Non-null

Non-null is a wrapper type. It wraps any other type and signifies that type can’t be null.

type User {
  name: String!
}

If we select User.name in a query:

query {
  user(id: "abc") {
    name
  }
}

then we will never get this response:

{
  "data": {
    "user": {
      "name": null
    }
  }
}

These two responses are valid:

{
  "data": {
    "user": {
      "name": "Loren"
    }
  }
}

{
  "data": {
    "user": null
  }
}

When there are multiple levels of non-null, the null propagates upward. We’ll see an example of this in Chapter 4: Errors.