---

title: Overview sidebar_position: 1 id: index license: | Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

This document explains generated code for each target language.

Fory IDL generated types are idiomatic in host languages and can be used directly as domain objects. Generated types also include to/from bytes helpers and schema modules or registration helpers, depending on the target language.

Generated schema modules are named from the schema source file, not from the package or namespace. In targets that expose the module directly in a language package or namespace, names such as AddressbookForyModule or ComplexPbForyModule let multiple IDL files target the same package or namespace without producing colliding ForyModule types.

Reference Schemas

The examples below use two real schemas:

1. addressbook.fdl (explicit type IDs)
2. auto_id.fdl (no explicit type IDs)

addressbook.fdl Excerpt

package addressbook;

option go_package = "github.com/myorg/myrepo/gen/addressbook;addressbook";

message Person [id=100] {
    string name = 1;
    int32 id = 2;

    enum PhoneType [id=101] {
        PHONE_TYPE_MOBILE = 0;
        PHONE_TYPE_HOME = 1;
        PHONE_TYPE_WORK = 2;
    }

    message PhoneNumber [id=102] {
        string number = 1;
        PhoneType phone_type = 2;
    }

    list<PhoneNumber> phones = 7;
    Animal pet = 8;
}

message Dog [id=104] {
    string name = 1;
    int32 bark_volume = 2;
}

message Cat [id=105] {
    string name = 1;
    int32 lives = 2;
}

union Animal [id=106] {
    Dog dog = 1;
    Cat cat = 2;
}

message AddressBook [id=103] {
    list<Person> people = 1;
    map<string, Person> people_by_name = 2;
}

auto_id.fdl Excerpt

package auto_id;

enum Status {
    UNKNOWN = 0;
    OK = 1;
}

message Envelope {
    string id = 1;

    message Payload {
        int32 value = 1;
    }

    union Detail {
        Payload payload = 1;
        string note = 2;
    }

    Payload payload = 2;
    Detail detail = 3;
    Status status = 4;
}

union Wrapper {
    Envelope envelope = 1;
    string raw = 2;
}

Cross-Language Notes

Type ID Behavior

• Explicit [id=...] values are used directly by generated module installation or registration helpers.
• When type IDs are omitted, generated code uses computed numeric IDs (see auto_id.* outputs).
• If option enable_auto_type_id = false; is set, generated module installation or registration helpers use name-based APIs instead of numeric IDs.

Nested Type Shape

Language	Nested type form
Java	Person.PhoneNumber
Python	Person.PhoneNumber
Rust	person::PhoneNumber
C++	Person::PhoneNumber
Go	Person_PhoneNumber (default)
C#	Person.PhoneNumber
JavaScript/TypeScript	Person.PhoneNumber
Swift	Person.PhoneNumber
Dart	Person_PhoneNumber
Kotlin	PersonPhoneNumber
Scala	Person.PhoneNumber

Byte Helper Naming

Language	Helpers
Java	toBytes / fromBytes
Kotlin	toBytes / fromBytes
Scala	toBytes / fromBytes
Python	to_bytes / from_bytes
Rust	to_bytes / from_bytes
C++	to_bytes / from_bytes
Go	ToBytes / FromBytes
C#	ToBytes / FromBytes
JavaScript/TypeScript	(via fory.serialize())
Swift	toBytes / fromBytes
Dart	(via fory.serialize())

Language References

Choose the generated-code reference for the target language. Generated models remain ordinary language-native types and use the supported Fory serialization APIs for that language.

Language	Generated-code reference
Java	Java
Python	Python
C++	C++
Go	Go
Rust	Rust
JavaScript/TypeScript	JavaScript/TypeScript
C#	C#
Swift	Swift
Dart	Dart
Scala	Scala
Kotlin	Kotlin