FTB Essentials Kits Drop Contents

[RoyalT20]

Hello friends! I've been trying to use the somewhat new FTB Essentials kit commands for several functions, including to provide playtime based rewards through integration with FTB Ranks. The FTB ranks portion took a huge step forward this week thanks to the work of desht in issue 1274. With that new feature on its way solving half of what I was looking for, which I'll be real with you I wasn't sure was ever going to get development priority as a feature, we need to address kits themselves and their current state.

I have never had kits work properly and crawling the web and support forums I can't find anyone else who has either. Which is way too bad since I love the potential here! The problem is that kits in every pack I've made or tested drop their contents constantly. Wait an hour or three and check the kit contents? You'll get back an array of blank elements, which interestingly enough at least keeps the same number of elements as the kit had when created. Restart the server? Same issue. It won't matter if you create the kits from the hot bar, inventory, or container, even if you leave the container in the world with the kit contents. So, two questions that I think will be helpful to kick us off:

1- To even start tracking down the problem and if the issue is with the kits feature itself we need more info on where kit data is supposed to be stored. Ideally a file with this data would be created somewhere, likely in the world folder if it were to match the rest of the FTB mods. If this data were stored as its own file it would also be easy to export/import to other worlds and packs, and to bulk modify, both of which would be so nice. So yeah, do any contributors or forum goers here know where kit data is stored, or even if it is written somewhere at/after creation?

2- If the kit data is in fact saved somewhere that should be persistent, the next question would be why isn't it acting like it? I have no insight on this since I can't find where the data is written yet.

Very best-case scenario for this discussion is that someone provides a link to a closed Issue here that I missed which addresses both of these questions, but at just this moment I'm not aware that FTB developers even know this is an issue. Personally, I think kits would get a lot more love from the community if they actually worked, as I imagine packs designers would simply adore showing off what they could do with it once it is working as intended.

[RoyalT20]

Answering some of my own questions here, I must not have been very committed to digging last time or I forgot what I found, lol! Okay so the answer to question 1 is that kits are written into the data.snbt file in the world/ftbessentials directory. Its not it's own file like my best-case scenario above, but we'll work with it! The kit JSON data is a blank set of the number of items in the initial kit, so like I described in the initial post it reads in game like an array of blank values. Here's a test world's data.snbt file contents after creating two kits:

{
warps: { }
mute_timeouts: { }
kits: {
MA_starter: {
cooldown: 0L
items: [
{ }
{ }
{ }
{ }
{ }
]
}
Artisan: {
cooldown: 0L
items: [ ]
}
}
}

With question 1 answered I'm digging into the kit code to find why that data isn't writing anything at all in the items tags. If I can find that and any follow-up needs, I think I will close this discussion in favor of an issue with a proposed solution.

[RoyalT20]

Disclaimer up front, I have never developed a Minecraft mod and my Java is rusty, please be kind if I use a wrong term somewhere or misunderstand some seemingly obvious logic since I am just doing as much as I can to help the devs here.

First some logic to save us time. From the initial discussion post, if the data.snbt file does get reloaded for whatever reason while the world is active and there legitimately is a problem either saving or loading kit contents, that would explain why the kit contents disappear after some time or trigger I am not aware of even if the server does not restart. This would explain why the data doesn't seem persistent even when the server isn't restarted, so question 2 can be put to bed. We answered question 1 in the last post, so the new question, which we'll call question 3 for easy reference, is to track down is why there is no item data in the kits JSON.

A very quick look at the load process and sub processes looks fine honestly, but I don't even need to worry about that yet since I have never observed the JSON/NBT data in data.snbt to have item values in the first place. We can come back to load issues if those fail after we fix the kits saving in the first place if that even becomes necessary. I'm also quite sure the SNBTCompundTag object and processes are fine since other things here work without issue, but since I am new to Minecraft mod development I'm going to go learn about those before continuing. Okay, key-value pairs, technically not JSON, compound tags we can see already, not bad so far, brb.

Resurfacing for a moment from Minecraft code, we're just building compounding tags here so we need to trace from the toNBT method in FTBEWorldData.java down to where the items themselves are added to the compound tag, which appears to be in the saveStack method of Kit.java. Most of that is straightforward, it looks like I need to dig into the ItemStack class next which means more Minecraft code, brb again.

Okay here's where I'm at right now. The offending line of the saveStack method currently reads as "stack.save(provider, tag);" which I'm assuming is supposed to save the referenced ItemStack object to the provided tag. Past this I am speculating until I can get better decompiled code for the ItemStack class and/or understand the Kit.java methods better.

[RoyalT20]

At this point I've examined everything I have access to in the code right now. My best guess for a solution is that there is likely a missing tag.put call that takes the return of the current "stack.save(provider, tag)" line as an argument. For anyone who hasn't looked through all the comments up to this point, this call is currently on line 68 of the Kit.java class. This solution assumes that the ItemStack class has a valid save(HolderLookup.Provider provider, CompoundTag tag) method, that it operates similar to the other calls for ItemStack objects I've looked at in the related classes, and that it returns a CompoundTag object. The rest of the code looks great so I can't imagine why the stack.save call wouldn't return something valid within these conditions.

My second best guess is that the stack.save call may already be trying to write to the provided tag, and if so that the call is providing a return than cannot be parsed into the data.snbt file when all the tags roll up to that point.

[desht]

See #1496