get_upgrade_target returns nil althogh to_be_upgraded returns true!?

[ChrislyBear]

Hello fellow Factorioans,

I'm new into Factorio modding, but I have dabbled a bit in Lua. Too little to call myself "experienced", but I have encountered Lua's weirdness ("everything's a table", lol).

I'm the author of a mod called "BotPrioritizer", that I initially thought to be very simple. My mod gives personal robots priority, by cancelling all bot work orders and reissuing them again, so personal robots can take over. Easy, right? Deconstruct everything, Ctrl+Z... nope! But i digress.


So my problem is, that I want to cancel selected upgrades and re-issue them again. I'm checking if an entity is to_be_upgraded(), which returns true. But if I try to get the upgrade target using get_upgrade_target(), I don't get any result back and my variable stays nil.

Here's the code I'm using; it runs at on_player_selected_area and on_player_alt_selected_area and I'm using a selection-tool prototype to make the selection:

Code: Select all

local function handle_selection(event)
    if not event.item == 'bot-prioritizer' then return end

    -- Main logic
    local player = game.get_player(event.player_index)
    local force = player.force

    for _, entity in ipairs(event.entities) do
        if entity.valid then
            if entity.type == "entity-ghost" or entity.type == "tile-ghost" then -- handle ghosts
                if entity.clone({position = entity.position, force = entity.force}) then
                    entity.destroy()
                end
            elseif entity ~= nil and entity.to_be_deconstructed() then -- handle entities to be deconstructed
                entity.cancel_deconstruction(force)
                entity.order_deconstruction(force)
                
-- THIS SECTION DOESN'T WORK
            elseif entity ~= nil and entity.to_be_upgraded() then -- handle upgrades
                local upgrade_proto = entity.get_upgrade_target()
                if upgrade_proto then
                    entity.cancel_upgrade(force, player)
                    entity.order_upgrade({force = entity.force, target = upgrade_proto, player = player})
                else
                    player.print("ERROR: Couldn't find out upgrade target.")
                end
            end
-- SECTION END

        end
    end

    -- Nexela's input for handling tiles
    for _, tile in pairs(event.tiles) do
        if tile.valid then
            local pos = tile.position
            pos.x, pos.y = pos.x + .5, pos.y + .5
            if event.surface.find_entity('deconstructible-tile-proxy', pos) then
                tile.cancel_deconstruction(force, player)
                tile.order_deconstruction(force, player)
            end
        end
    end
    
end

What am I doing wrong? I only ever get the message from the else-branch because upgrade_proto stays nil. Do I have to somehow wait a tick?

Currently I do have a workaround using the events on_marked_for_upgrade and on_cancelled_upgrade to keep track of all the upgrades myself in a global table. Of course there's also a cleanup routine to purge old entities out of this table.

It works, but I'd rather use the built-in API and I find it so weird, that this function doesn't work for me!

What's going on with this function?

Best regards,
Chris

[ChrislyBear]

Nexela, who I also asked about this (since they make the Nanobots mod and also deal with upgrades), filed a bug report: viewtopic.php?f=7&t=90252
Apparently the function upgrade_target() returns nil after a bot has been dispatched, even though the entity hasn't been upgraded yet.

Chris