

def training_not_full?
  errors.add(:training, :full, message: "Full training. Try another hour") unless training.can_book?
end

而不是

def training_not_full?
  errors.add(:training, "Full training. Try another hour") unless training.can_book?
end

请更改新的.html.erb表单：

<%= form_for ([@training, @booking]) do |f| %>
  <% if f.object.errors.any? %>
    <% f.object.errors.full_messages.each do |full_message| %>
      <p>
        <%= full_message %>
      </p>
    <% end %>
  <% end %>
  <%= f.hidden_field :user_id, value: current_user.id %>
  <%= f.hidden_field :training_id, value: "" %>
  <%= f.submit "Confirmar reservacion", class: "btn btn-primary" %>
<% end %>

---

它现在向我显示了这个错误：未定义的方法'except'用于完整训练。再试试一个小时：你是什么意思？执行官。请求参数：{utf8=>✓, 真实性令牌=>sCV7T3akprwsTvH1FO/X8powg7xFzO9yS/D7PLGSNCSEZQFOCCMXTRMF5KXXQFQEGYKJDUM1QRDOJWDM7ZKNRUQ==，预订=>{user\u id=>2，training\u id=>}，commit=>Confirmar reservacion，training\u id=>1}请查看我修改后的答案，我不得不添加消息：现在它没有给我任何错误，但仍然没有显示与以前一样的消息。没有像flash这样的方法可以让我显示消息？你能分享你的视图文件吗？你可以随时使用rails脚手架作为参考。