NeoForge Update Checker

NeoForge provides a very lightweight, opt-in, update-checking framework. If any mods have an available update, it will show a flashing icon on the 'Mods' button of the main menu and mod list along with the respective changelogs. It does not download updates automatically.

Getting Started

The first thing you want to do is specify the updateJSONURL parameter in your mods.toml file. The value of this parameter should be a valid URL pointing to an update JSON file. This file can be hosted on your own web server, GitHub, or wherever you want as long as it can be reliably reached by all users of your mod.

Update JSON format

The JSON itself has a relatively simple format as follows:

{
  "homepage": "<homepage/download page for your mod>",
  "<mcversion>": {
    "<modversion>": "<changelog for this version>", 
    // List all versions of your mod for the given Minecraft version, along with their changelogs
    // ...
  },
  "promos": {
    "<mcversion>-latest": "<modversion>",
    // Declare the latest "bleeding-edge" version of your mod for the given Minecraft version
    "<mcversion>-recommended": "<modversion>",
    // Declare the latest "stable" version of your mod for the given Minecraft version
    // ...
  }
}

This is fairly self-explanatory, but some notes:

• The link under homepage is the link the user will be shown when the mod is outdated.

• NeoForge uses an internal algorithm to determine whether one version string of your mod is "newer" than another. Most versioning schemes should be compatible, but see the ComparableVersion class if you are concerned about whether your scheme is supported. Adherence to Maven versioning is highly recommended.

• The changelog string can be separated into lines using \n. Some prefer to include a abbreviated changelog, then link to an external site that provides a full listing of changes.

• Manually inputting data can be chore. You can configure your build.gradle to automatically update this file when building a release as Groovy has native JSON parsing support. Doing this is left as an exercise to the reader.

• Some examples can be found here for nocubes, Corail Tombstone and Chisels & Bits 2.

Retrieving Update Check Results

You can retrieve the results of the NeoForge Update Checker using VersionChecker#getResult(IModInfo). You can obtain your IModInfo via ModContainer#getModInfo. You can get your ModContainer using ModLoadingContext.get().getActiveContainer() inside your constructor, ModList.get().getModContainerById(<your modId>), or ModList.get().getModContainerByObject(<your mod instance>). You can obtain any other mod's ModContainer using ModList.get().getModContainerById(<modId>). The returned object has a method #status which indicates the status of the version check.

Status	Description
FAILED	The version checker could not connect to the URL provided.
UP_TO_DATE	The current version is equal to the recommended version.
AHEAD	The current version is newer than the recommended version if there is not latest version.
OUTDATED	There is a new recommended or latest version.
BETA_OUTDATED	There is a new latest version.
BETA	The current version is equal to or newer than the latest version.
PENDING	The result requested has not finished yet, so you should try again in a little bit.

The returned object will also have the target version and any changelog lines as specified in update.json.