javascript - Nested_form_fields 在验证失败时显示现有的 has_many 嵌套字段

Question

我正在使用nested_form_fields gem 。我有以下关联，允许联系人与多个团队关联:

#models/contact.rb
class Contact < ActiveRecord::Base
  has_many :contacts_teams
  has_many :teams, through: :contacts

  accepts_nested_attributes_for :contacts_teams, allow_destroy: true
end

#models/contacts_team.rb
class ContactsTeam < ActiveRecord::Base
  belongs_to :contact
  belongs_to :team
end

#models/team.rb
class Team < ActiveRecord::Base
  has_many :contacts_team
  has_many :contacts, through: :contacts_teams
end

联系人始终必须至少有一个团队。我创建了一个自定义验证，当用户创建新的联系人或更新现有的联系人时，它会检查这一点。

#custom validation within models/contact.rb
class Contact < ActiveRecord::Base
  ...
  validate :at_least_one_contacts_team

  private
  def at_least_one_contacts_team
    # when creating a new contact: making sure at least one team exists
    return errors.add :base, "Must have at least one Team" unless contacts_teams.length > 0

    # when updating an existing contact: Making sure that at least one team would exist
    return errors.add :base, "Must have at least one Team" if contacts_teams.reject{|contacts_team| contacts_team._destroy == true}.empty?
  end           
end

它在大多数情况下都有效。但更新现有联系人团队时存在一种边缘情况。在这里，我正在更新联系人，它显示他们有两个现有的关联团队:

用户单击每个团队旁边的 X 来删除它们，以便它们不再显示在页面上，然后用户单击更新以使这些更改生效:

验证正确失败，因为用户尝试删除所有关联的团队。它正确显示验证错误消息:

但是，问题是表单不会重新显示现有的关联团队!这些关联尚未删除，因此它们仍应显示:

更新现有联系人时验证失败后如何显示现有团队关联？

我尝试删除所有 _destroy 标志，希望通过这样做，那些关联的团队能够显示出来。不幸的是它没有达到目的:

# block run when update validation fails
else
  params[:contact][:contacts_teams_attributes].each do |k,v|
    v.delete_if{|k,v| k == "_destroy" && v == "1"}
  end
  render :edit
end

我认为该页面正在记住之前运行的nested_form_fields' javascript。因此它会记住团队被标记为要删除，因此不会渲染它们。我不知道如何重置 javascript，除非执行重定向，在这种情况下，所有验证错误将不再显示。

提前致谢!

Answer 1

这就是答案。我更改了 Contact 模型中自定义验证的名称，以便错误消息有意义:

class Contact < ActiveRecord::Base

  accepts_nested_attributes_for :contacts_teams, allow_destroy: true
  validate :at_least_one_contacts_team

  private

  def at_least_one_contacts_team
    return errors.add :A_Team, "must be present" unless contacts_teams.length > 0
    return errors.add :A_Team, "must be present" if contacts_teams.reject{|contacts_team| contacts_team._destroy == true}.empty?
  end
end

然后在 ContactsController 的 update 操作中:

def update
  authorize @contact
  if @contact.update(contact_params)
    redirect_to(some_path), success: 'Updated Successfully.'
  else
    # This next line is what makes it work as expected for that edge case
    @contact.contacts_teams.reload if @contact.errors.keys.include?(:A_Team)
    render :edit
  end
end