Minecraft Inventory Moving Items (1.14)

Question

I was doing some fun things with command blocks, to ensure an item spawned if it doesn't exist in someone's inventory, or already on the pedestal.

(command block 1 repeating, unconditional, always active) --- is it not on the pedestal or in the room (defined by coordinates)?

execute unless entity @e[x=234,y=71,z=-190,dx=9,dy=1,dz=9,tag=Thingie]

(command block 2 chain, conditional, always active) --- is it not in someone's inventory?

execute unless entity @a[nbt={Inventory:[{id:"minecraft:light_gray_stained_glass",tag:{display:{Name:"{\"text\":\"Thingie\",\"color\":\"gold\"}"}}}]}]

(command block 3 chain, conditional, always active) --- then summon one.

summon item 234 70 -186 {Tags:["Thingie"],CustomName:"{\"text\":\"\"}",Item:{id:"minecraft:light_gray_stained_glass",Count:1b,tag:{display:{Name:"{\"text\":\"Thingie\",\"color\":\"gold\"}"}}}}

Everything works... mostly. (sometimes spawns several)

If I open my inventory, click on the item to drag it, or move it around inside my inventory, another gets summoned. Is there another check somewhere to see if it is picked up, but not in my inventory? I've looked all over my player data, and can't find anything... bug?

Anyone have any ideas or suggestions for a better way to do what I want?

Answer 1

You can get the number of matching items someone has, including the items on the cursor, with /clear with a count of 0, like this:

/execute store result score @p scoreboardName run clear @p stone 0

This seems unintuitive, because you're not trying to clear anything and clearing 0 items seems useless, but the return value of /clear with a count of 0, unlike all other counts, is the number of matching items you have, and that's all you're interested in.

One warning: This is currently broken for items that you got from the Creative inventory. A very strange bug: https://bugs.mojang.com/browse/MC-147499
That means when you drop an item in Creative, the count goes to 0 as expected, when you pick it up, it is 1 again, as expected, when you click it, it's still 1, as expected, when you put it down, it's still 1, as expected, but when you then click it again, then it's suddenly 0. Very strange. But if you only use this in Survival/Adventure mode, then it should work fine.