如何在Ruby on Rails模型中进行条件验证？

Question

I have a study that can have participants . I have a simple_form where the user can add participants. It looks a bit like a table:

name | company | email OR mobile | timezone
name | company | email OR mobile | timezone
name | company | email OR mobile | timezone

By default, the screen has three fieldset rows, and the user can add more rows if needed. Each row is one participant.

I would like my participant model to validate only the rows that have been filled out, and ignore rows that are blank because even though we are showing three by default to the user, not all three are required fields.

Here's the relevant portion of app/models/participants.rb .

class Participant < ApplicationRecord
  belongs_to :study

  validates :name, presence: true
  validates :company, presence: true
  validates :time_zone, presence: true

  if :channel == 'sms'
    validates :mobile_number, presence: true
  elsif :channel == 'email'
    validates :email, presence: true
  end
end

In participants_controller.rb I have:

def index
  3.times { @study.participants.build } if @study.participants.length.zero?
end

The problem is that I get an error because simple_form thinks that all three fields are required, and not just the first row.

Answer 1

Rails' validators accept conditions:

validates :mobile_number, presence: true, if: Proc.new { |p| p.study.channel == 'sms' }
validates :email,         presence: true, if: Proc.new { |p| p.study.channel == 'email' }

Answer 2

By default all inputs are required. When the form object includes ActiveModel::Validations (which, for example, happens with Active Record models), fields are required only when there is presence validation. Otherwise, Simple Form will mark fields as optional. For performance reasons, this detection is skipped on validations that make use of conditional options, such as :if and :unless.

And of course, the required property of any input can be overwritten as needed:

<%= simple_form_for @user do |f| %>
  <%= f.input :name, required: false %>
  <%= f.input :username %>
  <%= f.input :password %>
  <%= f.button :submit %>
<% end %>

Try to put all the inputs as required: false . That should allow skip simple_form validations and the data came into the controller and the model can be filtered or/and validated and every other things you want to do before persist.

In the model class you can use several ways of validations for example:

you also can use the :if and :unless options with a symbol corresponding to the name of a method that will get called right before validation happens. This is the most commonly used option.

for example

class Participant < ApplicationRecord
   belongs_to :study

   validates :name, presence: true
   validates :company, presence: true
   validates :time_zone, presence: true
   validates :mobile_number, presence: true if: :channel_is_sms? 
   validates :email, presence: true if: :channel_is_email? 

  def channel_is_sms?
    channel == "sms"
  end

  def channel_is_email?
    channel == "email"
  end
end

or also you can use custom validator where you do all that you need validate. for example

class MyValidator < ActiveModel::Validator
  def validate(record)
    unless record.channel == 'sms'
      ...
      ...  actions here
      ...
    end
  end
end

class Person
  include ActiveModel::Validations
  validates_with MyValidator
end