ActiveAdmin: how to leave user password unchanged?

Devise provides an update_without_password method that you can use when updating a user if no password is entered. Using that method, you can customize the update method in your ActiveAdmin users controller.

 def update
   @user = User.find(params[:id])
   if params[:user][:password].blank?
     @user.update_without_password(params[:user])
   else
     @user.update_attributes(params[:user])
   end
   if @user.errors.blank?
     redirect_to admin_users_path, :notice => "User updated successfully."
   else
     render :edit
   end
 end

The Devise Wiki has more information about this method if your interested.

You don't really need to mess at all with Devise's registration controller, you can just ignore empty password fields inside ActiveAdmin's resource controller:

ActiveAdmin.register User do
  controller do

    def update
      model = :user

      if params[model][:password].blank?
        %w(password password_confirmation).each { |p| params[model].delete(p) }
      end

      super
    end
  end
end

You need to evaluate password and password_confirmation in the if statement, to apply the validations on "password_confirmation", eg for my case:

#app/admin/user.rb
controller do
  def update
    if params[:user][:password].blank? && params[:user][:password_confirmation].blank?
      params[:user].delete("password")
      params[:user].delete("password_confirmation")
    end
    super
  end
end


#app/model/user.rb
validates :name, :email, presence: true
validates :password, :password_confirmation, presence: true, on: :create
validates :password, confirmation: true

This allows me to validate password presence only when I create a new user and update without changing his password.

This work for me, I hope this is helpful.

I hope this is helpful.