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typeid-kotlin

A Kotlin implementation of TypeID.

TypeIDs are a modern, type-safe, globally unique identifier based on the upcoming UUIDv7 standard. They provide a ton of nice properties that make them a great choice as the primary identifiers for your data in a database, APIs, and distributed systems. Read more about TypeIDs in their spec.

Based on the Java implementation from fxlae/typeid-java.

This implementation adds a more complete type safety including id and their prefixes and uses an idiomatic Kotlin API.

API Documentation

Dependency

To use with Maven:

<dependency>
    <groupId>earth.adi</groupId>
    <artifactId>typeid-kotlin</artifactId>
    <version>1.0.0</version>
</dependency>

To use via Gradle:

implementation("earth.adi:typeid-kotlin:1.0.0")

Usage

The TypeId class is the main entry point for working with TypeIDs. The class can be used to generate Id instances or parse them from strings. They are typesafe, immutable and thread-safe.

Generating ids

To use the typed features of the library, you need to define your typed id associated with an entity.

// Define your identifiable entity type:
data class User(val id: UserId) // can contain other fields

// Define a typealias for the user id.
typealias UserId = Id<out User>

generate

To generate a new Id, based on UUIDv7 as per specification:

// create a reusable TypeId instance, can be stored in a DI container
val typeId = typeId()

val userId: UserId = typeId.generate()
println(userId) // prints something like user_01h455vb4pex5vsknk084sn02q
println(typeId.typedPrefix.prefix) // "user"
println(typeId.uuid) // java.util.UUID(01890a5d-ac96-774b-bcce-b302099a8057)

This is inferring the Java type of the typeid to UserId.

Alternatively, specifying the entity type, for example for User, will also generate the associated id UserId:

val userId = typeId.generate<User>()

Or specify the type explicitly, which can also be used from Java code as it does not rely on Kotlin type inference:

val userId = typeId.generate(User::class.java)

If the type of the id can be inferred, it will also work seamlessly:

data class User(val id: UserId)
val user = User(typeId.generate()) // infers UserId

Alternatively, directly use the static methods in TypeId:

val userId: UserId = TypeId.generate()

Using an explicit string prefix will instead generate a RawId:

val rawId: RawId = typeId.generate("custom")
println(rawId) // prints something like custom_01h455vb4pex5vsknk084sn02q

Raw ids are just a string with a prefix and a UUID, without any Java/Kotlin type information, so it is better to use typed ids whenever possible (see Type safety below).

All methods described below also have raw variants.

of

To construct (or reconstruct) an Id from an UUID:

val userId: UserId = typeId.of(someUUID)

or for a RawId:

val userId: RawId = TypeId.of("user", someUUID)

Parsing from strings

For parsing, the library supports both an imperative programming model and a more functional style.

parse

The most straightforward way to parse the textual representation of an id:

val userId: UserId = typeId.parse("user_01h455vb4pex5vsknk084sn02q")

Invalid inputs will result in an IllegalArgumentException, with a message explaining the cause of the parsing failure.

To parse a RawId:

val rawId: RawId = TypeId.parse("custom_01h455vb4pex5vsknk084sn02q")

Will create a RawId instance with the prefix 'custom'.

parseToValidated

If you prefer working with errors modeled as return values rather than exceptions, this is also possible (and is much more performant for untrusted input with high error rates, as no stacktrace is involved):

val userId: UserId = typeId.parseToValidated("user_01h455vb4pex5vsknk084sn02q")

when(userId) {
    is Validated.Valid -> {
        val userId = userId.id
        // Proceed with userId
    }
    is Validated.Invalid -> {
        val error = userId.error
        // Optionally, do something with the error message
    }
}

The Validated class includes a couple of functional style helper methods like filter and map.

Example:

typeId
  .parseToValidated<User>("user_01h455vb4pex5vsknk084sn02q")
  .filter { it.id == idFromSomewhereElse }
  .map { it.id }
  .ifValid { println("Valid id: $it") }

Another safe alternative for working with validated is to use Kotlin functions like:

val id = typeId.parseToValidated<User>("user_01h455vb4pex5vsknk084sn02q")
  .takeIf { it is Validated.Valid }
  ?.let { it as Validated.Valid }
  ?.id
if (id != null) {
  println("Valid id: $id")
}

These approaches are much faster when the input is untrusted and can result in lots of exceptions otherwise (see Benchmarks).

isId

Check if a string is a valid id of the given type:

val isUserId = typeId.isId<UserId>("user_01h455vb4pex5vsknk084sn02q")

Is a convenience method that uses parseToValidated and returns a boolean. It can be used to check if a string is a valid id of an expected type as it returns false if the id is valid but of a different type.

Type safety

At its base, a typeid is just a prefix followed by _ and an encoded UUID (see the spec). After it is encoded is just a string.

This could result in bugs if you accidentally mix up ids from different entities.

val id: RawId = typeId.generate("user")

// ... sometime later
val orgExists = someService.checkIfOrganizationExists(id)
// returns false most of the time so the bug may be hard to find

The library provides a type-safe way to work with these ids, by associating them with a specific type.

1. Fail if unexpected prefix is used

// fails if id does not have a `user` prefix
val userId: UserId = typeId.parse(id) 

2. Compile time safety

val id: UserId = typeId.parse(text)

// ... sometime later
val orgExists = someService.checkIfOrganizationExists(id)
// compile error, as id is of type `Id<User>` (or `UserId` if using a typealias), 
// not Id<Organization>

Customizing prefixes

The TypeId class can be customized to use a specific prefix for the generated ids associated with an entity type.

For example to register a custom prefix for the Organization entity:

val typeId = typeId().withCustomPrefix(TypedPrefix<Organization>("org"))
println(typeId.generate<Organization>()) // prints something like org_01h455vb4pex5vsknk084sn02q

Another possibility is to add the TypedPrefix annotation to the entity instance:

@TypeIdPrefix("cust")
data class Customer(override val id: CustomerId)

This can also be useful when you want a different entity interface (maybe defined in a different module). For example, define an interface with the @TypeIdPrefix annotation, which is implemented by the entity class:

@TypeIdPrefix("cust")
interface CustomerIdentifiable {
  val id: CustomerId
}

typealias CustomerId = Id<out CustomerIdentifiable>

data class Customer(override val id: CustomerId) : CustomerIdentifiable

If the @TypeIdPrefix is present (on the entity or one of its interfaces) TypeId will use that. Note that the prefixes registered through the TypeId instance will take precedence over the ones defined with annotations, you should use just one of the two methods to define prefixes.

Customizing the UUID generator

By default, the library uses the UUIDv7 generator, as per typeid specification, but you can provide your own generator.

// use Java UUID random generator
val typeId = typeId().withUUIDGenerator { UUID.randomUUID() }
// or using com.fasterxml.uuid:java-uuid-generator
val typeId = typeId().withUUIDGenerator { Generators.randomBasedGenerator().generate() }

Serialization and deserialization

The ids in this library have built-in serialization and deserialization support for Java, Kotlin (kotlinx.serialization), and Jackson.

Kotlin (kotlinx.serialization)

Both Id and RawId have @Serializable and can be used with kotlinx.serialization. You need to include the actual serialization dependency in your project.

For example, with CBOR:

include("io.github.microutils:kotlin-serialization-cbor:1.6.3")

val bytes = Cbor.encodeToByteArray<Id<User>>(id)
val deserialized = Cbor.decodeFromByteArray<Id<User>>(bytes)

Jackson

The library provides a Jackson module to serialize and deserialize Id instances.

private val objectMapper = jacksonObjectMapper().registerModule(typeId.jacksonModule())

data class UserAndOrganization(
  val user: User,
  val organization: Organization,
)

val userAndOrganization =
  UserAndOrganization(
    User(typeId.parse<User>("user_01hy0d96sgfx0rh975kqkspchh")),
    Organization(typeId.parse<Organization>("org_01hy0sk45qfmdsdme1j703yjet")),
  )
val writtenJson = objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(userAndOrganization)
// writes:
// {
//    "user" : {
//      "id" : "user_01hy0d96sgfx0rh975kqkspchh"
//    },
//    "organization" : {
//      "id" : "org_01hy0sk45qfmdsdme1j703yjet"
//    }
// }

val read = objectMapper.readValue<JsonUserAndOrganization>(writtenJson)
// read.user.id is same as typeId.parse<User>("user_01hy0d96sgfx0rh975kqkspchh")

Using it with Spring

See Spring Snippets for examples on how to use TypeId with Spring Data and WebMvc by creating converters and formatters.

Building From Source

~$ git clone https://github.com/aleris/typeid-kotlin.git
~$ cd typeid-kotling
~/typeid-kotlin sdk use java 17.0.9-tem
~/typeid-kotlin ./gradlew build

Releasing

~$ cd typeid-kotling
# Update version in build.gradle.kts
~/typeid-kotlin ./gradlew updateReadmeVersion # updates the version in README.md from build.gradle.kts
~/typeid-kotlin ./gradlew jreleaserConfig # just to double check the configuration
~/typeid-kotlin ./gradlew clean
~/typeid-kotlin ./gradlew publish
~/typeid-kotlin ./gradlew jreleaserFullRelease

Benchmarks

There is a small JMH microbenchmark included:

~/typeid-kotlin ./gradlew jmh

In a single-threaded run, all operations perform in the range of millions of calls per second, which should be enough for most use cases (used setup: Eclipse Temurin 17 JDK, 2021 MacBook Pro, run on version 1.0.0).