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Question by Essential · Mar 27, 2012 at 09:56 AM · nullreferenceexceptionontriggerstaycomparetag

NullReferenceException using CompareTag

Can't figure out what I'm doing wrong here but it keeps coming up with a NullReferenceException error on the CompareTag line. Maybe I'm using it incorrectly? Have tried everything.

 function OnTriggerStay(other : Collider) {
     if (!other.transform.parent.CompareTag("Player")) {
         Debug.Log("something other than player");
     }
 }
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Answer by farooqaaa · Mar 27, 2012 at 10:26 AM

You're trying to access the parent of a GameObject which does not have a parent. Check if it has a parent and then compare the tag. Try this:

 function OnTriggerStay(other : Collider) 
 {
     if (other.transform.parent && !other.transform.parent.CompareTag("Player")) {
        Debug.Log("something other than player");
     }
 }
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avatar image Essential · Mar 27, 2012 at 10:25 PM 0
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Solves the error. Though now doesn't work as intended (needs to trigger for everything, not just objects with parents) — will have to investigate another method. Thanks.

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Answer by AtomicHippo · Mar 27, 2012 at 10:21 AM

I think that should be

 if (other.transform.parent.CompareTag!=("Player")) {
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avatar image AtomicHippo · Mar 27, 2012 at 10:51 AM 1
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Apologies for this answer, I somehow managed to overlook the parent reference in your code:(

avatar image Essential · Mar 27, 2012 at 11:07 AM 0
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That's okay, thanks for trying. :)

avatar image farooqaaa · Mar 27, 2012 at 12:03 PM 0
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Took back my downvote. Please check your code before posting an answer.

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Answer by Viluredfish · Mar 27, 2012 at 11:25 AM

Does your GameObject with collider, got a parent with tag player? maybe try to put to your object the tag Player not at your parent, and then, if (!other.CompareTag ("Player")) { Debug.Log("something other than player"); }

in your exemple, if an object, without parent stay in your trigger, it will cast an NullReferenceException. I think

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