README.md

toml2java

TOML to Java deserializer for Data2Java.

Depends on:

• ../deserializer
• org.tomlj:tomlj

implementation "org.msuo:toml2java:<version>"

Leaf values

class DataModel {
    public String name;
    public Integer port;
}

String toml = """
name = "svc"
port = 8080
""";
DataModel data = new TomlDeserializer().deserialize(toml, DataModel.class);

assertEquals("svc", data.name);
assertEquals(Integer.valueOf(8080), data.port);

Missing keys keep defaults (unknown keys fail)

Missing keys preserve defaults. Unknown keys are reported as UnknownField errors.

class DataModel {
    public String name = "default-name";
    public Integer port;
}

DataModel data = new TomlDeserializer().deserialize("port = 8080", DataModel.class);
assertEquals("default-name", data.name);

Nested objects

class DataModel {
    public Db db;
    static class Db {
        public String host;
        public Integer port;
    }
}

String toml = """
[db]
host = "db"
port = 15432
""";
DataModel data = new TomlDeserializer().deserialize(toml, DataModel.class);

assertEquals("db", data.db.host);
assertEquals(Integer.valueOf(15432), data.db.port);

Optionals

import java.util.Optional;

class DataModel {
    public Optional<String> user = Optional.of("default-user");
}

DataModel present = new TomlDeserializer().deserialize("user = 'alice'", DataModel.class);
DataModel missing = new TomlDeserializer().deserialize("", DataModel.class);

assertEquals(Optional.of("alice"), present.user);
assertEquals(Optional.of("default-user"), missing.user);

Collections and maps

import java.util.List;
import java.util.Map;

class DataModel {
    public List<String> tags;
    public Map<String, Integer> limits;
}

String toml = """
tags = ["a", "b"]

[limits]
api = 10
""";
DataModel data = new TomlDeserializer().deserialize(toml, DataModel.class);

assertEquals(List.of("a", "b"), data.tags);
assertEquals(Integer.valueOf(10), data.limits.get("api"));

Nested generics

import java.util.List;
import java.util.Map;

class GenericBox<T> { public T value; }
class GenericItem<T> { public T payload; }
class StringConstructedGenericKey<T> {
    public final String value;
    public StringConstructedGenericKey(String value) { this.value = value; }
}
class GenericData {
    public GenericBox<List<GenericItem<String>>> foo;
    public Map<StringConstructedGenericKey<Integer>, List<String>> values;
}

String toml = """
[[foo.value]]
payload = "a"

[values]
k1 = ["x", "y"]
""";
GenericData data = new TomlDeserializer().deserialize(toml, GenericData.class);

Class references

interface Service {}
final class ServiceImpl implements Service {}
class DataModel {
    public Class<Service> impl;
}

String toml = "impl = '" + ServiceImpl.class.getName() + "'";
DataModel data = new TomlDeserializer().deserialize(toml, DataModel.class);

assertEquals(ServiceImpl.class, data.impl);

Optional semantics

import java.util.Optional;

class DataModel {
    public Optional<String> user = Optional.of("default-user");
}

// TOML has no explicit null literal. Omitted key behaves as missing.
DataModel data = new TomlDeserializer().deserialize("", DataModel.class);
assertEquals(Optional.of("default-user"), data.user);

See ../../errors.md for error details.