Component turns null after construction | Unreal Source | Page 1

half shard Oct 21, 2024, 9:39 AM

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Hi, i have a problem where i make a movement component in the constructor of a pawn, it gets saved in the class but at begin play it is null. after looking into this issue i found that it might be an unreal bug. One solution i found was to delete the blueprint that was created from my code. This worked for me on my device but when other people try it on their device it is still broken. Is there a way to fix this without everyone im working with having to re create the blueprint?

radiant stone Oct 21, 2024, 9:40 AM

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How are you storing the pointer to the component?

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What are the specifiers in the header?

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Usually stuff like this is because the pointer to the component is allowed to be edited and is then accidentally serialised as nullptr.

half shard Oct 21, 2024, 9:41 AM

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protected:
    UPROPERTY(VisibleAnywhere, BlueprintReadWrite, Category = "Custom|Components")
    TObjectPtr<UFloatingPawnMovement> _movementComponent;

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this is how i store it in the header

radiant stone Oct 21, 2024, 9:42 AM

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For subobjects the correct UPROP is:

UPROPERTY(VisibleAnywhere, BlueprintReadOnly)
TObjecPtr<UComp> TheComp = nullptr;

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VisibleAnywhere is correct but BP-RW could be problematic

hidden geyser Oct 21, 2024, 9:42 AM

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also post creation code

radiant stone Oct 21, 2024, 9:42 AM

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The pointer should never be edited outside the ctor

half shard Oct 21, 2024, 9:42 AM

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ill try changing that

radiant stone Oct 21, 2024, 9:42 AM

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It won't repair any BP:s that have already been broken.

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But it will keep them from breaking in the future

radiant stone Oct 21, 2024, 9:43 AM

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hidden geyser also post creation code

but yeah also this

half shard Oct 21, 2024, 9:43 AM

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    _movementComponent = CreateDefaultSubobject<UFloatingPawnMovement>(TEXT("Movement"));

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this is how i construct it

hidden geyser Oct 21, 2024, 9:45 AM

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also, i hope you launch editor from IDE and not try to bruteforce things with live coding

radiant stone Oct 21, 2024, 9:45 AM

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correct, although you don't need the TEXT macro

half shard Oct 21, 2024, 9:45 AM

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hidden geyser also, i hope you launch editor from IDE and not try to bruteforce things with li...

i am launching from my ide

half shard Oct 21, 2024, 9:46 AM

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radiant stone correct, although you don't need the TEXT macro

alright, thanks for the help, i will try the things you suggested

radiant stone Oct 21, 2024, 9:46 AM

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When stuff like this happens I usually cut my losses and rename the component in C++.

hidden geyser Oct 21, 2024, 9:46 AM

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don't see anything wrong. other than that _ ticking me off. usually component name and property name should be same for sanity reasons.

easiest way to debug is set a breakpoint at the CreateDefaultSubobject, when hit set a data breakpoint for a property change at property address, then resume until data breakpoint hits

radiant stone Oct 21, 2024, 9:46 AM

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Renaming both the pointer name and the name given in CreateDefaultSubobject.

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It will be reset to defaults of course, but usually restores the BP functionality.

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Also making sure to have some source control in place!

#Component turns null after construction