Skip to main content

Blueprint API Reference

This page provides a detailed reference for all the custom Blueprint nodes provided by the FactsDB plugin.

Main K2Nodes​

These are the primary nodes you will use to interact with the FactsDB system.

Get Fact by Tag​

Get Fact by Tag node A pure node that retrieves the value of a single fact from a specified context.

  • Context ID (In): The unique runtime ID of the context to read from.
  • Value (Out): The current value of the fact. The pin's data type is dynamically determined by the Fact To Access selected in the node's Details panel.
  • Operation Result (Out): An FFactOperationResult struct. Break this to check bSuccess to see if the fact was found.

Update Fact by Tag​

Update Fact by Tag node

An execution node that sets the value of a single fact in a specified context.

  • Exec (In/Out): Standard execution pins.
  • Context ID (In): The unique runtime ID of the context to write to.
  • Value (In): The new value to assign to the fact. The pin's data type is dynamically determined.
  • Operation Result (Out): An FFactOperationResult struct. bSuccess will be false if the update failed (e.g., no network authority, or the fact is read-only).

Get Multiple Facts​

Get Multiple Facts node A pure node that retrieves the values of several facts from a single context in one efficient operation.

  • Context ID (In): The context to read from.
  • Fact Output Pins (Out): The node dynamically generates one output value pin for each fact listed in its Details panel configuration.
  • Operation Result (Out): An FFactBatchQueryResult struct. Break this to see if the overall operation was successful and which, if any, facts were not found.

Evaluate Query​

Evaluate Query node

A pure node that evaluates a data-driven query and returns a boolean result.

  • Target Context (In): The primary context the query will be evaluated against.
  • Instigator Context (In): A secondary context, often representing the actor initiating the query (e.g., the player).
  • Return Value (Out): A boolean that is true if the query's conditions are met, and false otherwise.

Asynchronous Nodes​

These latent nodes handle operations that occur over time.

Listen For Fact Changes​

Listen For Fact Changes node Listen For Fact Changes node

An asynchronous node that fires an event every time a specific fact (or any fact) changes.

  • Node Configuration: The node's behavior is configured in the Details panel via the Listen Level property, which changes the available input pins.
  • On Fact Changed (Out Exec): The execution pin that fires when a matching fact is updated.
  • Data Pins (Out): Provides the SourceComponent of the change, the FactDefinitionTag that changed, and the OldValue and NewValue.
  • Then (Out Exec): Fires once immediately after the listener has been successfully activated.
  • Async Action (Out): Outputs the listener object itself, which can be stored and used to Cancel the listener later.

Wait For Fact Value​

Wait For Fact Value node

An asynchronous node that waits until a specific fact meets a certain value condition.

  • Expected Value (In): The value to compare against. The pin type is resolved dynamically.
  • Comparison Type (In): The type of comparison to perform (Equal, NotEqual, Greater, etc.).
  • Timeout (In): How long to wait in seconds before giving up. A value of 0 or less means wait forever.
  • On Condition Met (Out Exec): Fires once when the fact's value satisfies the condition.
  • On Timeout (Out Exec): Fires if the timeout duration is reached before the condition is met.
  • Current Fact Value (Out): Provides the fact's value at the moment the condition was met or the timeout occurred.

Utility Nodes​

Make Fact Update Payload​

Make Fact Update Payload node A pure node used to construct a single entry for a batch update operation.

  • Inputs: Takes a Context ID and a Value for a specific fact (resolved via the Details panel).
  • Payload (Out): Outputs a single FFactBatchUpdatePayload struct.
  • Usage: Use this node with a Make Array node to build a list of payloads to pass into the Update Facts in Batch function.

Update Facts in Batch (Function)​

Update Facts in Batch function

A standard library function that takes an array of payloads and applies all the changes in one efficient, atomic operation. This is the most performant way to update many facts at once as it only triggers a single batch of change events.

Fact Action: [Action Name] (Dynamic)​

Fact Action node

These nodes are generated dynamically for every Blueprint class that inherits from UFactAction_Async. They provide a powerful way to create complex, reusable, and stateful asynchronous gameplay logic.

  • Inputs: Activate and Cancel execution pins. Data inputs depend on the properties exposed in the specific action's Blueprint class.
  • Outputs: OnSuccess and OnFailure execution pins, which are triggered from within the action's own graph logic. Also outputs the ActionObject instance.