II'm using Rails 5. I want to search for a model based on a user\_id field. My table looks like this

```
cindex=# \d user_notifications;
                               Table "public.user_notifications"
       Column       |  Type   |                            Modifiers
--------------------+---------+-----------------------------------------------------------------
 id                 | integer | not null default nextval('user_notifications_id_seq'::regclass)
 user_id            | integer |
 crypto_currency_id | integer |
 price              | integer | not null
 buy  

          | boolean | not null

```

but when I attempt to look up a model like so

```
 @user_notification = UserNotification.find_by_user(current_user)

```

I get the error

```
undefined method `find_by_user' for UserNotification:Class

```

What's the simple (Rails) way to look up my field?