UE doesn't like my TOptionals...

[Scatter]

The code atm:

    UFUNCTION(BlueprintCallable, Category = "SQLite")
        static void UpdateTileID_Row(
            int32 TileQ,
            int32 TileR,
            int32 TileS,
            TOptional<float> VecX,
            TOptional<float> VecY,
            TOptional<float> VecZ,
            AActor* Store,
            TOptional<int32> Row,
            TOptional<int32> Col
        );

void USQLiteDB::UpdateTileID_Row
    (
        int32 TileQ,
        int32 TileR,
        int32 TileS,
        TOptional<float> VecX,
        TOptional<float> VecY,
        TOptional<float> VecZ,
        AActor* Store,
        TOptional<int32> Row,
        TOptional<int32> Col
    )
{
    // Open the database
    sqlite3* db;
    FString dbPath = FPaths::ProjectContentDir().Append("Database/Current.btf");
    int rc = sqlite3_open(TCHAR_TO_UTF8(*dbPath), &db);
    if (rc != SQLITE_OK)
    {
        // Handle error
        return;
    }

    // Construct the SET clause
    FString setClause;
    if (VecX.IsSet())
        setClause.Append(FString::Printf(TEXT("VecX = %f,"), VecX.GetValue()));
    if (VecY.IsSet())
        setClause.Append(FString::Printf(TEXT("VecY = %f,"), VecY.GetValue()));
    if (VecZ.IsSet())
        setClause.Append(FString::Printf(TEXT("VecZ = %f,"), VecZ.GetValue()));
    if (Store != nullptr)
        setClause.Append(FString::Printf(TEXT("Store = '%s',"), *Store->GetName()));
    if (Row.IsSet())
        setClause.Append(FString::Printf(TEXT("Row = %d,"), Row.GetValue()));
    if (Col.IsSet())
        setClause.Append(FString::Printf(TEXT("Col = %d,"), Col.GetValue()));
    setClause.RemoveFromEnd(",");

    // Prepare the UPDATE statement
    FString sql = FString::Printf(TEXT("UPDATE TileIdentity SET %s WHERE TileQ = %d AND TileR = %d AND TileS = %d"), *setClause, TileQ, TileR, TileS);
    sqlite3_stmt* stmt;
    rc = sqlite3_prepare_v2(db, TCHAR_TO_UTF8(*sql), -1, &stmt, nullptr);
    if (rc != SQLITE_OK)
    {
        // Handle error
        sqlite3_close(db);
        return;
    }

    // Execute the UPDATE statement
    rc = sqlite3_step(stmt);
    if (rc != SQLITE_DONE)
    {
        // Handle error
        sqlite3_finalize(stmt);
        sqlite3_close(db);
        return;
    }

    // Finalize the statement and close the database
    sqlite3_finalize(stmt);
    sqlite3_close(db);
}

Gives the following compile error in the editor: Error: Unable to find ‘class’, ‘delegate’, ‘enum’, or ‘struct’ with name ‘TOptional’ for each line where the TOptional is declared…

I did some searching of the internets and added:

#include "Optional.h"

to my header. File unknown, so even further searches had me adding to my build.cs:

	{
		PCHUsage = PCHUsageMode.UseExplicitOrSharedPCHs; //existing

		PublicIncludePaths.Add("Runtime/Core/Public"); //new-line

		PublicDependencyModuleNames.AddRange(new string[]  //existing
		{  //etc

I’m now at an absolute loss… any ideas?

[Extrone (Arjun Subhash)]

@Scatter

#include "Optional.h"

according to the Documentation it’s

#include "Misc/Optional.h"

[Scatter]

Well that fixed the file unknown error…

However the main error still remains - it doesn’t like the TOptionals (or at least, how I’ve used them).

[Extrone (Arjun Subhash)]

Does the error remain if you remove UFUNCTION()? if it doesn’t, it’s most probably caused by Blueprints not supporting TOptionals.

[EDIT]
Just did some testing, it’s only showing an error if I mark the function as UFUNCTION().
So yeah, Blueprints doesn’t support TOptional.

[Scatter]

Serious? That’s pretty limiting…

Appreciate your effort @Extrone

[Scatter]

So, I’ve done some testing and mucking around and it turns out you can use TOptionals with callable Blueprints, it’s just unecessarily hacky and long winded.

The solution is either a nested private function or sentinel variables. Here’s the blueprint and the returned setclause statement in yellow, bottomleft:

The header code:

	UFUNCTION(BlueprintCallable, Category = "Database")
	static void UpdateReferenceRow
	(
		UPARAM(ref) FIntVector& TileID,
		int32 EmpireID = -1,
		int32 IncidentID = -1,
		int32 NebulaID = -1,
		int32 StellarID = -1
	);

Sauce:

void UQDS_ReferenceTable::UpdateReferenceRow(UPARAM(ref) FIntVector& TileID, int32 EmpireID, int32 IncidentID, int32 NebulaID, int32 StellarID)
{
	// Pass on the IntVec values
	int32 TileQ = TileID.X;
	int32 TileR = TileID.Y;
	int32 TileS = TileID.Z;

	TOptional<int32> E_ID_Value;
	TOptional<int32> I_ID_Value;
	TOptional<int32> N_ID_Value;
	TOptional<int32> S_ID_Value;

	if (EmpireID != -1)
	{
		E_ID_Value = EmpireID;
	}
	
	if (IncidentID != -1)
	{
		I_ID_Value = IncidentID;
	}

	if (NebulaID != -1)
	{
		N_ID_Value = NebulaID;
	}

	if (StellarID != -1)
	{
		S_ID_Value = StellarID;
	}

	// Construct the SET clause
	FString setClause;
	if (E_ID_Value.IsSet())
		setClause.Append(FString::Printf(TEXT("EmpireID = %d,"), E_ID_Value.GetValue()));
	if (I_ID_Value.IsSet())
		setClause.Append(FString::Printf(TEXT("IncidentID = %d,"), I_ID_Value.GetValue()));
	if (N_ID_Value.IsSet())
		setClause.Append(FString::Printf(TEXT("NebulaID = %d,"), N_ID_Value.GetValue()));
	if (S_ID_Value.IsSet())
		setClause.Append(FString::Printf(TEXT("StellarID = %d,"), S_ID_Value.GetValue()));
	setClause.Append(FString::Printf(TEXT("TileQ = %d,"), TileQ));
	setClause.Append(FString::Printf(TEXT("TileR = %d,"), TileR));
	setClause.Append(FString::Printf(TEXT("TileS = %d,"), TileS));
	setClause.RemoveFromEnd(",");

	UE_LOG(LogTemp, Warning, TEXT("Set Clause: %s"), *setClause);
	UE_LOG(LogTemp, Warning, TEXT("Yes, you are here."));
}

It really should be much more straightforward to see if a blueprint node input pin has had a value passed through it, but this definitely works (and has a multitude of uses)…

Oh, and a shoutout to @Hourences for reopening the thread.