Modern Treasury Kotlin API Library

The Modern Treasury Kotlin SDK provides convenient access to the Modern Treasury REST API from applications written in Kotlin.

The Modern Treasury Kotlin SDK is similar to the Modern Treasury Java SDK but with minor differences that make it more ergonomic for use in Kotlin, such as nullable values instead of Optional, Sequence instead of Stream, and suspend functions instead of CompletableFuture.

The REST API documentation can be found on docs.moderntreasury.com.

Installation

Gradle

implementation("com.moderntreasury:modern-treasury-kotlin:5.0.0")

Maven

<dependency>
    <groupId>com.moderntreasury</groupId>
    <artifactId>modern-treasury-kotlin</artifactId>
    <version>5.0.0</version>
</dependency>

Requirements

This library requires Java 8 or later.

Usage

import com.moderntreasury.api.client.ModernTreasuryClient
import com.moderntreasury.api.client.okhttp.ModernTreasuryOkHttpClient
import com.moderntreasury.api.models.Counterparty
import com.moderntreasury.api.models.CounterpartyCreateParams

// Configures using the `MODERN_TREASURY_API_KEY`, `MODERN_TREASURY_ORGANIZATION_ID` and `MODERN_TREASURY_WEBHOOK_KEY` environment variables
val client: ModernTreasuryClient = ModernTreasuryOkHttpClient.fromEnv()

val params: CounterpartyCreateParams = CounterpartyCreateParams.builder()
    .name("my first counterparty")
    .build()
val counterparty: Counterparty = client.counterparties().create(params)

Client configuration

Configure the client using environment variables:

import com.moderntreasury.api.client.ModernTreasuryClient
import com.moderntreasury.api.client.okhttp.ModernTreasuryOkHttpClient

// Configures using the `MODERN_TREASURY_API_KEY`, `MODERN_TREASURY_ORGANIZATION_ID` and `MODERN_TREASURY_WEBHOOK_KEY` environment variables
val client: ModernTreasuryClient = ModernTreasuryOkHttpClient.fromEnv()

Or manually:

import com.moderntreasury.api.client.ModernTreasuryClient
import com.moderntreasury.api.client.okhttp.ModernTreasuryOkHttpClient

val client: ModernTreasuryClient = ModernTreasuryOkHttpClient.builder()
    .apiKey("My API Key")
    .organizationId("my-organization-ID")
    .build()

Or using a combination of the two approaches:

import com.moderntreasury.api.client.ModernTreasuryClient
import com.moderntreasury.api.client.okhttp.ModernTreasuryOkHttpClient

val client: ModernTreasuryClient = ModernTreasuryOkHttpClient.builder()
    // Configures using the `MODERN_TREASURY_API_KEY`, `MODERN_TREASURY_ORGANIZATION_ID` and `MODERN_TREASURY_WEBHOOK_KEY` environment variables
    .fromEnv()
    .apiKey("My API Key")
    .build()

See this table for the available options:

Setter	Environment variable	Required	Default value
apiKey	MODERN_TREASURY_API_KEY	true	-
organizationId	MODERN_TREASURY_ORGANIZATION_ID	true	-
webhookKey	MODERN_TREASURY_WEBHOOK_KEY	false	-

Tip

Don't create more than one client in the same application. Each client has a connection pool and thread pools, which are more efficient to share between requests.

Requests and responses

To send a request to the Modern Treasury API, build an instance of some Params class and pass it to the corresponding client method. When the response is received, it will be deserialized into an instance of a Kotlin class.

For example, client.counterparties().create(...) should be called with an instance of CounterpartyCreateParams, and it will return an instance of Counterparty.

Asynchronous execution

The default client is synchronous. To switch to asynchronous execution, call the async() method:

import com.moderntreasury.api.client.ModernTreasuryClient
import com.moderntreasury.api.client.okhttp.ModernTreasuryOkHttpClient
import com.moderntreasury.api.models.Counterparty
import com.moderntreasury.api.models.CounterpartyCreateParams

// Configures using the `MODERN_TREASURY_API_KEY`, `MODERN_TREASURY_ORGANIZATION_ID` and `MODERN_TREASURY_WEBHOOK_KEY` environment variables
val client: ModernTreasuryClient = ModernTreasuryOkHttpClient.fromEnv()

val params: CounterpartyCreateParams = CounterpartyCreateParams.builder()
    .name("my first counterparty")
    .build()
val counterparty: Counterparty = client.async().counterparties().create(params)

Or create an asynchronous client from the beginning:

import com.moderntreasury.api.client.ModernTreasuryClientAsync
import com.moderntreasury.api.client.okhttp.ModernTreasuryOkHttpClientAsync
import com.moderntreasury.api.models.Counterparty
import com.moderntreasury.api.models.CounterpartyCreateParams

// Configures using the `MODERN_TREASURY_API_KEY`, `MODERN_TREASURY_ORGANIZATION_ID` and `MODERN_TREASURY_WEBHOOK_KEY` environment variables
val client: ModernTreasuryClientAsync = ModernTreasuryOkHttpClientAsync.fromEnv()

val params: CounterpartyCreateParams = CounterpartyCreateParams.builder()
    .name("my first counterparty")
    .build()
val counterparty: Counterparty = client.counterparties().create(params)

The asynchronous client supports the same options as the synchronous one, except most methods are suspending.

Error handling

The SDK throws custom unchecked exception types:

• ModernTreasuryServiceException: Base class for HTTP errors. See this table for which exception subclass is thrown for each HTTP status code:

  Status	Exception
  400	BadRequestException
  401	AuthenticationException
  403	PermissionDeniedException
  404	NotFoundException
  422	UnprocessableEntityException
  429	RateLimitException
  5xx	InternalServerException
  others	UnexpectedStatusCodeException

• ModernTreasuryIoException: I/O networking errors.

• ModernTreasuryInvalidDataException: Failure to interpret successfully parsed data. For example, when accessing a property that's supposed to be required, but the API unexpectedly omitted it from the response.

• ModernTreasuryException: Base class for all exceptions. Most errors will result in one of the previously mentioned ones, but completely generic errors may be thrown using the base class.

Pagination

For methods that return a paginated list of results, this library provides convenient ways access the results either one page at a time, or item-by-item across all pages.

Auto-pagination

To iterate through all results across all pages, you can use autoPager, which automatically handles fetching more pages for you:

Synchronous

import com.moderntreasury.api.models.Counterparty
import com.moderntreasury.api.models.CounterpartyListPage

// As a Sequence:
client.counterparties().list(params).autoPager()
    .take(50)
    .forEach { counterparty -> print(counterparty) }

Asynchronous

// As a Flow:
asyncClient.counterparties().list(params).autoPager()
    .take(50)
    .collect { counterparty -> print(counterparty) }

Manual pagination

If none of the above helpers meet your needs, you can also manually request pages one-by-one. A page of results has a data() method to fetch the list of objects, as well as top-level response and other methods to fetch top-level data about the page. It also has methods hasNextPage, getNextPage, and getNextPageParams methods to help with pagination.

import com.moderntreasury.api.models.Counterparty
import com.moderntreasury.api.models.CounterpartyListPage

val page = client.counterparties().list(params)
while (page != null) {
    for (counterparty in page.items) {
        print(counterparty)
    }

    page = page.getNextPage()
}

Logging

The SDK uses the standard OkHttp logging interceptor.

Enable logging by setting the MODERN_TREASURY_LOG environment variable to info:

$ export MODERN_TREASURY_LOG=info

Or to debug for more verbose logging:

$ export MODERN_TREASURY_LOG=debug

Network options

Retries

The SDK automatically retries 2 times by default, with a short exponential backoff.

Only the following error types are retried:

• Connection errors (for example, due to a network connectivity problem)
• 408 Request Timeout
• 409 Conflict
• 429 Rate Limit
• 5xx Internal

The API may also explicitly instruct the SDK to retry or not retry a response.

To set a custom number of retries, configure the client using the maxRetries method:

import com.moderntreasury.api.client.ModernTreasuryClient
import com.moderntreasury.api.client.okhttp.ModernTreasuryOkHttpClient

val client: ModernTreasuryClient = ModernTreasuryOkHttpClient.builder()
    .fromEnv()
    .maxRetries(4)
    .build()

Timeouts

Requests time out after 1 minute by default.

To set a custom timeout, configure the method call using the timeout method:

import com.moderntreasury.api.models.Counterparty
import com.moderntreasury.api.models.CounterpartyCreateParams

val counterparty: Counterparty = client.counterparties().create(
  params, RequestOptions.builder().timeout(Duration.ofSeconds(30)).build()
)

Or configure the default for all method calls at the client level:

import com.moderntreasury.api.client.ModernTreasuryClient
import com.moderntreasury.api.client.okhttp.ModernTreasuryOkHttpClient
import java.time.Duration

val client: ModernTreasuryClient = ModernTreasuryOkHttpClient.builder()
    .fromEnv()
    .timeout(Duration.ofSeconds(30))
    .build()

Proxies

To route requests through a proxy, configure the client using the proxy method:

import com.moderntreasury.api.client.ModernTreasuryClient
import com.moderntreasury.api.client.okhttp.ModernTreasuryOkHttpClient
import java.net.InetSocketAddress
import java.net.Proxy

val client: ModernTreasuryClient = ModernTreasuryOkHttpClient.builder()
    .fromEnv()
    .proxy(Proxy(
      Proxy.Type.HTTP, InetSocketAddress(
        "https://example.com", 8080
      )
    ))
    .build()

Undocumented API functionality

The SDK is typed for convenient usage of the documented API. However, it also supports working with undocumented or not yet supported parts of the API.

Parameters

To set undocumented parameters, call the putAdditionalHeader, putAdditionalQueryParam, or putAdditionalBodyProperty methods on any Params class:

import com.moderntreasury.api.core.JsonValue
import com.moderntreasury.api.models.CounterpartyCreateParams

val params: CounterpartyCreateParams = CounterpartyCreateParams.builder()
    .putAdditionalHeader("Secret-Header", "42")
    .putAdditionalQueryParam("secret_query_param", "42")
    .putAdditionalBodyProperty("secretProperty", JsonValue.from("42"))
    .build()

These can be accessed on the built object later using the _additionalHeaders(), _additionalQueryParams(), and _additionalBodyProperties() methods. You can also set undocumented parameters on nested headers, query params, or body classes using the putAdditionalProperty method. These properties can be accessed on the built object later using the _additionalProperties() method.

To set a documented parameter or property to an undocumented or not yet supported value, pass a JsonValue object to its setter:

import com.moderntreasury.api.core.JsonValue
import com.moderntreasury.api.models.CounterpartyCreateParams

val params: CounterpartyCreateParams = CounterpartyCreateParams.builder()
    .name(JsonValue.from(42))
    .build()

Response properties

To access undocumented response properties, call the _additionalProperties() method:

import com.moderntreasury.api.core.JsonBoolean
import com.moderntreasury.api.core.JsonNull
import com.moderntreasury.api.core.JsonNumber
import com.moderntreasury.api.core.JsonValue

val additionalProperties: Map<String, JsonValue> = client.counterparties().create(params)._additionalProperties()
val secretPropertyValue: JsonValue = additionalProperties.get("secretProperty")

val result = when (secretPropertyValue) {
    is JsonNull -> "It's null!"
    is JsonBoolean -> "It's a boolean!"
    is JsonNumber -> "It's a number!"
    // Other types include `JsonMissing`, `JsonString`, `JsonArray`, and `JsonObject`
    else -> "It's something else!"
}

To access a property's raw JSON value, which may be undocumented, call its _ prefixed method:

import com.moderntreasury.api.core.JsonField

val name: JsonField<String> = client.counterparties().create(params)._name()

if (name.isMissing()) {
  // The property is absent from the JSON response
} else if (name.isNull()) {
  // The property was set to literal null
} else {
  // Check if value was provided as a string
  // Other methods include `asNumber()`, `asBoolean()`, etc.
  val jsonString: String? = name.asString();

  // Try to deserialize into a custom type
  val myObject: MyClass = name.asUnknown()!!.convert(MyClass::class.java)
}

Response validation

In rare cases, the API may return a response that doesn't match the expected type. For example, the SDK may expect a property to contain a String, but the API could return something else.

By default, the SDK will not throw an exception in this case. It will throw ModernTreasuryInvalidDataException only if you directly access the property.

If you would prefer to check that the response is completely well-typed upfront, then either call validate():

import com.moderntreasury.api.models.Counterparty

val counterparty: Counterparty = client.counterparties().create(params).validate()

Or configure the method call to validate the response using the responseValidation method:

import com.moderntreasury.api.models.Counterparty
import com.moderntreasury.api.models.CounterpartyCreateParams

val counterparty: Counterparty = client.counterparties().create(
  params, RequestOptions.builder().responseValidation(true).build()
)

Or configure the default for all method calls at the client level:

import com.moderntreasury.api.client.ModernTreasuryClient
import com.moderntreasury.api.client.okhttp.ModernTreasuryOkHttpClient

val client: ModernTreasuryClient = ModernTreasuryOkHttpClient.builder()
    .fromEnv()
    .responseValidation(true)
    .build()

Semantic versioning

This package generally follows SemVer conventions, though certain backwards-incompatible changes may be released as minor versions:

1. Changes to library internals which are technically public but not intended or documented for external use. (Please open a GitHub issue to let us know if you are relying on such internals.)
2. Changes that we do not expect to impact the vast majority of users in practice.

We take backwards-compatibility seriously and work hard to ensure you can rely on a smooth upgrade experience.

We are keen for your feedback; please open an issue with questions, bugs, or suggestions.