InputActionCallbackAttribute

Method attribute that marks a method as an input action handler. Specifies which input action to bind to and which phase to respond to. Used by InputActionMapBinding for reflection-based callback discovery.

Definition

Namespace: Paragon.Core.InputSystem Assembly: Paragon.dll

[AttributeUsage(AttributeTargets.Method)]
public class InputActionCallbackAttribute : Attribute

Inherits: System.Attribute

Remarks

This attribute is the declarative core of the Input System binding framework. When InputActionMapBinding.Bind() is called, reflection scans the subclass for methods bearing this attribute and wires them up to the corresponding Unity InputAction events.

The attribute also carries [MeansImplicitUse] (JetBrains annotation), which tells IDE analyzers that the marked method is used even though it has no explicit call sites — suppressing "unused method" warnings.

Quick Lookup

Goal	How
Bind to default phase (performed)	[InputActionCallback("ActionName")]
Bind to started phase	[InputActionCallback("ActionName", InputActionPhase.STARTED)]
Bind to cancelled phase	[InputActionCallback("ActionName", InputActionPhase.CANCELLED)]

Fields

ActionName

The name of the input action to bind to. Must match an action name in the target InputActionMap.

public readonly string ActionName;

InputPhase

The input action phase this handler responds to.

public readonly InputActionPhase InputPhase;

Defaults to InputActionPhase.PERFORMED.

Constructor

public InputActionCallbackAttribute(string actionName, InputActionPhase phase = InputActionPhase.PERFORMED)

Parameter	Type	Description
actionName	string	Name of the input action in the InputActionMap
phase	InputActionPhase	Phase to subscribe to. Defaults to PERFORMED.

Common Pitfalls

Methods only AttributeUsage(AttributeTargets.Method) restricts this to methods. Applying it to properties, fields, or classes will cause a compiler error.

Action name must match The ActionName string must exactly match an action in the InputActionMap. Mismatches cause NullReferenceException during binding when FindAction() returns null.

One method per (action, phase) pair Within a single InputActionMapBinding subclass, each (ActionName, InputPhase) combination must be unique. Duplicates throw a dictionary key collision during Bind().

Examples

Different phase bindings

// Fires when the action is fully performed (default)
[InputActionCallback("Attack")]
private void OnAttack() { }

// Fires when the button is first pressed
[InputActionCallback("Sprint", InputActionPhase.STARTED)]
private void OnSprintStart() { }

// Fires when the button is released
[InputActionCallback("Sprint", InputActionPhase.CANCELLED)]
private void OnSprintStop() { }

Different method signatures

// No parameters — input value is discarded
[InputActionCallback("Jump")]
private void OnJump() { }

// Typed value — auto-extracted from CallbackContext
[InputActionCallback("Move")]
private void OnMove(Vector2 direction) { }

// Full context — for advanced scenarios
[InputActionCallback("Interact")]
private void OnInteract(InputAction.CallbackContext context) { }

See Also

• InputActionMapBinding — discovers and binds methods with this attribute

• InputActionCallback — wraps the marked methods into Unity-compatible delegates

• InputActionPhase — the phase enum used by this attribute