Class: UDynamicQuery

class SYSTEMS_API UDynamicQuery
    : public UDynamicIterator;

Reflection-enabled

Specifiers:

• BlueprintType

Dynamic query useful for performing system world queries in blueprints.

One of the goals of Systems Architecture is to provide game designers with means to prototype systems without need for programmers. Dynamic query is a way of performing systems world queries in blueprints. Although blueprint API doesn't have same ergonomics as C++ API because of the lack of lazy iterators on blueprints side, technical game designers still might benefit from quickly testing simple systems without involving programmers into the process and being able to quickly test the idea - it makes failing quicker than it would without technical game designers getting their hands dirty once in a while, which is beneficial to the whole production process in long term.

See USystemsWorld::SpawnQuery.

Example

	UCLASS(BlueprintType)
	class EXAMPLE_API UShiaQueryBundle
	{
		GENERATED_BODY()

	public:
		UPROPERTY(BlueprintReadOnly)
		AActor* Actor = nullptr;

		UPROPERTY(BlueprintReadOnly)
		UShiaComponent* Shia = nullptr;
	};

	auto Query = Systems.DynamicQuery<UShiaQueryBundle>();
	auto* Bundle = NewObject<UShiaQueryBundle>(this, UShiaQueryBundle::StaticClass());
	while (Query->Next(Bundle))
	{
		Bundle->Shia->JustDoIt(Bundle->Actor);
	}

Methods

• EstimateSizeLeft

  public:
  virtual int EstimateSizeLeft() const override;
  

  ---

  Calculates maximum number of items this query can yield.

• Next

  public:
  virtual UObject* Next() override;
  

  ---

  Performs iteration and stores yielded values in returned object.

  Note

  This method uses reflection to figure out properties that gonna store yielded actor and components in returned object.

• Setup

  public:
  void Setup(
      USystemsWorld* Systems,
      const UClass* Type
  );
  

  ---

  Resets internal iterator to state for interating current state of systems world.

  ---

  Arguments

  • Systems

    USystemsWorld* Systems
    

    Pointer to systems world to iterate on.

  • Type

    const UClass* Type
    

    Class of object that contains fields where yielded actor and components are gonna be stored.

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