Rails中的模型4在不包含它们时验证可选关联(Model in Rails 4 validating optional associations when they are not included)

 我在Rails应用程序中有一个嵌套表单，用于事件模型，允许用户在事件重现时指定Recurrence（另一个模型）的字段。 在创建事件时一切正常，但是当事件不再发生时（因此不想保存关系），它会在更新事件时给出错误。 我设置了重复设置来验证字段“频率”是否存在。 当没有重复时，此字段留空，但表单仍然会回来并说频率需要在那里。 帮帮我？ 
 
class Event < ActiveRecord::Base
  has_one :recurrence
  accepts_nested_attributes_for :recurrence
end

class Recurrence < ActiveRecord::Base
  belongs_to :event
  validates :frequency, :presence => true
end
 
 来自事件控制器 
 
def event_params
  params.require(:event).permit(
    :name, :start, :duration, :unit, :location, :description, :major,
    recurrence_attributes: [ :frequency, :end ])
end

def update
  @event = Event.find(params[:id])

  if @event.recurrence && !params.has_key?(:has_recurrence)
    @event.recurrence.destroy 
  end

  if @event.update(event_params)
    redirect_to event_path(@event)
  else
    render 'edit'
  end
end
 
 您将注意到它正在检查是否存在名为“has_recurrence”的参数 - 这是我在模型外部的表单中的复选框标记，用于确定是否应为事件保存重复。 如果用户选中该框，表单将尝试保存重复，但如果他们不选中该框，表单将不会保存重复（至少这是个想法）。 
 
 问题是当我提交表单来编辑事件时，当事件没有重复出现并且未检查has_recurrence框时，它仍然会尝试验证重复发生并给我一个验证错误： 
 
Recurrence frequency can't be blank
 
 更新我已根据以下答案更新了我的重复模型以有条件地验证： 
 
class Recurrence < ActiveRecord::Base
  belongs_to :event

  validates :frequency, :presence => true, :if => :has_recurrence

  def has_recurrence=( yesorno=false )
    @has_recurrence = yesorno
  end

  def has_recurrence
    @has_recurrence ||= false
  end
end
 
 我的事件控制器中的更新如下...... 
 
def update

  @event = Event.find(params[:id])

  if @event.recurrence && !@has_recurrence 
    @event.recurrence.destroy
  end

  if @event.update(event_params)
    redirect_to event_path(@event)
  else
    flash[:notice] = @event.errors
    render 'edit'
  end
end
 
 并且视图包含以下内容以检查是否存在重复： 
 
<div class="form-group">
  <%= check_box_tag "has_recurrence", nil, false %> Is this a recurring event? (must check to save recurrence)
</div>
<%= f.fields_for :recurrence do |builder| %>
  <%= render 'recurrence_fields', f: builder %>
<% end %>
 
 现在，当没有检查重复时我没有得到验证错误，但是重复发生是保存到数据库（所有内容都是空白但是event_id） 

I have a nested form in my Rails app for an Events model that allows the user to specify fields for Recurrence (another model) when the event recurs. Everything is working fine on creating the event, but it's giving me errors on updating the event when the event does not recur (and therefore does not want to save the relationship). I have recurrence set up to validate that the field "frequency" is present. When there is no recurrence, this field is left blank, but the form still kicks back and says that frequency needs to be there. Help?
 
class Event < ActiveRecord::Base
  has_one :recurrence
  accepts_nested_attributes_for :recurrence
end

class Recurrence < ActiveRecord::Base
  belongs_to :event
  validates :frequency, :presence => true
end
 
from Events controller
 
def event_params
  params.require(:event).permit(
    :name, :start, :duration, :unit, :location, :description, :major,
    recurrence_attributes: [ :frequency, :end ])
end

def update
  @event = Event.find(params[:id])

  if @event.recurrence && !params.has_key?(:has_recurrence)
    @event.recurrence.destroy 
  end

  if @event.update(event_params)
    redirect_to event_path(@event)
  else
    render 'edit'
  end
end
 
You will note that it is checking for the presence of a param called "has_recurrence" - This is a checkbox tag that I have in the form, outside of the model, to determine whether or not a recurrence should be saved for the event. If the user checks the box, the form will attempt to save the recurrence but if they do not check the box, the form will not save the recurrence (at least that's the idea).
 
The problem is that when I submit the form to edit an event, when the event is not recurring and the has_recurrence box is not checked, it still attempts to validate the recurrence and gives me back a validation error:
 
Recurrence frequency can't be blank
 
UPDATE I have updated my recurrence model to validate conditionally, based on the answer below:
 
class Recurrence < ActiveRecord::Base
  belongs_to :event

  validates :frequency, :presence => true, :if => :has_recurrence

  def has_recurrence=( yesorno=false )
    @has_recurrence = yesorno
  end

  def has_recurrence
    @has_recurrence ||= false
  end
end
 
And the update in my Events Controller is as follows...
 
def update

  @event = Event.find(params[:id])

  if @event.recurrence && !@has_recurrence 
    @event.recurrence.destroy
  end

  if @event.update(event_params)
    redirect_to event_path(@event)
  else
    flash[:notice] = @event.errors
    render 'edit'
  end
end
 
And the view contains the following to check if there is a recurrence:
 
<div class="form-group">
  <%= check_box_tag "has_recurrence", nil, false %> Is this a recurring event? (must check to save recurrence)
</div>
<%= f.fields_for :recurrence do |builder| %>
  <%= render 'recurrence_fields', f: builder %>
<% end %>
 
And now, when recurrence is not checked I do not get a validation error, but the recurrence is saving to the database (with everything blank but the event_id)

原文：https://stackoverflow.com/questions/33737341