Add Generator Entries

A generator entry (DgEntry) provides template data values through a placeholder resolver (Placeholder), and is selected by the generator script through a generator entry set (DgRegistry).

If you want to add your own entry type, you usually need:

• one custom entry class
• one matching registry
• one placeholder resolver
• and finally a registry registration so the generator system can discover it

If you have not looked at the overall structure yet, start with Runtime Data Generation (Developer). If you prefer to design field access first and wire entries in afterward, you can also begin with Create Placeholder Resolvers.

Create the entry class

public class MyEntry implements DgEntry {
    private final Identifier id;
 
    @Override
    public Identifier getKey() {
        return this.id;
    }
 
    @Override
    public boolean shouldLoad() {
        return true;
    }
    
    // ...
}

Attach a placeholder resolver

The placeholder resolver turns runtime data from the entry into values that can fill a template. See Create Placeholder Resolvers for the full design. Here the goal is only to show how to connect one to an entry.

public class MyEntry implements DgEntry {
    public static final Placeholder<MyEntry> PLACEHOLDER = Placeholder.build(node -> node.then(
        PatternKey.literal("example"), TypeMapper.of(MyEntry::getExample), Placeholder.STRING
    ).concat(DgEntry.PLACEHOLDER, TypeMapper.of(myEntry -> myEntry)));
    
    private final String example;
    
    public String getExample() {
        return this.example;
    }
    
    public Placeholder<? extends MyEntry> placeholder() {
        return PLACEHOLDER;
    }
    
    // ...
}

Note: if your entry class extends another entry type, do not forget to merge in the parent placeholder resolver as well. At minimum, that usually means including DgEntry.PLACEHOLDER.

Create the entry registry

You can either create your own subclass of DgRegistry<MyEntry>, or use helper methods such as DgRegistry.ofEnum(...) and DgRegistry.ofMap(...).

Once created, register it into the API:

static DgRegistry MY_REGISTRY = DgRegistry.ofMap(Map.of(
    Identifier.of("modid:my_entry_1"), new MyEntry(...),
    Identifier.of("modid:my_entry_2"), new MyEntry(...),
    Identifier.of("modid:my_entry_3"), new MyEntry(...)
    // ...
));
static {
    DgRegistry.register(Identifier.of("modid:my_registry"), MY_REGISTRY);
}

After that, the generator script can iterate over the entire entry set just by naming its registry ID:

registry = "modid:my_registry"
# ...

Once the entry and its registry are ready, the next common step is to have a custom data generator actually consume them.