```ruby
if Spree.user_class
  Spree.user_class.class_eval do
    has_and_belongs_to_many :roles, :class_name => "Spree::Role", :foreign_key => :user_id, :join_table_name => "spree_roles_users"
  end
end
```

Use join_table, not join_table name in user decorator
user
```ruby
if Spree.user_class
  Spree.user_class.class_eval do
    has_and_belongs_to_many :roles, :class_name => "Spree::Role", :foreign_key => :user_id, :join_table => "spree_roles_users"
  end
end
```
assistant