验证表单中嵌套属性的存在 [英] Validate presence of nested attributes within a form

问题描述

我有以下关联:

#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

一个contact应该始终至少具有一个关联的团队(在contacts_teams的富连接表中指定).

A contact should always have at least one associated team (which is specified in the rich join table of contacts_teams).

如果用户尝试在没有关联团队的情况下创建联系人，则应进行验证.如果用户尝试删除联系人的所有关联团队，则应进行验证.

If the user tried to create a contact without an associated team: a validation should be thrown. If the user tries to remove all of a contact's associated teams: a validation should be thrown.

我该怎么做?

我确实查看了嵌套属性文档.我还查看了本文和本文有点过时了.

I did look at the nested attributes docs. I also looked at this article and this article which are both a bit dated.

完成操作:我正在使用nested_form_fields gem向联系人动态添加新的关联团队.这是表格中的相关部分(有效，但目前尚未验证至少一个团队与该联系人相关联):

For completion: I am using the nested_form_fields gem to dynamically add new associated teams to a contact. Here is the relevant part on the form (which works, but currently not validating that at least one team was associated to the contact):

<%= f.nested_fields_for :contacts_teams do |ff| %>
  <%= ff.remove_nested_fields_link %>
  <%= ff.label :team_id %>
  <%= ff.collection_select(:team_id, Team.all, :id, :name) %>
<% end %>
<br>
<div><%= f.add_nested_fields_link :contacts_teams, "Add Team"%></div>

因此，如果未单击添加团队"，则不会通过与团队相关的参数，因此不会创建任何contacts_team记录.但是，当单击添加团队"并选择了一个团队并提交了表单时，将通过以下参数传递类似这样的信息:

So when "Add Team" is not clicked then nothing gets passed through the params related to teams, so no contacts_team record gets created. But when "Add Team" is clicked and a team is selected and form submitted, something like this gets passed through the params:

"contacts_teams_attributes"=>{"0"=>{"team_id"=>"1"}}

推荐答案

这将进行创建和更新contact的验证:确保至少有一个关联的contacts_team.当前存在一种边缘情况，这会导致较差的用户体验. 我在此处发布了该问题.尽管在大多数情况下，这可以解决问题.

This does the validations for both creating and updating a contact: making sure there is at least one associated contacts_team. There is a current edge case which leads to a poor user experience. I posted that question here. For the most part though this does the trick.

#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

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