NoMethodError: undefined method `<=>' for :zip:Symbol

rubyonrails-talk
1

Long time programmer, but I just started learning RoR last week. I am going through some examples in the book "Ruby on Rails: Up and Running".

The example I am on had me add a table to the database that looks like so: CREATE TABLE people (   `id` int(11) NOT NULL auto_increment,   `type` varchar(20) default NULL,   `name` varchar(20) default NULL,   `email` varchar(30) default NULL,   `street_address` varchar(30) default NULL,   `city` varchar(30) default NULL,   `state` varchar(20) default NULL,   `zip` int(5) default NULL,   `camera` varchar(20) default NULL,   PRIMARY KEY (`id`) )

In addition, I created the following two classes:

class Person < ActiveRecord::Base   composed_of :address, :class_name => "Address",               :mapping => [[:street_address, :street_address],                            [:city, :city],                            [:state, :state],                            [:zip, :zip]] end

class Address   def initialize(street_address, city, state, zip)     @street_address = street_address     @city = city     @state = state     @zip = zip   end

  attr_reader :street_address, :city, :state, :zip end

Finally, it had me run the following commands in Console:

elvis.name=Person.new

elvis.name=Person.new NameError: undefined local variable or method `elvis' for #<Object: 0x284f9e8>   from (irb):1

elvis=Person.new

elvis=Person.new => #<Person id: nil, type: nil, name: nil, email: nil, street_address: nil, city: nil, state: nil, zip: nil, camera: nil>

elvis.name="Elvis Presley"

elvis.name="Elvis Presley" => "Elvis Presley"

elvis.email="elvis@graceland.com"

elvis.email="elvis@graceland.com" => "elvis@graceland.com"

address=Address.new("3734 Elvis Presley Blvd", "Memphis", "Tennessee", 38118)

address=Address.new("3734 Elvis Presley Blvd", "Memphis", "Tennessee", 38118) => #<Address:0x3f3ce94 @street_address="3734 Elvis Presley Blvd", @zip=38118, @state="Tennessee", @city="Memphis">

elvis.address=address

elvis.address=address => #<Address:0x3f3ce94 @street_address="3734 Elvis Presley Blvd", @zip=38118, @state="Tennessee", @city="Memphis">

elvis.save

elvis.save

However, when I ran the latter-most command, "elvis.save" I received the following (abbreviated) error:

NoMethodError: undefined method `<=>' for :zip:Symbol   from C:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/ active_record/base.rb:2177:in `sort'   from C:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/ active_record/base.rb:2177:in `attribute_names'   from C:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/ active_record/base.rb:2458:in `clone_attributes' ...

Why is the method '<=>' being attempted on the zip field?

2

In addition, I created the following two classes:

class Person < ActiveRecord::Base composed_of :address, :class_name => "Address",              :mapping => [[:street_address, :street_address],                           [:city, :city],                           [:state, :state],                           [:zip, :zip]] end

However, when I ran the latter-most command, "elvis.save" I received the following (abbreviated) error:

NoMethodError: undefined method `<=>' for :zip:Symbol   from C:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/ active_record/base.rb:2177:in `sort'   from C:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/ active_record/base.rb:2177:in `attribute_names'   from C:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/ active_record/base.rb:2458:in `clone_attributes' ...

Why is the method '<=>' being attempted on the zip field?

it's not calling <=> on the zip field itself but on the mapping you've supplied, which is expected to contain strings

:mapping => [%w(street_address street_address),                           %w(city city),                           %w(state state),                           %w(zip zip)]

Should do the trick

Fred