I will provide a screenshot and a relatively small repro project.
Every time I start my project I get placeholder errors. They are fixed by compiling so while it may not be a big issue by itself, I have a project that is very unstable and I am suspecting this issue to be part of the problem.
In all seriousness, this is so complicated to explain… I think the screenshot explains it the best.
My class “FSM” has a Tmap (State class - State reference kvp).
The FSM class creates a state class. If the State class attempts to Find something in the Tmap, there is no error. The State class then creates a Transition class. If the Transition class attempts to Find something in the Tmap, after a project restart, it is dirty with a placeholder error on the Find node.
The way the FSM class creates the State class is by using a class variable from a Data table. While one data table works fine, using two (see screenshot) will cause the place holder error.
Open the following classes: FSM, State and Transition.
The transition class will have the placeholder error on the Find node inside the function Initialize. The state class also have this setup inside its Initialize function, but that gives no error.
Go to the FSM class, Initialize function. If the red marked Data table is skipped, then there is no error.
Update: The following is a screenshot from my bigger project, not the repro. they do share much of the setup. So the actor that creates the fsm Uobject after its creation then calls the initialize function, but on every restart that node gives an error (1).
Additionally, after implementing a Patrol state, child of State class, which calls the FSM class to add a MoveTo State to a stack, gives a placeholder error (2).
Going back to the FSM initialize function, where the data table setup is (3). While it looks a bit different from the repro project, it is practically the same and if it is connected, the errors appears and if tables are disconnected, compiled and project restarted the errors does not appear.
So I no longer think that Tmaps is part of the issue, rather that having classes inside Data Tables. But not just having classes inside Data tables, but having in the particular way the repro is set up for some reason. In the repro, the “Unitbehaviour” DT simply points at another data table and a row, and only the row is used to get the row of the state in order to get the correct class. Somehow the engine does not like that.
Update 2: In an attempt to be able to pull data from data tables as I do here, I moved the Data table logic to the actor that creates the FSM and passing in an array of the data into the Initialize function of the FSM class, and this does not result in any error. So I guess it’s somehow because the way the data tables are setup inside specifically an UObject?
