# .ref

When a type references another type, it is not possible to directly query that object. The `.ref` operator enables support for such an operation. It is similar to a JOIN operation in SQL. This is used to reference other types which have their own `id` field and are first-class database objects.

## Example: User and Profile

Given the following example of a User and a Profile:

The User object has fields such as name, and ID.

```json
{
  "id" : "abcd",
  "name" : "earl1",
  "email" : "earl1@example.com"
}
```

```json
{
  "id" : "defg",
  "displayName" : "Earl 1",
  "user" : {
    "id" : "abcd",
    "name" : "earl1",
    "email" : "earl1@example.com"
  }
  "application" : { 
    "id" : "hijk",
    "name" : "EXAMPLE"
  }
}
```

It would, at a glance, make sense to attempt to query a Profile this way:

`user.id:abcd`

However, as User is a reference that will return no results. Therefore it is necessary to use the reference operator to perform the query:

`.ref.user:abcd`

This tells the query engine to execute the following:

* Identify the client is requesting a reference to another object.
* Identify the reference as the `user` field.
* Find a user with `id = "abcd"`
* Find all Profiles matching that user.