Using .build method to create through 1to1 association

I have a one to one relationship with a simple users model and a profiles model:

models/user

class User < ActiveRecord::Base
  authenticates_with_sorcery!

  attr_accessible :email, :password, :password_confirmation

  has_one :profile, :dependent => :destroy

  validates_presence_of :password, :on => :create
  validates :password, :confirmation => true,
          开发者_开发问答             :length       => { :within => 6..100 }

  email_regex = /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
  validates :email, :presence        => true,
                    :format          => { :with => email_regex },
                    :uniqueness      => {:case_sensitive => false},
                    :length          => { :within => 3..50 }
end

models/profile

            # == Schema Information
    #
    # Table name: profiles
    #
    #  id         :integer         not null, primary key
    #  weight     :decimal(, )
    #  created_at :datetime
    #  updated_at :datetime
    #

    class Profile < ActiveRecord::Base
      attr_accessible :weight

      belongs_to :user

    end

I am doing it this way because I would like users to be able to track weight over time as well as store other more static data like height in profiles.

However, my new and create methods don't seem to be working correctly. I on submit of the new action I get this error:

undefined method `build' for nil:NilClass

profile_controller

class ProfilesController < ApplicationController

  def new
    @profile = Profile.new if current_user
  end

  def create
    @profile = current_user.profile.build(params[:profile])
    if @profile.save
      flash[:success] = "Profile Saved"
      redirect_to root_path
    else
      render 'pages/home'
    end
  end

  def destory
  end

end

and profile view for new

<%= form_for @profile do |f| %>
    <div class="field">
        <%= f.text_field :weight %>
    </div>
    <div class="actions">
        <%= f.submit "Submit" %>
    </div>
<% end %>

Thanks in advance for any help you might be able to give. Noob here!

The build syntax for has_one association is different from has_many association. Change your code as follows:

@profile = current_user.build_profile(params[:profile])

Reference: SO Answer