Rails 4 validation conditional on value of a hidden field

Question

How can I perform a validation only if the value of a hidden_field matches a specified value?

For example, I have two forms each with a separate submit button and a separate hidden_field, the value of which determines whether to run one set of validations or another.

The problem seems to be with the hidden_field check (if I replace it with just a true/false value the rest of the code works).

Model:

  validates :new_email, presence: true, length: { minimum: 1 }, on: :update, if: :email_update?
  validates :new_password, presence: true, confirmation: true, length: { minimum: 1 }, on: :update, if: :password_update?
  validates :new_password_confirmation, presence: true, on: :update, if: :password_update?
  validate :password_retype, on: :update

#  before_save :copy_values

  attr_accessor :remember_token,
                :new_email,
                :new_password,
                :existing_password,
                :update_type

  def email_update?
    update_type == "email_only"
  end

  def password_update?
    update_type == "password_only"
  end

View:

<h1>メールアドレス変更</h1>

<%= form_for(@customer) do |f| %>
  <p>
    <%= f.label :new_email, "Email" %><br>
    <%= f.email_field :new_email, placeholder: "Email" %>
  </p>
  <p>
    <%= f.label :existing_password, "パスワード" %><br>
    <%= f.password_field :existing_password, placeholder: "Password" %>
  </p>
  <p>
    <%= f.submit "変更する" %>
    <%= hidden_field :update_type, "email_only" %>
  </p>
<% end %>

<h1>パスワード変更</h1>

<%= form_for(@customer) do |f| %>
  <p>
    <%= f.label :existing_password, "現在のパスワード" %><br>
    <%= f.password_field :existing_password, placeholder: "Old Password" %>
  </p>
  <p>
    <%= f.label :new_password, "新しいパスワード" %><br>
    <%= f.password_field :new_password, placeholder: "New Password" %>
  </p>
  <p>
    <%= f.label :new_password_confirmation, "新しいパスワード（確認用）" %><br>
    <%= f.password_field :new_password_confirmation, placeholder: "Confirm New Password" %>
  </p>
  <p>
    <%= f.submit "変更する" %>
    <%= hidden_field :update_type, "password_only" %>
  </p>
<% end %>

Controller:

  def edit
    @error_messages = []
    @customer = Customer.find_by(params[:customerID])
  end

  def update
    @error_messages = []
    @customer = Customer.find_by(params[:customerID])
    if @customer.update(customer_params)
    #if @customer.update_attributes(customer_params)
      render "edit"
    else
      render "edit"
    end
  end

  private

  def customer_params
    params.require(:customer).permit( :new_email,
                                      :new_password,
                                      :new_password_confirmation,
                                      :existing_password,
                                      :update_type )
  end

Params:

--- !ruby/hash:ActionController::Parameters
utf8: "✓"
_method: patch
authenticity_token: zlYVtgQ0LuhYEpM3cRNf9QwhH8+0THluUTEGxEYprybcJrilWKHiUkJ5ypo1JnKRsbtsDTUp+o1xuRr/Pbkp2w==
customer: !ruby/hash:ActionController::Parameters
  new_email: ''
  existing_password: ''
commit: "変更する"
update_type: !ruby/hash:ActionController::Parameters
  email_only: ''
controller: customers
action: update
id: '2'

This has been stumping me for the best part of two days now. :(

Answer 1

You should do

<%= f.hidden_field :update_type, :value => "email_only or password_only" %>