访问嵌套属性字段的错误消息

Question

我有一个使用 simple_form gem 创建的表单，它使用嵌套属性填充 2 个模型。我想检查是否有任何错误并显示一个新块。但是，我不确定如何正确访问Booking 模型的location 属性的错误消息。

class Booking < ActiveRecord::Base
  belongs_to :customer

  attr_accessible :date_wanted, :location
end

和

class Customer < ActiveRecord::Base
  has_many :bookings
  accepts_nested_attributes_for :bookings

  attr_accessible :name, :phone, :bookings_attributes

  validates_presence_of :name, :phone
end

表单视图：

simple_form_for @customer, {:html => { :class => "form-horizontal" }} do |f|
  = f.input :name
  = f.input :phone
  = f.simple_fields_for :bookings do |b|
    = b.input :date
    = b.input :location
    - if @customer.errors[:appointments_attributes][:location]
      # insert code if any validation errors for the date field were found
  = f.button :submit

Answer 1

b是form builder的一个实例，持有booking，可以试试：

# ...
if b.object.errors[:location]
# ...