Is there a onLinkingStart event for linkingtool?

Hi,

I want to have a event listener to capture users linking behavior. To be more specific, when the linking tool starts, I want to set which nodes are toLinkable on the fly. Basically, I want to set all predecessors nodes of the source node is not toLinkable. I did try to use

diagram.toolManager.linkingTool.direction = go.LinkingTool.ForwardsOnly;

But this seems not working.

Could anyone advise me on how to achieve this please?

Regards,
Kakit

You probably want to use a custom link validation predicate.
https://gojs.net/latest/intro/validation.html