Detect a cycle in a GraphEdit in Godot.

creates_cycles.gd

#Attach to GraphEdit
func creates_cycle(from_node: StringName,  to_node: StringName):
	var from:GraphNode=get_node(NodePath(from_node))
	var to:GraphNode=get_node(NodePath(to_node))
	var links:={from_node:{to_node:true}}
	for con in get_connection_list():
		var list:Dictionary=links.get_or_add(con.from_node,{})
		list[con.to_node]=true
	var stack=[]
	var visited={}
	stack.push_back(from_node)
	while not stack.is_empty():
		var current=stack.pop_back()
		visited[current]=true
		var linked:Dictionary=links.get(current,{})
		for child in linked.keys():
			if visited.get(child,false):
				return true
			stack.push_back(child)
	return false