What is the direction of data flow in On Parameters Changed compared to Event Handler?

The correct understanding of the data flow in the context of "On Parameters Changed" compared to "Event Handler" is that data flows from the parent to the Block and then from the Block back to the parent. This two-way communication is essential for ensuring that changes in the parameters that are passed from the parent to the Block can be processed and, if necessary, returned to the parent for further action.

When a parameter changes in the parent, the "On Parameters Changed" event allows the Block to react to those changes. This mechanism ensures that the Block can adapt its behavior based on the new values it receives, thereby enabling responsive and dynamic UI behavior. After the Block processes the new parameters, it can also alert the parent of updates or changes that may have occurred internally, reflecting the changes made during the Block's operation.

This flow contrasts with other options by emphasizing that data can move in both directions, enhancing the interaction between the parent component and the Block. This enables a more cohesive and maintainable component structure within the OutSystems framework, facilitating better modular programming practices.