## Minimum requirements

| Package | Minimum version |
| --- | --- |
| composition | [0.45.0](https://github.com/wundergraph/cosmo/releases/tag/%40wundergraph%2Fcomposition%400.45.0) |
| wgc | [0.93.1](https://github.com/wundergraph/cosmo/releases/tag/wgc%400.93.1) |

## Definition

```
directive @semanticNonNull(levels: [Int!]! = [0]) on FIELD_DEFINITION
```

## Overview

Indicates that a position is semantically non null: it is only null if there is a matching error in the `errors` array. In all other cases, the position is non-null. Tools doing code generation may use this information to generate the position as non-null if field errors are handled out of band:

```
type User {
    # email is semantically non-null and can be generated as non-null by error-handling clients.
    email: String @semanticNonNull
}
```

## Using with Lists

The `levels` argument indicates what levels are semantically non null in case of lists:

```
type User {
    # friends is semantically non null
    friends: [User] @semanticNonNull # same as @semanticNonNull(levels: [0])

# every friends[k] is semantically non null
    friends: [User] @semanticNonNull(levels: [1])

# friends as well as every friends[k] is semantically non null
    friends: [User] @semanticNonNull(levels: [0, 1])
}
```

`levels` are zero indexed. Passing a negative level or a level greater than the list dimension is an error.