has_one association not adding methods to belongs_to class - ruby-on-rails

Question

I have two tables User and UserToken. User has_one: token and UserToken belongs_to :user. I was under the impression this would add UserToken#User method to the UserToken class. However, I am getting:
undefined method 'user' for '#' with the
following 'UserToken.where(user_id: 1).user
Do I not understand the association correctly or have I not set it up right?
UsersController:
def get
user = UserToken.where(user_id: 1).user
render json: user.to_json
end
User Model:
class User < ApplicationRecord
has_one :user_token
end
UserToken Model:
class UserToken < ApplicationRecord
belongs_to :user
end
Migration:
def change
create_table :users do |t|
# This id comes from Auth0
t.datetime :date
t.timestamp :updated_at
t.timestamp :created_at
end
create_table :user_tokens do |t|
t.belongs_to :user
# This comes from plaid when a user signs in
t.string :token
t.timestamp :updated_at
t.timestamp :created_at
end
end
Schema:
ActiveRecord::Schema.define(version: 2019_09_19_004350) do
create_table "user_tokens", force: :cascade do |t|
t.bigint "user_id"
t.string "token"
t.datetime "updated_at"
t.datetime "created_at"
t.index ["user_id"], name: "index_user_tokens_on_user_id"
end
create_table "users", force: :cascade do |t|
t.datetime "date"
t.datetime "updated_at"
t.datetime "created_at"
end
end

Answer 1

What you want is:
UserToken.where(user_id: 1).first.user
or better yet:
UserToken.find_by(user_id: 1).user
You're getting the "undefined method" error because #where returns an ActiveRecord::Relation and an ActiveRecord Relation has no #user method.
UserToken.where(user_id: 1).class.name
#=> "ActiveRecord::Relation"
UserToken.where(user_id: 1).first.class.name
#=> "UserToken"