Issue with BlackboardVariable.ObjectVariable Null Comparison in Behavior Package 1.0.2

Unity Engine
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1

I’ve encountered a strange issue when working with the Behavior package version 1.0.2. Specifically, I’m trying to check whether a BlackboardVariable.ObjectVariable is null. However, a direct comparison to null returns false, which is unexpected.

For context, when I run:

Debug.Log(BlackboardVariable.ObjectValue);

It logs null as expected, but if I try:

if (BlackboardVariable.ObjectValue == null)
{
    // Never enters this block
}

The comparison fails. After some trial and error, I found that the only way I can reliably check for null is by doing the following:


if (BlackboardVariable.ObjectValue.ToString() == "null")
{
    // This works
}

For context, I was trying to write simple null checking condition:

public partial class IsNullCondition : Condition
{
    [SerializeReference] 
    public BlackboardVariable Variable;

    public override bool IsTrue()
    {
        return Variable.ObjectValue == null;
    }
}

This feels like an odd workaround, and I’m not sure why the direct comparison doesn’t behave as expected. Has anyone encountered a similar issue, or does anyone have insights into why this is happening? Any suggestions for a cleaner approach would be greatly appreciated.

1 Like
2

I had the same problem. I took a look at some internal actions implementations and they suddenly started using ReferenceEquals(Agent?.Value, null) for these checks.

I’ve rewritten my code do to so and it never bothered me again.

3

Yes it’s working and it’s definitely better solution than mine, but it’s still a bit counter intuitive to check for null this way.

1 Like