Class NotNullAttribute

Marks a field as requiring a non-null reference, enforced at runtime by ValidateObject(object).

Inheritance
object
Attribute
NotNullAttribute
Inherited Members
Namespace: Scylla.Core.Attributes
Assembly: ScyllaCore.dll
Syntax
[AttributeUsage(AttributeTargets.Field)]
public sealed class NotNullAttribute : Attribute
Remarks

Unlike RequiredAttribute, which surfaces a warning box in the Unity Inspector at edit-time only, NotNullAttribute is evaluated programmatically at runtime. This makes it suitable for catching missing references in builds where the Inspector is unavailable, and aligns with Scylla's fail-fast philosophy of surfacing configuration errors before any gameplay logic executes.

The validator correctly handles Unity's pseudo-null pattern. A UnityEngine.Object-derived field that has been destroyed at runtime will pass a C# null check (== null) but still fail the Unity equality operator. AttributeValidator uses the Unity equality operator for such fields, so destroyed Unity objects are correctly reported as null.

This attribute targets fields only (Field) and is picked up through reflection by ValidateObject(object). Both public and non-public (private, protected) fields are inspected.

To check for emptiness in addition to null (e.g., for strings or collections), use NotEmptyAttribute. For custom validation logic, use ValidateInputAttribute. 

public class GameManager : MonoBehaviour
{
    [NotNull]
    [SerializeField] private Camera _mainCamera;

[NotNull("AudioManager reference is required!")]
[SerializeField] private AudioManager _audioManager;

private void Awake()
{
    /* Throws ValidationException if _mainCamera or _audioManager is null */
    AttributeValidator.ValidateObject(this);
}



}

Constructors

NotNullAttribute()

Initializes a new instance of NotNullAttribute that uses the default generated error message when validation fails.

Declaration
public NotNullAttribute()
Remarks

When the decorated field is null at validation time, AttributeValidator produces the message "Field '{fieldName}' cannot be null." automatically, where fieldName is the C# name of the annotated field as returned by reflection.

NotNullAttribute(string)

Initializes a new instance of NotNullAttribute with a custom error message that is used verbatim when validation fails.

Declaration
public NotNullAttribute(string errorMessage)
Parameters
Type Name Description
string errorMessage

The human-readable message to include in the thrown ValidationException when the field value is null. Should clearly identify which field failed and what assignment is required. Pass null or omit this overload to use the auto-generated message.
Remarks

The supplied errorMessage is stored verbatim and forwarded to ValidationException without modification. There is no validation of the message string itself; passing null here is equivalent to using the parameterless constructor.

Properties

ErrorMessage

Gets the custom error message displayed when validation fails for the decorated field.

Declaration
public string ErrorMessage { get; }
Property Value
Type Description
string

A non-null string containing the developer-supplied error message, or null when the parameterless constructor was used. When null, AttributeValidator generates a default message of the form "Field '{fieldName}' cannot be null." using the actual C# field name.

Extension Methods

See Also