Using a named scope - ruby-on-rails

Question

I"m trying to use a named scope to set my users carrier but keep getting this error
undefined method `target' for #<ActiveRecord::Relation:0x5ee3e40>
app/models/user.rb:19:in `set_carrier'
app/controllers/users_controller.rb:49:in `block in create'
app/controllers/users_controller.rb:48:in `create'
<div class= "field">
<%= f.label :carrier %><br>
<%= f.collection_select(:carrier_name, Carrier.find(:all) ,:name, :name) %>
</div>
user.rb
class User < ActiveRecord::Base
acts_as_authentic
after_create :set_sub
after_create :set_universal
after_create :set_carrier
def set_sub
#self.roles << "subscriber"
self.roles_mask = 4
end
def set_universal
self.channels << Channel.find(1)
end
def set_carrier
#carrier = Carrier.with_name(self.carrier_name)
self.carrier<< #carrier
end
ROLES = %w[admin moderator subscriber]
#Each user can subscribe to many channels
has_and_belongs_to_many :channels
#Each user who is a moderator can moderate many channels
#has_many :channel_mods
has_and_belongs_to_many :modifies , :class_name => "Channel"
#Each user can receive many messages
has_and_belongs_to_many :messages
#Each user belongs to a carrier
belongs_to :carrier
#Filter users by role(s)
named_scope :with_role, lambda { |role| {:conditions => "roles_mask & #{2**ROLES.index(role.to_s)} > 0 "} }
def roles
ROLES.reject { |r| ((roles_mask || 0) & 2**ROLES.index(r)).zero? }
end
def roles=(roles)
self.roles_mask = (roles & ROLES).map { |r| 2**ROLES.index(r) }.sum
end
def role_symbols
roles.map do |role|
role.underscore.to_sym # NOT role.name.underscore.to_sym (role is a string)
end
end
end
carrier.rb
class Carrier < ActiveRecord::Base
has_many :users
named_scope :with_name, lambda {|name| {:conditions => {:name => name}}}
end
user controller
class UsersController < ApplicationController
filter_resource_access
# GET /users
# GET /users.xml
def index
#users = User.all
respond_to do |format|
format.html # index.html.erb
format.xml { render :xml => #users }
end
end
# GET /users/1
# GET /users/1.xml
def show
##user = User.find(params[:id])
respond_to do |format|
format.html # show.html.erb
format.xml { render :xml => #user }
end
end
# GET /users/new
# GET /users/new.xml
def new
##user = User.new
#carriers = Carrier.find(:all)
respond_to do |format|
format.html # new.html.erb
format.xml { render :xml => #user }
end
end
# GET /users/1/edit
def edit
##user = User.find(params[:id])
end
def create
##user = User.new(params[:user])
##user.channels << Channel.find(1)
respond_to do |format|
if #user.save
format.html { redirect_to(:channels, :notice => 'Registration successfully.') }
format.xml { render :xml => #user, :status => :created, :location => #user }
else
format.html { render :action => "new" }
format.xml { render :xml => #user.errors, :status => :unprocessable_entity }
end
end
end
def profile
#user = User.find(params[:id])
end
# PUT /users/1
# PUT /users/1.xml
def update
##user = current_user
respond_to do |format|
if #user.update_attributes(params[:user])
format.html { redirect_to(#user, :notice => 'User was successfully updated.') }
format.xml { head :ok }
else
format.html { render :action => "edit" }
format.xml { render :xml => #user.errors, :status => :unprocessable_entity }
end
end
end
# DELETE /users/1
# DELETE /users/1.xml
def destroy
#user = User.find(params[:id])
#user.destroy
respond_to do |format|
format.html { redirect_to(users_url) }
format.xml { head :ok }
end
end
def delete
#user = User.find(params[:user_id])
#user.destroy
redirect_to :users
end
end

Answer 1

You might be using an array instead of a singular item. belongs_to relationships are either nil or a model.
You may have intended to do a direct assignment:
def set_carrier
self.carrier = Carrier.with_name(self.carrier_name).first
end
The << operator is used to append items to arrays, but carrier is not an array. This may trip up something deeper in Rails.

Answer 2

Just in case this helps anyone: I was getting this error message too with a model like this:
def Foo
has_many :bars
has_many :thingies, through: :bars
end
I was then doing this in the controller;
Foo.all.includes(:bars, :thingies)
and it blew up trying to go through scopes. The fix was to remove "bars" from the includes call - they will be automatically eager-loaded because "thingies" is being eager loaded.