如何在Rails模型和form_for中使用自定义函数？

Question

I am trying to use a model altered to support bcrypt password, like so

require 'bcrypt'
class User < ActiveRecord::Base
  # users.password_hash in the database is a :string
  include BCrypt

  def password
    @password ||= Password.new(password_hash)
  end

  def password=(new_password)
    @password = Password.create(new_password)
    self.password_hash = @password
  end
end

I added this in AFTER the scaffolding, hoping that the password and password= was enough to keep it going, using this, However it is not working, the form_for() etc wont work and I get the error:

ActionView::Template::Error (invalid hash):
2012-06-07T12:45:20+00:00 app[web.1]:     17:   </div>
2012-06-07T12:45:20+00:00 app[web.1]:     18:   <div class="field">
2012-06-07T12:45:20+00:00 app[web.1]:     19:     <%= f.label :password %><br />
2012-06-07T12:45:20+00:00 app[web.1]:     20:     <%= f.text_field :password %>
2012-06-07T12:45:20+00:00 app[web.1]:     21:   </div>
2012-06-07T12:45:20+00:00 app[web.1]:     22:   <div class="field">
2012-06-07T12:45:20+00:00 app[web.1]:     23:     <%= f.label :email %><br />

Does anyone know how I can make this work, I am new to Rails

This is On the New Function Full backtrace as requested:

2012-06-12T18:23:57+00:00 app[web.1]: ActionView::Template::Error (invalid hash):
2012-06-12T18:23:57+00:00 app[web.1]:     19:     <%= f.label :password %><br />
2012-06-12T18:23:57+00:00 app[web.1]:     18:   <div class="field">
2012-06-12T18:23:57+00:00 app[web.1]:     17:   </div>
2012-06-12T18:23:57+00:00 app[web.1]:     20:     <%= f.text_field :password %>
2012-06-12T18:23:57+00:00 app[web.1]:     22:   <div class="field">
2012-06-12T18:23:57+00:00 app[web.1]:     23:     <%= f.label :email %><br />
2012-06-12T18:23:57+00:00 app[web.1]:   app/models/user.rb:19:in `new'
2012-06-12T18:23:57+00:00 app[web.1]:     21:   </div>
2012-06-12T18:23:57+00:00 app[web.1]:   app/models/user.rb:19:in `password'
2012-06-12T18:23:57+00:00 app[web.1]:   app/views/users/_form.html.erb:20:in `block in _app_views_users__form_html_erb__2064609863987267967_31546180'
2012-06-12T18:23:57+00:00 app[web.1]:   app/views/users/_form.html.erb:1:in `_app_views_users__form_html_erb__2064609863987267967_31546180'
2012-06-12T18:23:57+00:00 app[web.1]:   app/views/users/new.html.erb:3:in `_app_views_users_new_html_erb___1991359801167056023_31763940'
2012-06-12T18:23:57+00:00 app[web.1]:   app/controllers/users_controller.rb:251:in `new'

Answer 1

The exception message "invalid hash" indicates that your view is working just fine, but User#password fails for whatever reason. Perhaps user doesn't have a password_hash defined (ie, it is nil, "", or some other invalid value), causing Password.new to error out?

Looking at your backtrace seems to reinforce this:

2012-06-12T18:23:57+00:00 app[web.1]:   app/models/user.rb:19:in `new'
2012-06-12T18:23:57+00:00 app[web.1]:   app/models/user.rb:19:in `password'.

The error occurs in user.rb when calling new inside your password method. Thus I am guessing line #19 is

@password ||= Password.new(password_hash)

So it looks like Password.new does not like the value of password_hash for some reason. Exactly why, I can only guess at.

• What exactly is Password ?
• What is the value of password_hash ?