A blueprint library for unreal engine with functions available in blueprints to start a customized play session in the editor. It can be for instance used in editor widget utilities for quick actions... like starting a standalone session (with client and server) with a different map used for the client but the current map opened in the editor le…

PlayFromBlueprintLibrary.cpp

#include "PlayFromBlueprintLibrary.h"

#if WITH_EDITOR

#include "LevelEditor.h"

void UPlayFromBlueprintLibrary::PlayFrom(
	FString LevelName,
	const EPlayNetMode PlayNetMode,
	const int32 NumberOfClients,
	const bool bLaunchServer)
{
	ULevelEditorPlaySettings* LevelEditorPlaySettings = GetMutableDefault<ULevelEditorPlaySettings>();
	LevelEditorPlaySettings->bLaunchSeparateServer = bLaunchServer;
	LevelEditorPlaySettings->SetPlayNetMode(PlayNetMode);
	LevelEditorPlaySettings->SetPlayNumberOfClients(NumberOfClients);
	LevelEditorPlaySettings->SetRunUnderOneProcess(true);

	FLevelEditorModule& LevelEditorModule = FModuleManager::Get().GetModuleChecked<FLevelEditorModule>(TEXT("LevelEditor"));
	FRequestPlaySessionParams RequestPlaySessionParams;
	RequestPlaySessionParams.EditorPlaySettings = LevelEditorPlaySettings;
	RequestPlaySessionParams.GlobalMapOverride = LevelName;
	// If only one client is expected then use the editor level viewport as game viewport.
	if (NumberOfClients == 1)
	{
		RequestPlaySessionParams.DestinationSlateViewport = LevelEditorModule.GetFirstActiveViewport();
	}
	GEditor->RequestPlaySession(RequestPlaySessionParams);
}

#endif

PlayFromBlueprintLibrary.h

#pragma once

#if WITH_EDITOR

#include "CoreMinimal.h"
#include "Settings/LevelEditorPlaySettings.h"
#include "PlayFromBlueprintLibrary.generated.h"

UCLASS()
class UPlayFromBlueprintLibrary : public UBlueprintFunctionLibrary
{
	GENERATED_BODY()

public:
	// Starts a play session with a specified level name.
	// Optionally the PlayNetMode and the number of client windows can be specified.
	// If the number of clients is just one then the editor level viewport is the play window for the first client.
	// If a server is required it can be optionally specified, then a separate server will be started.
	UFUNCTION(BlueprintCallable)
	static void PlayFrom(
		FString LevelName,
		const EPlayNetMode PlayNetMode = PIE_Client,
		const int32 NumberOfClients = 1,
		const bool bLaunchServer = true);
};

#endif