Setting a GameState vaule from the GameMode constructor

Development Programming & Scripting C++
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1

I’m trying to create simple multiplayer shooter and have run in to a problem. I’ve a value, CurrentLoadout, that is set on the GameMode, that i want the clients to be able to use. I thought I should set the value to the GameState in the GameMode constructor, but when I’m building the solution, I get an error that the GameState is null. It feels like I’m missing something basic here, but I’ve looked around and can’t find a solution. Any help is appreciated! I cant seem to set the correct tag but the version I’m using is Unreal 5.0.

The error I get when building is:

Exception thrown: write access violation.
GS was nullptr.

ShooterGameMode.h

#pragma once

#include "CoreMinimal.h"
#include "GameFramework/GameModeBase.h"
#include "ShooterGameMode.generated.h"

class ULoadout;
class AShooterGameState;

UCLASS(minimalapi)
class AShooterGameMode : public AGameModeBase
{
	GENERATED_BODY()

public:
	AShooterGameMode();

	UPROPERTY(EditDefaultsOnly)
	ULoadout* CurrentLoadout;
};

ShooterGameMode.cpp

#include "ShooterGameMode.h"
#include "ShooterHUD.h"
#include "ShooterCharacter.h"
#include "UObject/ConstructorHelpers.h"
#include "ShooterGameState.h"

AShooterGameMode::AShooterGameMode()
	: Super()
{
	// set default pawn class to our Blueprinted character
	static ConstructorHelpers::FClassFinder<APawn> PlayerPawnClassFinder(TEXT("/Game/FirstPersonCPP/Blueprints/FirstPersonCharacter"));
	DefaultPawnClass = PlayerPawnClassFinder.Class;

	// use our custom HUD class
	HUDClass = AShooterHUD::StaticClass();

	GameStateClass = AShooterGameState::StaticClass();

	AShooterGameState* GS = GetGameState<AShooterGameState>();
	GS->CurrentLoadout = CurrentLoadout;
}

ShooterGameState.h

#pragma once

#include "CoreMinimal.h"
#include "GameFramework/GameStateBase.h"
#include "ShooterGameState.generated.h"

/**
 * 
 */


class ULoadout;
class AShooterGameMode;

UCLASS()
class SHOOTER_API AShooterGameState : public AGameStateBase
{
	GENERATED_BODY()
public:
	AShooterGameState();

	UFUNCTION(BlueprintCallable, Category = "GameState")
	ULoadout* GetCurrentLoadout();
	
	UPROPERTY(Replicated)
	ULoadout* CurrentLoadout;
};

ShooterGameState.cpp

#include "ShooterGameState.h"
#include "Loadout.h"
#include "Shooter/ShooterGameMode.h" 
#include "Kismet/GameplayStatics.h"
#include "Net/UnrealNetwork.h"

AShooterGameState::AShooterGameState()
{
    bReplicates = true;
};

ULoadout* AShooterGameState::GetCurrentLoadout()
{
    return CurrentLoadout;
};

void AShooterGameState::GetLifetimeReplicatedProps(TArray< FLifetimeProperty >& OutLifetimeProps) const
{
    Super::GetLifetimeReplicatedProps(OutLifetimeProps);
    DOREPLIFETIME(AShooterGameState, CurrentLoadout);
};
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2

Firstly, you should always be checking pointers before you use them. That part is non-negotiable.

Secondly, your issue is occurring because the GameState hasn’t been created yet. The GameMode is responsible for creating the GameState, and its constructor is not responsible for doing that.

Please refer to this function, defined in GameModeBase.h
image

3

Thanks, that seemed to do the trick!

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