How to update only part of attributes, not all, in rails - ruby-on-rails

Question

I have an edit form for updating some attributes. But it tryes to edit all attributes, and cause of this I have validation error.
My form (edit view)
#person_info.fl_l
- if #user.errors.any?
.error_explanation
%h2 Form is invalid
%ul
-for message in #user.errors.full_messages
%li= message
=form_for #user do |f|
%p
Birthday:
%br
= f.date_select(:birthday,:start_year => 1940)
%p
Name:
%br
= f.text_field :name, :value=>#user.name
%p
Surname:
%br
= f.text_field :surname, :value=>#user.surname
%p
Nickname:
%br
= f.text_field :nickname, :value=>#user.surname
%p
About Myself:
%br
= f.text_area :about_myself, :value=>#user.about_myself
%p
= f.submit "Update"
My update and edit actions:
def edit
#user = User.find(params[:id])
end
def update
#user = User.find(params[:id])
if #user.update_attributes(params[:user])
redirect_to #user
else
render 'edit'
end
end
When I submit the form, it outputs validation errors like: "Password can't be blank"
So, how to update only part of attributes, not all? I dont want to update password in my case.
My user model
class User < ActiveRecord::Base
has_many :posts
has_many :sent_messages, :class_name => "Message", :foreign_key => "sender_id"
has_many :received_messages, :class_name => "Message", :foreign_key => "receiver_id"
attr_accessible :name, :email, :password, :password_confirmation
has_secure_password
email_regex = /\A[\w+\-.]+#[a-z\d\-.]+\.[a-z]+\z/i
validates :name, :presence => true,
:length => {:maximum => 50}
validates :email, :presence => true,
:format => {:with => email_regex},
:uniqueness => {:case_sensitive => false}
validates :password, :presence => true,
:confirmation => true,
:length => {:within => 6..40}
before_create { generate_token(:auth_token) }
def send_password_reset
generate_token(:password_reset_token)
self.password_reset_sent_at = Time.zone.now
save!
UserMailer.password_reset(self).deliver
end
def generate_token(column)
begin
self[column] = SecureRandom.urlsafe_base64
end while User.exists?(column => self[column])
end
end

Answer 1

Remove it from the params hash
params.delete(:password)
Or build your own hash to send to update.

Answer 2

Checkout Authentication in Rails 3.1 to smoothen out your authentication. it takes out a lot of code from your model.
Then, I noticed that: if a field is hidden from the form for any reason, rails does not pass this in the params hash for an update. So you can play with hiding fields in a form. This is how I solve mine.

Answer 3

I fixed this issue by appending
,:on => :create
to my validates_presence_of and validates_length_of lines.

Answer 4

I believe your model is invalid in its current state ... you're not sending in the password, so Rails is not touching that attribute.
In rails console, test:
user = User.find(whatever_the_id_is)
puts user.valid?
puts user.errors.inspect
My hypothesis is that it is invalid --- due to a missing password.

Answer 5

I have solved this in the User password validation like so:
validates :password, :presence => true,
:confirmation => true,
:if => :password # only validate if password changed!