How to use ConstructorHelpers::FObjectFinder

Development Programming & Scripting C++
3

Thank you for leading me down the right path! I thought I would share everything else that I came across to solve my problem in case anyone else stumbles here. The end result is at the bottom of the post for others.

How to Use C++ in Unreal Engine 5 - Beginner Tutorial
To start off I was going off this video here to get started but I needed to spawn more than one type of actor blueprint in one spot. So I set out to dynamically change this value during the game.

Load Object vs Static Load Object
The first thing I came across while researching LoadObject is that that it is just a wrapper around calling StaticLoadObject before casting it to type T. It does omit the seventh argument bAllowObjectReconciliation. The LoadObject version saves a few keystrokes, but omits the bAllowObjectReconciliation term. In order to set this value (default: true) you must call StaticLoadObject directly. Changing this to false will cause the inner workings to skip the pre-emptive call to FindObject thereby requiring a LoadPackage call. So I decided to use StaticLoadObject.

StaticLoadObject
Next was learning the spawn parameters, which were quite easy to find

  • The first param will be the class you want with “::StaticClass()” Example: AActor::StaticClass()

  • The articles I was reading said that the InOuter might be who you want to be the parent of the object youre spawning?

  • The next part is a tad confusing… Name is where you put the file path/ the reference from the content browser and FilePath you cna just set to NULL

  • You can find the LoadFlags online and what they do here: ELoadFlags

  • I am not sure what Sandbox does… but you can just set that to null too if you just need the object.

I had trouble getting the blueprint to spawn because the class that came out of the StaticLoadObject. I was using AActor at this time. SO after more research I learned the proper way spawn the blueprint as an actor which I came to this forum post:
How to spawn a blueprint actor via C++

Here is the final solution and it works! Thanks for reading.
Here is the header file:

// Fill out your copyright notice in the Description page of Project Settings.

#pragma once

#include "CoreMinimal.h"
#include "GameFramework/Actor.h"
#include "ActorSpawnerCPP.generated.h"

UCLASS()
class SPACEFORCEUNREAL_API AActorSpawnerCPP : public AActor
{
	GENERATED_BODY()
	
public:	
	// Sets default values for this actor's properties
	AActorSpawnerCPP();


	UFUNCTION(BlueprintCallable, Category = "Abilities")
		void SpawnNewActor();

	UFUNCTION(BlueprintCallable, Category = "Abilities")
		bool GetNewActorByName(FString newActorName);


	UPROPERTY(EditAnywhere)
		TSubclassOf<AActor> actorBPToSpawn;

	UFUNCTION(BlueprintCallable)
		void SetFileLocation(FString newLoc);

	UPROPERTY(EditAnywhere)
		FString fileLocation;


protected:
	// Called when the game starts or when spawned
	virtual void BeginPlay() override;

public:	
	// Called every frame
	virtual void Tick(float DeltaTime) override;

};

Here is the Finished Code:

bool AActorSpawnerCPP::GetNewActorByName(FString newActorName) 
{
	bool foundActor = false;
	// file location should be:
	// Blueprint'/Game/ObjectsToBeAdded/Blueprints/
	// specifically Blueprint'/Game/ObjectsToBeAdded/Blueprints/BP.BP'
	//  or it could be Blueprint'/Game/ObjectsToBeAdded/Blueprints/PleaseWork.PleaseWork'
	FString tempFileLoc = fileLocation + newActorName + "."+newActorName;

	// this is the hard coded way for the object but it still does not find it
	tempFileLoc = "Blueprint'/Game/ObjectsToBeAdded/Blueprints/PleaseWork.PleaseWork'";

	UObject* newActor = Cast<UObject>(StaticLoadObject(UBlueprint::StaticClass(), NULL, *tempFileLoc, NULL, LOAD_None, NULL));
	UBlueprint* GeneratedBP = Cast<UBlueprint>(newActor);

	if (newActor != nullptr) {

		actorBPToSpawn = GeneratedBP->GeneratedClass;

		foundActor = true;
	}
	else {
		UE_LOG(LogTemp, Error, TEXT("Could not find %s in the location: %s"), *newActorName, *tempFileLoc);
	}
	return foundActor;
}

This is called later down the Line:


// a simple 
void AActorSpawnerCPP::SpawnNewActor()
{

	if (actorBPToSpawn != NULL)
	{
		FActorSpawnParameters spawnParams;
		spawnParams.SpawnCollisionHandlingOverride = ESpawnActorCollisionHandlingMethod::AdjustIfPossibleButAlwaysSpawn;

		GetWorld()->SpawnActor<AActor>(actorBPToSpawn, GetActorTransform(), spawnParams);
	}
	else {
		UE_LOG(LogTemp, Error, TEXT("actorBPToSpawn is null"));
	}
	
}
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