Having more than one collider in a GameObject?

The way I got around this was to use the layers system. If you put the one collider on a gameobject then put the second on a child of the game object you can set the layer on the child to something like IgnoreRaycast which will make it invisible to the physics engine. Which is really useful in certain aspects. Like mmmPies problem, you could use the collider that you put in the IgnoreRaycast layer as range. So you'd make it a sphere in your script you use a collision between that collider and the player to pick up the item. Granted mmmPies found his own solution but when you pickup script relies on colliders this works.

Found an answer to this here. The answer was leveraging the type of the colliders on the gameobject to determine what to do:

 void OnCollisionEnter2D(Collision2D collision)
 {
     if (collision.collider.GetType() == typeof(BoxCollider2D))
     {
         // do stuff only for the box collider
     }
     else if (collision.collider.GetType() == typeof(CircleCollider2D))
     {
         // do stuff only for the circle collider
     }
 }

or using an array index, such as var collider1 = GetComponents<BoxCollider>()[0];

Bumping this because I came up with a simple solution. I wanted to fire an arrow and have it stick in whatever it hit (so it needed a trigger collider to do that) and I gave it box collider so it didn't fall through the terrain.

Also wanted a 5 meter radius collider so I could either pickup automatically or display an icon to give the choice to pick up the arrow on the floor. Came to this post hoping for a solution to multiple colliders in one gameobject, then I realised I'd seen something similar in the Burgzerg treasure chest tutorial. So I used that:

 public bool AlwaysPickup;        // If yes picks up on collision (small item like arrows). If no displays pickup icon.

 private Transform _itemTransform;
 private GameObject _player;
 private float _inRange;
 private bool _triggered;
 private bool _released;

 void Awake()
 {
     _itemTransform = transform;
     _player = GameObject.FindGameObjectWithTag("Player");
     _inRange = 5f;
     _triggered = false;
 }

 void Update()
 {
     if(_player == null)            // Probably wasteful. Consider changing the order of the scripts so the Player is available
     {
         _player = GameObject.FindGameObjectWithTag("Player");
     }

     if(Vector3.Distance(_itemTransform.position, _player.transform.position) < _inRange)
     {
         if(!_triggered)
             Trigger ();
     }
     else if (!_released)
         Released();
 }

 private void Released()
 {
     _triggered = false;
     _released = true;

     Debug.Log ("Exited range at: " + Time.time);

     if(!AlwaysPickup)
     {
         Debug.Log ("Remove display pickup icon here");
     }
 }

 private void Trigger()
 {
     _triggered = true;
     _released = false;

     Debug.Log ("Entered range at: " + Time.time);

     if(AlwaysPickup)
     {
         Debug.Log ("I should handle picking up the item here");
     }
     else
     {
         Debug.Log ("Put display icon here");
     }
 }

You can attach multiple empty gameObjects with Coliders to your main gameObject, and attach to them simple script, which triggers Actions, which can be subscribed by parent gameObject.

Each child gameObject with collider will have the same script:

 {
 
     using UnityEngine;
     using System;
 
     public class Collision2D_Proxy : MonoBehaviour
     {
 
     public Action<Collision2D> OnCollisionEnter2D_Action;
     public Action<Collision2D> OnCollisionStay2D_Action;
     public Action<Collision2D> OnCollisionExit2D_Action;
 
     private void OnCollisionEnter2D(Collision2D collision)
     {
         OnCollisionEnter2D_Action?.Invoke(collision);
     }
 
     private void OnCollisionStay2D(Collision2D collision)
     {
         OnCollisionStay2D_Action?.Invoke(collision);
     }
 
     private void OnCollisionExit2D(Collision2D collision)
     {
         OnCollisionExit2D_Action?.Invoke(collision);
     }
 
     // etc ...
 }
 
 

Parent gameObject needs just to subscribe required events:

 public class CharacterBehaviour : MonoBehaviour
 {
 
     private Collision2D_Proxy firstCollider;
     private Collision2D_Proxy secondCollider;
 
 
     void Start()
     {
         // subscribe collision events
 
         firstCollider = transform.Find("FirstChildGameObjectName").GetComponent<Collision2D_Proxy>();
         firstCollider.OnCollisionEnter2D_Action += firstColider_OnCollisionEnter2D;
 
         secondCollider = transform.Find("SecondChildGameObjectName").GetComponent<Collision2D_Proxy>();
         secondCollider.OnCollisionExit2D_Action += secondColider_OnCollisionExit2D;
     }
 
     private void firstColider_OnCollisionEnter2D(Collision2D collision)
     {
         print("first collider OnCollisionEnter2D collision" );        
     }
 
      private void secondColider_OnCollisionExit2D(Collision2D collision)
     {
         print("second collider OnCollisionExit2D collision" );        
 }