TryLoad failed since version 4.15

Development Programming & Scripting Blueprint
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1

In version 4.14 the TryLoad function worked without any problem for blueprint objects.
Since version 4.15, the object isn’t loaded.

AKPickupObject* UKObjectManagerDefinition::GetPickupObject(FString UID)
{
	if (ObjectLookupTable)
	{
		const FKBasicObjectDefinitionStruct* Data = ObjectLookupTable->FindRow<FKBasicObjectDefinitionStruct>(*UID, TEXT(""));
		if (Data)
		{
			if (Data->Object.IsPending())
			{
				UObject* Asset = Data->Object.ToStringReference().TryLoad();
				if (Asset == nullptr)
				{
					UE_LOG(LogKSGM, Log, TEXT("UKObjectManagerDefinition::GetPickupObject: Still couldn't load Data->Object"));
				}
			}
			UBlueprint* Blueprint = Data->Object.Get();
			if (Blueprint)
			{
				check(Blueprint->GeneratedClass->IsChildOf(AKPickupObject::StaticClass()));
				UClass* Class = Blueprint->GeneratedClass;
				AKPickupObject *PickupObject = CastChecked<AKPickupObject>(Class->GetDefaultObject());
				return PickupObject;
			}
		}
	}
	return NULL;
}

UTexture2D* UKObjectManagerDefinition::GetPickupObjectTexture(FString UID)
{
	if (ObjectLookupTable)
	{
		const FKBasicObjectDefinitionStruct* Data = ObjectLookupTable->FindRow<FKBasicObjectDefinitionStruct>(*UID, TEXT(""));
		if (Data)
		{
			if (Data->Icon.IsPending())
			{
				UObject* Asset = Data->Icon.ToStringReference().TryLoad();
				if (Asset == nullptr)
				{
					UE_LOG(LogKSGM, Log, TEXT("UKObjectManagerDefinition::GetPickupObjectTexture: Still couldn't load Data->Icon"));
				}
			}
			// Add the icon to root to avoid the element from being destroyed by the GC
			if (Data->Icon.IsValid() && !Data->Icon->IsRooted())
				Data->Icon->AddToRoot();
			return Data->Icon.Get();
		}
	}
	// Not found, return the unknown object texture
	return UKObjectManagerDefinition::GetPickupObjectUnknownTexture();
}

The objects are stored in a data table.

134073-datatable.png
134073-datatable.png1206×792 83.7 KB

For loading the icon with GetPickupObjectTexture(FString UID), no problem.
But loading the blueprint object with GetPickupObject(FString UID), always return NULL.

I don’t think if it is linked with the new option for Nativization.

Thanks for your help.

2

It looks like you’re referencing the Blueprint asset directly, rather than reference its generated class. That won’t work in a cooked build.

3

Ok.
It was working in version 4.14. I changed nothing.
What do I need to change in order to take the reference from the DataTable object ?

4

I’ve found a way to load the objects using FindObject function.

AKPickupObject* UKObjectManagerDefinition::GetPickupObject(FString UID)
{
	if (ObjectLookupTable)
	{
		const FKBasicObjectDefinitionStruct* Data = ObjectLookupTable->FindRow<FKBasicObjectDefinitionStruct>(*UID, TEXT(""));
		if (Data)
		{
			/* @todo Check with epic why we do need to call the 
			 *       TryLoad function before using FindObject
			 *       If not, the FindObject always return NULL.
			 */
			if (Data->Object.IsPending())
			{
				UObject* Asset = Data->Object.ToStringReference().TryLoad();
			}
			FString objectName = Data->Object.ToStringReference().ToString() + FString("_C");
			UClass* blueprintClass = FindObject<UClass>(ANY_PACKAGE, *objectName);
			if (blueprintClass->IsChildOf(AKPickupObject::StaticClass()))
			{
				AKPickupObject *PickupObject = CastChecked<AKPickupObject>(blueprintClass->GetDefaultObject());
				return PickupObject;
			}
			UE_LOG(LogKSGM, Log, TEXT("UKObjectManagerDefinition::GetPickupObject: Couldn't load Data->Object  <%s>"), *objectName);

		}
	}
	UE_LOG(LogKSGM, Log, TEXT("UKObjectManagerDefinition::GetPickupObject: Invalid data table. Check the BasicObjectData."));
	return NULL;
}

But there is a strange behaviour.
If I don’t call

if (Data->Object.IsPending())
{
	UObject* Asset = Data->Object.ToStringReference().TryLoad();
}

before the call

UClass* blueprintClass = FindObject<UClass>(ANY_PACKAGE, *objectName);

it always returns NULL.

What is doing TryLoad(), even if the function call always return NULL, to make FindObject() returning the right object instead of NULL ?

5

You probably want to use FStringClassReference instead for your class reference, then you can just call TryLoadClass on it to get your class reference. The type given to the template parameter would be the instance type of the class, AKPickupObject in your case.

I’m pretty sure that an FStringAssetReference property can’t auto-convert to a FStringClassReference, so you may have to export your Data Table, make the property change, convert the class references to use the _C BP reference (so they reference the class rather than the BP), and then re-import your Data Table.

6

Ok I’ll try.
Thank you for your answer.