[SPIGOT-6949] Can no longer save lists of config sections to yaml files Created: 28/Feb/22  Updated: 22/Apr/22  Resolved: 22/Apr/22

Status: Resolved
Project: Spigot
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Bug Priority: Minor
Reporter: Nathan Wolf Assignee: Unassigned
Resolution: Fixed Votes: 0
Labels: 1.18.1, 1.18.2
Environment:

Ubuntu, mac OS

Attachments: File UnitTest-1.0-SNAPSHOT.jar    
Version: CraftBukkit version 3445-Spigot-fb0dd5f-05a38da (MC: 1.18.2) (Implementing API version 1.18.2-R0.1-SNAPSHOT)
Guidelines Read: Yes

 Description   

I use lists of config sections to save simple data files.

This would previously serialize as a list of maps. As of 1.18.2 this does not serialize properly:

list:
- !!org.bukkit.configuration.MemoryConfiguration
  defaults: null

Test plugin: https://github.com/NathanWolf/Bukkit-Unit-Tests/releases/tag/config-lists

Code:

YamlConfiguration newConfig = new YamlConfiguration();
List<ConfigurationSection> configList = new ArrayList<>();
MemoryConfiguration newSection = new MemoryConfiguration();
newSection.set("something", "value");
configList.add(newSection);
newConfig.set("list", configList);
try {
    File outputFile = new File(getDataFolder(), "data.yml");
    newConfig.save(outputFile);
    getLogger().info("Wrote to: " + outputFile.getAbsolutePath());
} catch (IOException ex) {
    getLogger().severe("Could not save file: " + ex.getMessage());
}

This is going to cause a lot of data loss for my users with flatfile storage when they update.

I have not narrowed down the specific change, though I see a few suspects. As far as I know things have been working fine since the "save comments" re-work, so I think it's a more recent change.

 Comments   
Comment by blablubbabc [ 18/Apr/22 ]

Can confirm (just encountered this issue myself in one of my plugins): The new serialization no longer accounts for configuration sections that are nested in other types of objects (lists, maps).
I am still not fully sure why we had to switch from YamlRepresenter to the new to/fromNodeTree implementation to convert config sections, but I vaguely remember that Wolf2323 mentioned something about an issue with the order in which objects are serialized or deserialized.

Comment by Nathan Wolf [ 01/Mar/22 ]

Minor update as I try to implement a work-around in my plugin, it seems like serialization just does not descend into lists.

If I convert all the top-level config sections in the list to maps, serialization still fails if there are sections nested in those maps. Example:

list:
- !!org.bukkit.configuration.MemoryConfiguration
  defaults: null
- scalar: 10
  string: something
  section: !!org.bukkit.configuration.MemoryConfiguration
    defaults: null

Code:

YamlConfiguration newConfig = new YamlConfiguration();
List<Object> configList = new ArrayList<>();
MemoryConfiguration newSection = new MemoryConfiguration();
newSection.set("something", "value");
configList.add(newSection);
Map<String, Object> configMap = new HashMap<>();
configMap.put("scalar", 10);
configMap.put("string", "something");
newSection = new MemoryConfiguration();
newSection.set("embedded", "value");
configMap.put("section", newSection);
configList.add(configMap);
newConfig.set("list", configList);
Comment by Nathan Wolf [ 28/Feb/22 ]

Apologies, it does seem like this was caused by SPIGOT-3247 after all. I'm not sure how I haven't noticed until now, or why Paper is unaffected (perhaps their custom Emitter).

I reset back one commit at a time until I found that going back to `ffd8b289` (prior to `3e2dd2bc`, the commit for SPIGOT-3247) restores the previous behavior of saving lists of config sections.

Comment by Nathan Wolf [ 28/Feb/22 ]

I can confirm the issue persists in a fresh 1.18.1 build, but 1.17.1 is ok:

list:
- something: value

That leaves quite a few commits, though I do think this was working for me after updating to the big change to save comments:

SPIGOT-6886: Restore previous behaviour of loading unusual config keys blablubbabc* 1/8/22, 3:04 PM
Fix saving configs which are only a header md_5 1/7/22, 2:39 PM
Add workaround for SnakeYAML 100 comment limit md_5 1/3/22, 2:25 PM
#703: Fix/test yaml anchors and merge Wolf2323* 1/2/22, 12:08 PM
#702: fromNodeTree is now private, this does not belong to the API Wolf2323* 12/28/21, 12:52 PM
#701: Option to configure the max width of a line in the config Wolf2323* 12/26/21, 2:47 PM
SPIGOT-6866: Fixed spaces a between comment indicator and actual comment Wolf2323* 12/23/21, 2:07 PM
Restore protected members to YamlConfiguration md_5 12/22/21, 4:33 PM
SPIGOT-3247: Comment support for YAML files Wolf2323* 12/20/21, 1:35 PM

None of these really seem suspicious though.

Unfortunately I'm not sure how to target a specific commit in BuildTools so it will be difficult for me to narrow this down further.

Comment by Nathan Wolf [ 28/Feb/22 ]

I am sure that it is a problem with the 1.18.2 spigot I just build from BuildTools, but I can not say when it started to be a problem. I don't see this issue on my live servers but I haven't updated them in a while, and they run Paper anyway.

I am trying to narrow it down to the last Spigot version that correctly saved lists of config sections. I don't even see anything in git within the past month that looks config-related, so I am confused too.

Comment by md_5 [ 28/Feb/22 ]

Are you sure? There were no 1.18.2 config changes: https://hub.spigotmc.org/stash/projects/SPIGOT/repos/bukkit/commits/d8a3c3b55674a931391e2905cad4d54acfd15d11

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