[1.16.5] How to load and hot reload data from JSON

[RisingInIris2017]

To put more specifically, I expect my mod has such a behavior:

1. When Minecraft instance(both client and server) start, load some data from a JSON file.

2. Using these data to do what it should do, until vanilla `/reload` command is executed.

3. Reload new data from that JSON file.

4. Continue to do what it should do.

 

I wrote these codes in my mod's main class:

@Mod("spellbind")
public class Spellbind {

    public static final String MOD_ID = "spellbind";
    public static final String MOD_NAME = "Spellbind";
    private static final Logger LOGGER = LogManager.getLogger();

    public Spellbind() {
        final IEventBus forgeBus = MinecraftForge.EVENT_BUS;

        forgeBus.addListener(this::jsonRulesReader);
    }

    // Read JSON logic
    // Read JSON from datapack, so that modpack makers can set their own "spells".

    private void jsonRulesReader (AddReloadListenerEvent event) {
        event.addListener("something missing");
    }

Then I did find something missing. I had no idea about how to use the `AddReloadListenerEvent`.

I searched the Internet and get this: 

I tried to use the `JsonReloadListener`, but I found I did not understand it, neither.

I do read many Forge forum posts and codes(from other mods and Minecraft vanilla itself), but I still feel difficult.

You are highly appreciated if you could explain what code I should write to achieve my goal.

Thanks in advance!

 

[RisingInIris2017]

I found that if I `new JsonReloadListener`, I should pass two arguments to two parameters of its constructor, the first one is a `Gson`, while second one is a `String`.

I read the code of AdvancementManager, it passes `(new GsonBuilder()).create()` to the first parameter, and passes String `"advancement"` to the second one. So I wrote these codes:

    private void jsonRulesReader (AddReloadListenerEvent event) {
        event.addListener(new JsonReloadListener((new GsonBuilder()).create(), "some String") {
            @Override
            protected void apply(Map<ResourceLocation, JsonElement> objectIn, IResourceManager resourceManagerIn, IProfiler profilerIn) {
                "something need to do"
            }
        });
    }

I wonder what the second parameters mean. What will that string be? Will it become a part of a certain `ResourceLocation`, or a part of file name?

[RisingInIris2017]

Thanks for your kind-hearted explanation! I tried your method and now it can read JSONs from correct ResourceLocation.

private void jsonRulesReader (AddReloadListenerEvent event) {
        event.addListener(new JsonReloadListener((new GsonBuilder()).create(), "rules") {
            @Override
            protected void apply(Map<ResourceLocation, JsonElement> objectIn, IResourceManager resourceManagerIn, IProfiler profilerIn) {
                objectIn.forEach((resourceLocation, ruleJsonElement) -> {
                    try {
                        JsonObject jsonObject = JSONUtils.getJsonObject(ruleJsonElement, "rule");
                        LOGGER.warn(jsonObject);
                    } catch (IllegalArgumentException | JsonParseException e) {
                        LOGGER.error("Parsing error loading custom rules. Message: {}", e.getMessage());
                    }
                });
            }
        });
    }

But I have a new problem: it cannot reload data when I type `/reload` command.

To be more specific, I can reproduce this issue by following steps:

1. Start Minecraft and see it loading my mod's datapack.

2. After it finishes loading, modify a JSON.

3. Execute the `/reload` command.

4. In console log I find that it prints the version of JSON before it was modified.

5. Restart Minecraft, then I can see the modified JSON is loaded.

This is not the behavior I want. I need it to be reloaded everytime the `/reload` command is executed.

So how should I modify my codes to achieve that goal?

[RisingInIris2017]

13 minutes ago, diesieben07 said:

Resources in src/main/resources are copied into the build output folder when running the game, if you modify them while the game is running you have to rebuild.

Oh I got it. I'm using IDEA, so if I want to reload these JSONs, I have to make a datapack and put it into `/run`?

Are there some more easier ways?