Entities tied to the previous UUIDs will not change

[BhasitL]

Entities tied to the previous UUIDs (like dogs, cats, villager trades) will not change. I had to op individual players and use commands to set pets' owner UUIDs for each players:
/execute as @e[type=wolf,distance=..10] run data modify entity @s Owner set from entity @p UUID
/execute as @e[type=cat,distance=..10] run data modify entity @s Owner set from entity @p UUID
/execute as @e[type=parrot,distance=..10] run data modify entity @s Owner set from entity @p UUID

Do you have any idea how to implement it?

Edit: Also thanks a lot for your help concerning the previous issue! I really appreciate your determination to help!! :)

[paul-eff]

Hi @BhasitL ,

I did a little investigation and found out it is actually possible to pull off, but will take a few late nights of coding to implement without bugs.

In short this is what has to be done if you have only a few entities you want to transfer over:

1. Go into your world (in game) and locate an entity you want to change the owner of
2. In the F3 Debug Menu look at the left side (around the middle) where chunk information is displayed. There will be a line that looks something like this:
   ... [0,31 ... r.0.-1.mca] ... (the numbers are just an example!)
3. Locate your world folder, go into the entities folder and then locate the .mca file you saw in the F3 menu (e.g. r.0.-1.mca)
4. Open this file with the NBTExplorer (Windows only, couldn't find anything for Mac/Linux)
5. The top level entries will be chunk coordinates, find the one you saw in the F3 menu (e.g. 0,31)
6. Go through all entities in that chunk until you find your target entity (dog, villager, ...)
7. Convert the real owner's 128-bit UUID to 4 32-bit integers. This afaik can only be done via scripts you can find via Google (nothing tested yet)
8. Find the "owner" entry of this entity and change its 4 32bit integer entry to be the representation of yours
9. Save and reload your world. The e.g. dog should now recognize it's rightful owner again ^^

I will mention this issue in commits that work towards solving this problem to keep you posted.
Cheers

[BhasitL]

Hi @paul-eff ,
Thanks a lot for the detailed instructions! I had actually tried NBTExplorer but I didn't know how to determine the chunk and the Owner field had a weird format not similar to the UUID which I know and it might be the 4 32 bit integer you're talking which I wasn't aware and there was no proper guide online as all were outdated and had a OwnerUUID field that does not exist in newer version. I shall give it a try! Tho, I had over 20 dogs which makes things a bit lengthier compared to the commands. Thanksss a lot!

[EntityinArray]

for loop over all entities in the world and replace the UUIDs i suppose

[paul-eff]

In code this is sadly not as simple @EntityinArray because of the structure of the chunk/entity files.
But you got me thinking and after a little research I found this reddit post .

Via in game commands/command blocks you @BhasitL should be able to query all entities of a specific type and change their owner. I am no expert on in game commands and data manipulation, more research and testing is definitely needed!

IMPORTANT - I did not test this command nor can I say if it even works, I just put together what I think could work:
When you're in game, this or a similar to this command could do the trick:
/execute as @e[type=wolf,nbt={Owner:"<Old_UUID>"}] run data merge entity @s {Owner:"<New_UUID>"}

Feel free to test and give me feedback.
Cheers

[BhasitL]

Hi @paul-eff ,
Thanks a lot for the detailed instructions! I had actually tried NBTExplorer but I didn't know how to determine the chunk and the Owner field had a weird format not similar to the UUID which I know and it might be the 4 32 bit integer you're talking which I wasn't aware and there was no proper guide online as all were outdated and had a OwnerUUID field that does not exist in newer version. I shall give it a try! Tho, I had over 20 dogs which makes things a bit complicated compared to the commands. Thanksss a lot! Concerning the commands, that's what I used and they do work. Thanks a lot tho!

[paul-eff]

Welp, I initially thought this would be a more or less fast and fairly easy implementation: Turns out I first have to write a library that can properly read and write/update the other files. Then I can com back to this issue 😅...