Question

Anytime I create a user and log in this exception is thrown on the redirect: Couldn't find User without an ID.

I have a has_many association like so:

class Post < ActiveRecord::Base
has_many :tags
belongs_to :user

attr_accessible :title, :description, :content, :tags_attributes

accepts_nested_attributes_for :tags, allow_destroy: true, reject_if: lambda {|attrs| attrs.all? {|key, value| value.blank?}}

end

followed by:

class User < ActiveRecord::Base

has_many :posts
attr_accessible :codename, :password, :password_confirmation

end

There is a third model ‘Tags’ which has a belongs_to post but that does not appear to be causing the problem. There is also a SessionsController with new,create, and destroy actions (code below).

The find_user method is run only on the new and create actions in the PostsController

before_filter :find_user

def find_user
 @user = User.find(params[:user_id])
end


def new
 @post = @user.posts.build(tags: Tag.new)
  respond_to do |format|
   format.html 
  end
end

def create
 @post = @user.posts.build(params[:post])
 @tags = @post.tags.build(params[:tags])
  respond_to do |format|
  if @post.save
    format.html { redirect_to @post, notice: 'Post was successfully created.' }
  else
    format.html { render action: :new }
  end
 end
end

and the User.authenticate method / SessionsController create action

def self.authenticate(codename, password)
 user = User.find_by_codename(codename)
  unless user && user.authenticate(password)
   raise "You are not who you say you are."
  end
 user
end

def create
 session[:user_id] = User.authenticate(params[:codename], params[:password]).id 
 redirect_to action: session[:intended_action], controller: session[:intended_controller], success: "You're In!"
end

Answer 1

The problem seems to be easy – you storing id of authenticated User in session object, but trying to fetch user using params[:user_id] instead of session[:user_id]