Class ValidateInputAttribute

Marks a field for custom validation by delegating to a named instance method on the same object, enforced at runtime by ValidateObject(object).

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

Use this attribute when the built-in NotNullAttribute and NotEmptyAttribute constraints are insufficient - for example, to validate numeric ranges, cross-field dependencies, or any domain-specific invariant that requires bespoke logic.

The validation method must satisfy all of the following requirements:

  • Defined as an instance method on the same class that declares the annotated field (or a base class thereof, discovered through reflection with BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic).
  • Accepts exactly one parameter whose type is compatible with the field's type. The field value is passed directly; no type coercion is performed.
  • Returns bool - true means the value is valid; false causes a ValidationException to be thrown.

If any of these conditions are violated, AttributeValidator throws a descriptive ValidationException rather than silently skipping the check.

It is strongly recommended to reference the method name via nameof() rather than a hard-coded string literal. This ensures compile-time safety and IDE rename support, guarding against silent failures at runtime when a method is renamed without updating the attribute argument.

If the validator method itself throws an exception during invocation, AttributeValidator wraps it in a ValidationException and re-throws, preserving the inner message for diagnosis. 

public class GameSettings : MonoBehaviour
{
    [ValidateInput(nameof(ValidatePlayerCount), "Player count must be between 1 and 4.")]
    [SerializeField] private int _playerCount = 1;

[ValidateInput(nameof(ValidateVolume))]
[SerializeField] private float _volume = 1f;


private void Awake()
{
    /* Throws ValidationException if _playerCount or _volume fail their checks */
    AttributeValidator.ValidateObject(this);
}


private bool ValidatePlayerCount(int count)
{
    return count >= 1 && count <= 4;
}


private bool ValidateVolume(float volume)
{
    return volume >= 0f && volume <= 1f;
}



}

Constructors

ValidateInputAttribute(string)

Initializes a new instance of ValidateInputAttribute with the name of the custom validation method and a default auto-generated error message.

Declaration
public ValidateInputAttribute(string validatorMethod)
Parameters
Type Name Description
string validatorMethod

The name of the instance method on the owning class that performs the validation. Must not be null or empty. Prefer using nameof(YourMethod) for compile-time safety and IDE rename support.
Remarks

When the decorated field fails validation, the thrown ValidationException will carry the auto-generated message "Field '{fieldName}' failed validation.". To supply a context-specific message use the two-parameter overload.

Exceptions
Type Condition
ArgumentNullException

Thrown immediately at attribute construction if validatorMethod is null or an empty string. This provides early feedback rather than a delayed failure at validation time.

ValidateInputAttribute(string, string)

Initializes a new instance of ValidateInputAttribute with the name of the custom validation method and a developer-supplied error message.

Declaration
public ValidateInputAttribute(string validatorMethod, string errorMessage)
Parameters
Type Name Description
string validatorMethod

The name of the instance method on the owning class that performs the validation. Must not be null or empty. Prefer using nameof(YourMethod) for compile-time safety and IDE rename support.
string errorMessage

The human-readable message to include in the thrown ValidationException when the validator method returns false. Should describe the expected range or condition clearly so the developer can act on it immediately. Pass null or use the single-argument 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.

Exceptions
Type Condition
ArgumentNullException

Thrown immediately at attribute construction if validatorMethod is null or an empty string.

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 no custom message was provided. When null, AttributeValidator generates a default message of the form "Field '{fieldName}' failed validation." using the actual C# field name.

ValidatorMethod

Gets the name of the instance method on the owning class that performs the custom validation logic for the decorated field.

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

The method name as a string, exactly as it must appear through reflection. Always non-null and non-empty - the constructors enforce this invariant. The method must have the signature bool MethodName(FieldType value). Use nameof() when assigning this value to benefit from compile-time rename safety.

Extension Methods

See Also