LangSmith Java SDK

The LangSmith Java SDK provides convenient access to the LangSmith REST API from applications written in Java.

To learn more about LangSmith, check out the docs.

The REST API documentation can be found on docs.smith.langchain.com. Javadocs are available on javadoc.io.

Installation

Gradle

implementation("com.langchain.smith0.1.0-alpha.23")

Maven

<dependency>
  <groupId>com.langchain.smith</groupId>
  <artifactId>langsmith-java</artifactId>
  <version>0.1.0-alpha.23</version>
</dependency>

Requirements

This library requires Java 8 or later.

Usage

import com.langchain.smith.client.LangsmithClient;
import com.langchain.smith.client.okhttp.LangsmithOkHttpClient;
import com.langchain.smith.models.runs.RunQueryParams;

// Configures using the `langchain.langsmithApiKey`, `langchain.langsmithTenantId`, `langchain.langsmithBearerToken`, `langchain.langsmithOrganizationId` and `langchain.baseUrl` system properties
// Or configures using the `LANGSMITH_API_KEY`, `LANGSMITH_TENANT_ID`, `LANGSMITH_BEARER_TOKEN`, `LANGSMITH_ORGANIZATION_ID` and `LANGSMITH_ENDPOINT` environment variables
LangsmithClient client = LangsmithOkHttpClient.fromEnv();

RunQueryParams params = RunQueryParams.builder()
    .addSession("1ffaeba7-541e-469f-bae7-df3208ea3d45")
    .limit(10L)
    .build();
var response = client.runs().query(params);

// Print runs
System.out.println("Found " + response.runs().size() + " runs:");
for (var run : response.runs()) {
    System.out.println("Run ID: " + run.id());
    System.out.println("Run Name: " + run.name());
    System.out.println("---");
}

Examples

This repository includes runnable examples in the langsmith-java-example module to help you get started.

Running Examples

Examples can be run using Gradle:

# Set required environment variables
export LANGSMITH_API_KEY="your-api-key"
export LANGSMITH_ENDPOINT="https://api.smith.langchain.com"

# Run a specific example
./gradlew run -Pexample=ListRuns

Available Examples

export LANGSMITH_PROJECT_ID="your-project-id"
./gradlew run -Pexample=ListRuns

All examples are available in langsmith-java-example.

Client configuration

Configure the client using system properties or environment variables:

import com.langchain.smith.client.LangsmithClient;
import com.langchain.smith.client.okhttp.LangsmithOkHttpClient;

// Configures using the `langchain.langsmithApiKey`, `langchain.langsmithTenantId`, `langchain.langsmithBearerToken`, `langchain.langsmithOrganizationId` and `langchain.baseUrl` system properties
// Or configures using the `LANGSMITH_API_KEY`, `LANGSMITH_TENANT_ID`, `LANGSMITH_BEARER_TOKEN`, `LANGSMITH_ORGANIZATION_ID` and `LANGSMITH_ENDPOINT` environment variables
LangsmithClient client = LangsmithOkHttpClient.fromEnv();

Or manually:

import com.langchain.smith.client.LangsmithClient;
import com.langchain.smith.client.okhttp.LangsmithOkHttpClient;

LangsmithClient client = LangsmithOkHttpClient.builder()
    .apiKey("My API Key")
    .tenantId("My Tenant ID")
    .organizationId("My Organization ID")
    .build();

Or using a combination of the two approaches:

import com.langchain.smith.client.LangsmithClient;
import com.langchain.smith.client.okhttp.LangsmithOkHttpClient;

LangsmithClient client = LangsmithOkHttpClient.builder()
    // Configures using the `langchain.langsmithApiKey`, `langchain.langsmithTenantId`, `langchain.langsmithBearerToken`, `langchain.langsmithOrganizationId` and `langchain.baseUrl` system properties
    // Or configures using the `LANGSMITH_API_KEY`, `LANGSMITH_TENANT_ID`, `LANGSMITH_BEARER_TOKEN`, `LANGSMITH_ORGANIZATION_ID` and `LANGSMITH_ENDPOINT` environment variables
    .fromEnv()
    .apiKey("My API Key")
    .build();

See this table for the available options:

Setter	System property	Environment variable	Required	Default value
apiKey	langchain.langsmithApiKey	LANGSMITH_API_KEY	false	-
tenantId	langchain.langsmithTenantId	LANGSMITH_TENANT_ID	false	-
bearerToken	langchain.langsmithBearerToken	LANGSMITH_BEARER_TOKEN	false	-
organizationId	langchain.langsmithOrganizationId	LANGSMITH_ORGANIZATION_ID	false	-
baseUrl	langchain.baseUrl	LANGSMITH_ENDPOINT	true	"https://api.smith.langchain.com/"

System properties take precedence over environment variables.

[!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.

Modifying configuration

To temporarily use a modified client configuration, while reusing the same connection and thread pools, call withOptions() on any client or service:

import com.langchain.smith.client.LangsmithClient;

LangsmithClient clientWithOptions = client.withOptions(optionsBuilder -> {
    optionsBuilder.baseUrl("https://example.com");
    optionsBuilder.maxRetries(42);
});

The withOptions() method does not affect the original client or service.

Requests and responses

To send a request to the LangChain 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 Java class.

For example, client.sessions().dashboard(...) should be called with an instance of SessionDashboardParams, and it will return an instance of CustomChartsSection.

Immutability

Each class in the SDK has an associated builder or factory method for constructing it.

Each class is immutable once constructed. If the class has an associated builder, then it has a toBuilder() method, which can be used to convert it back to a builder for making a modified copy.

Because each class is immutable, builder modification will never affect already built class instances.

Asynchronous execution

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

import com.langchain.smith.client.LangsmithClient;
import com.langchain.smith.client.okhttp.LangsmithOkHttpClient;
import com.langchain.smith.models.sessions.CustomChartsSection;
import com.langchain.smith.models.sessions.CustomChartsSectionRequest;
import com.langchain.smith.models.sessions.SessionDashboardParams;
import java.util.concurrent.CompletableFuture;

// Configures using the `langchain.langsmithApiKey`, `langchain.langsmithTenantId`, `langchain.langsmithBearerToken`, `langchain.langsmithOrganizationId` and `langchain.baseUrl` system properties
// Or configures using the `LANGSMITH_API_KEY`, `LANGSMITH_TENANT_ID`, `LANGSMITH_BEARER_TOKEN`, `LANGSMITH_ORGANIZATION_ID` and `LANGSMITH_ENDPOINT` environment variables
LangsmithClient client = LangsmithOkHttpClient.fromEnv();

SessionDashboardParams params = SessionDashboardParams.builder()
    .sessionId("1ffaeba7-541e-469f-bae7-df3208ea3d45")
    .customChartsSectionRequest(CustomChartsSectionRequest.builder().build())
    .build();
CompletableFuture<CustomChartsSection> customChartsSection = client.async().sessions().dashboard(params);

Or create an asynchronous client from the beginning:

import com.langchain.smith.client.LangsmithClientAsync;
import com.langchain.smith.client.okhttp.LangsmithOkHttpClientAsync;
import com.langchain.smith.models.sessions.CustomChartsSection;
import com.langchain.smith.models.sessions.CustomChartsSectionRequest;
import com.langchain.smith.models.sessions.SessionDashboardParams;
import java.util.concurrent.CompletableFuture;

// Configures using the `langchain.langsmithApiKey`, `langchain.langsmithTenantId`, `langchain.langsmithBearerToken`, `langchain.langsmithOrganizationId` and `langchain.baseUrl` system properties
// Or configures using the `LANGSMITH_API_KEY`, `LANGSMITH_TENANT_ID`, `LANGSMITH_BEARER_TOKEN`, `LANGSMITH_ORGANIZATION_ID` and `LANGSMITH_ENDPOINT` environment variables
LangsmithClientAsync client = LangsmithOkHttpClientAsync.fromEnv();

SessionDashboardParams params = SessionDashboardParams.builder()
    .sessionId("1ffaeba7-541e-469f-bae7-df3208ea3d45")
    .customChartsSectionRequest(CustomChartsSectionRequest.builder().build())
    .build();
CompletableFuture<CustomChartsSection> customChartsSection = client.sessions().dashboard(params);

The asynchronous client supports the same options as the synchronous one, except most methods return CompletableFutures.

File uploads

The SDK defines methods that accept files.

To upload a file, pass a Path:

import com.langchain.smith.models.examples.Example;
import com.langchain.smith.models.examples.ExampleUploadFromCsvParams;
import java.nio.file.Paths;

ExampleUploadFromCsvParams params = ExampleUploadFromCsvParams.builder()
    .datasetId("182bd5e5-6e1a-4fe4-a799-aa6d9a6ab26e")
    .addInputKey("string")
    .file(Paths.get("/path/to/file"))
    .build();
List<Example> examples = client.examples().uploadFromCsv(params);

Or an arbitrary InputStream:

import com.langchain.smith.models.examples.Example;
import com.langchain.smith.models.examples.ExampleUploadFromCsvParams;
import java.net.URL;

ExampleUploadFromCsvParams params = ExampleUploadFromCsvParams.builder()
    .datasetId("182bd5e5-6e1a-4fe4-a799-aa6d9a6ab26e")
    .addInputKey("string")
    .file(new URL("https://example.com//path/to/file").openStream())
    .build();
List<Example> examples = client.examples().uploadFromCsv(params);

Or a byte[] array:

import com.langchain.smith.models.examples.Example;
import com.langchain.smith.models.examples.ExampleUploadFromCsvParams;

ExampleUploadFromCsvParams params = ExampleUploadFromCsvParams.builder()
    .datasetId("182bd5e5-6e1a-4fe4-a799-aa6d9a6ab26e")
    .addInputKey("string")
    .file("content".getBytes())
    .build();
List<Example> examples = client.examples().uploadFromCsv(params);

Note that when passing a non-Path its filename is unknown so it will not be included in the request. To manually set a filename, pass a MultipartField:

import com.langchain.smith.core.MultipartField;
import com.langchain.smith.models.examples.Example;
import com.langchain.smith.models.examples.ExampleUploadFromCsvParams;
import java.io.InputStream;
import java.net.URL;

ExampleUploadFromCsvParams params = ExampleUploadFromCsvParams.builder()
    .datasetId("182bd5e5-6e1a-4fe4-a799-aa6d9a6ab26e")
    .addInputKey("string")
    .file(MultipartField.<InputStream>builder()
        .value(new URL("https://example.com//path/to/file").openStream())
        .filename("/path/to/file")
        .build())
    .build();
List<Example> examples = client.examples().uploadFromCsv(params);

Raw responses

The SDK defines methods that deserialize responses into instances of Java classes. However, these methods don't provide access to the response headers, status code, or the raw response body.

To access this data, prefix any HTTP method call on a client or service with withRawResponse():

import com.langchain.smith.core.http.Headers;
import com.langchain.smith.core.http.HttpResponseFor;
import com.langchain.smith.models.sessions.CustomChartsSection;
import com.langchain.smith.models.sessions.CustomChartsSectionRequest;
import com.langchain.smith.models.sessions.SessionDashboardParams;

SessionDashboardParams params = SessionDashboardParams.builder()
    .sessionId("1ffaeba7-541e-469f-bae7-df3208ea3d45")
    .customChartsSectionRequest(CustomChartsSectionRequest.builder().build())
    .build();
HttpResponseFor<CustomChartsSection> customChartsSection = client.sessions().withRawResponse().dashboard(params);

int statusCode = customChartsSection.statusCode();
Headers headers = customChartsSection.headers();

You can still deserialize the response into an instance of a Java class if needed:

import com.langchain.smith.models.sessions.CustomChartsSection;

CustomChartsSection parsedCustomChartsSection = customChartsSection.parse();

Error handling

The SDK throws custom unchecked exception types:

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

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

• LangChainIoException: I/O networking errors.

• LangChainRetryableException: Generic error indicating a failure that could be retried by the client.

• LangChainInvalidDataException: 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.

• LangChainException: 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

The SDK defines methods that return a paginated lists of results. It provides convenient ways to 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, use the autoPager() method, which automatically fetches more pages as needed.

When using the synchronous client, the method returns an Iterable

import com.langchain.smith.models.datasets.Dataset;
import com.langchain.smith.models.datasets.DatasetListPage;

DatasetListPage page = client.datasets().list();

// Process as an Iterable
for (Dataset dataset : page.autoPager()) {
    System.out.println(dataset);
}

// Process as a Stream
page.autoPager()
    .stream()
    .limit(50)
    .forEach(dataset -> System.out.println(dataset));

When using the asynchronous client, the method returns an AsyncStreamResponse:

import com.langchain.smith.core.http.AsyncStreamResponse;
import com.langchain.smith.models.datasets.Dataset;
import com.langchain.smith.models.datasets.DatasetListPageAsync;
import java.util.Optional;
import java.util.concurrent.CompletableFuture;

CompletableFuture<DatasetListPageAsync> pageFuture = client.async().datasets().list();

pageFuture.thenRun(page -> page.autoPager().subscribe(dataset -> {
    System.out.println(dataset);
}));

// If you need to handle errors or completion of the stream
pageFuture.thenRun(page -> page.autoPager().subscribe(new AsyncStreamResponse.Handler<>() {
    @Override
    public void onNext(Dataset dataset) {
        System.out.println(dataset);
    }

    @Override
    public void onComplete(Optional<Throwable> error) {
        if (error.isPresent()) {
            System.out.println("Something went wrong!");
            throw new RuntimeException(error.get());
        } else {
            System.out.println("No more!");
        }
    }
}));

// Or use futures
pageFuture.thenRun(page -> page.autoPager()
    .subscribe(dataset -> {
        System.out.println(dataset);
    })
    .onCompleteFuture()
    .whenComplete((unused, error) -> {
        if (error != null) {
            System.out.println("Something went wrong!");
            throw new RuntimeException(error);
        } else {
            System.out.println("No more!");
        }
    }));

Manual pagination

To access individual page items and manually request the next page, use the items(), hasNextPage(), and nextPage() methods:

import com.langchain.smith.models.datasets.Dataset;
import com.langchain.smith.models.datasets.DatasetListPage;

DatasetListPage page = client.datasets().list();
while (true) {
    for (Dataset dataset : page.items()) {
        System.out.println(dataset);
    }

    if (!page.hasNextPage()) {
        break;
    }

    page = page.nextPage();
}

Logging

The SDK uses the standard OkHttp logging interceptor.

Enable logging by setting the LANGCHAIN_LOG environment variable to info:

export LANGCHAIN_LOG=info

Or to debug for more verbose logging:

export LANGCHAIN_LOG=debug

ProGuard and R8

Although the SDK uses reflection, it is still usable with ProGuard and R8 because langsmith-java-core is published with a configuration file containing keep rules.

ProGuard and R8 should automatically detect and use the published rules, but you can also manually copy the keep rules if necessary.

Jackson

The SDK depends on Jackson for JSON serialization/deserialization. It is compatible with version 2.13.4 or higher, but depends on version 2.18.2 by default.

The SDK throws an exception if it detects an incompatible Jackson version at runtime (e.g. if the default version was overridden in your Maven or Gradle config).

If the SDK threw an exception, but you're certain the version is compatible, then disable the version check using the checkJacksonVersionCompatibility on LangsmithOkHttpClient or LangsmithOkHttpClientAsync.

[!CAUTION] We make no guarantee that the SDK works correctly when the Jackson version check is disabled.

Also note that there are bugs in older Jackson versions that can affect the SDK. We don't work around all Jackson bugs (example) and expect users to upgrade Jackson for those instead.

Network options

Retries

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

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 request.

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

import com.langchain.smith.client.LangsmithClient;
import com.langchain.smith.client.okhttp.LangsmithOkHttpClient;

LangsmithClient client = LangsmithOkHttpClient.builder()
    .fromEnv()
    .maxRetries(4)
    .build();

Timeouts

Requests time out after 90 seconds by default.

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

import com.langchain.smith.models.sessions.CustomChartsSection;

CustomChartsSection customChartsSection = client.sessions().dashboard(
  params, RequestOptions.builder().timeout(Duration.ofSeconds(30)).build()
);

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

import com.langchain.smith.client.LangsmithClient;
import com.langchain.smith.client.okhttp.LangsmithOkHttpClient;
import java.time.Duration;

LangsmithClient client = LangsmithOkHttpClient.builder()
    .fromEnv()
    .timeout(Duration.ofSeconds(30))
    .build();

Proxies

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

import com.langchain.smith.client.LangsmithClient;
import com.langchain.smith.client.okhttp.LangsmithOkHttpClient;
import java.net.InetSocketAddress;
import java.net.Proxy;

LangsmithClient client = LangsmithOkHttpClient.builder()
    .fromEnv()
    .proxy(new Proxy(
      Proxy.Type.HTTP, new InetSocketAddress(
        "https://example.com", 8080
      )
    ))
    .build();

Connection pooling

To customize the underlying OkHttp connection pool, configure the client using the maxIdleConnections and keepAliveDuration methods:

import com.langchain.smith.client.LangsmithClient;
import com.langchain.smith.client.okhttp.LangsmithOkHttpClient;
import java.time.Duration;

LangsmithClient client = LangsmithOkHttpClient.builder()
    .fromEnv()
    // If `maxIdleConnections` is set, then `keepAliveDuration` must be set, and vice versa.
    .maxIdleConnections(10)
    .keepAliveDuration(Duration.ofMinutes(2))
    .build();

If both options are unset, OkHttp's default connection pool settings are used.

HTTPS

[!NOTE] Most applications should not call these methods, and instead use the system defaults. The defaults include special optimizations that can be lost if the implementations are modified.

To configure how HTTPS connections are secured, configure the client using the sslSocketFactory, trustManager, and hostnameVerifier methods:

import com.langchain.smith.client.LangsmithClient;
import com.langchain.smith.client.okhttp.LangsmithOkHttpClient;

LangsmithClient client = LangsmithOkHttpClient.builder()
    .fromEnv()
    // If `sslSocketFactory` is set, then `trustManager` must be set, and vice versa.
    .sslSocketFactory(yourSSLSocketFactory)
    .trustManager(yourTrustManager)
    .hostnameVerifier(yourHostnameVerifier)
    .build();

Custom HTTP client

The SDK consists of three artifacts:

• langsmith-java-core
  • Contains core SDK logic
  • Does not depend on OkHttp
  • Exposes LangsmithClient, LangsmithClientAsync, LangsmithClientImpl, and LangsmithClientAsyncImpl, all of which can work with any HTTP client
• langsmith-java-client-okhttp
  • Depends on OkHttp
  • Exposes LangsmithOkHttpClient and LangsmithOkHttpClientAsync, which provide a way to construct LangsmithClientImpl and LangsmithClientAsyncImpl, respectively, using OkHttp
• langsmith-java
  • Depends on and exposes the APIs of both langsmith-java-core and langsmith-java-client-okhttp
  • Does not have its own logic

This structure allows replacing the SDK's default HTTP client without pulling in unnecessary dependencies.

Customized OkHttpClient

[!TIP] Try the available network options before replacing the default client.

To use a customized OkHttpClient:

1. Replace your langsmith-java dependency with langsmith-java-core
2. Copy langsmith-java-client-okhttp's OkHttpClient class into your code and customize it
3. Construct LangsmithClientImpl or LangsmithClientAsyncImpl, similarly to LangsmithOkHttpClient or LangsmithOkHttpClientAsync, using your customized client

Completely custom HTTP client

To use a completely custom HTTP client:

1. Replace your langsmith-java dependency with langsmith-java-core
2. Write a class that implements the HttpClient interface
3. Construct LangsmithClientImpl or LangsmithClientAsyncImpl, similarly to LangsmithOkHttpClient or LangsmithOkHttpClientAsync, using your new client class

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.langchain.smith.core.JsonValue;
import com.langchain.smith.models.sessions.SessionDashboardParams;

SessionDashboardParams params = SessionDashboardParams.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.

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

import com.langchain.smith.models.sessions.CustomChartsSectionRequest;
import com.langchain.smith.models.sessions.SessionDashboardParams;

SessionDashboardParams params = SessionDashboardParams.builder()
    .customChartsSectionRequest(CustomChartsSectionRequest.builder().build())
    .build();

The most straightforward way to create a JsonValue is using its from(...) method:

import com.langchain.smith.core.JsonValue;
import java.util.List;
import java.util.Map;

// Create primitive JSON values
JsonValue nullValue = JsonValue.from(null);
JsonValue booleanValue = JsonValue.from(true);
JsonValue numberValue = JsonValue.from(42);
JsonValue stringValue = JsonValue.from("Hello World!");

// Create a JSON array value equivalent to `["Hello", "World"]`
JsonValue arrayValue = JsonValue.from(List.of(
  "Hello", "World"
));

// Create a JSON object value equivalent to `{ "a": 1, "b": 2 }`
JsonValue objectValue = JsonValue.from(Map.of(
  "a", 1,
  "b", 2
));

// Create an arbitrarily nested JSON equivalent to:
// {
//   "a": [1, 2],
//   "b": [3, 4]
// }
JsonValue complexValue = JsonValue.from(Map.of(
  "a", List.of(
    1, 2
  ),
  "b", List.of(
    3, 4
  )
));

Normally a Builder class's build method will throw IllegalStateException if any required parameter or property is unset.

To forcibly omit a required parameter or property, pass JsonMissing:

import com.langchain.smith.core.JsonMissing;
import com.langchain.smith.models.sessions.CustomChartsSectionRequest;
import com.langchain.smith.models.sessions.SessionDashboardParams;

SessionDashboardParams params = SessionDashboardParams.builder()
    .customChartsSectionRequest(CustomChartsSectionRequest.builder().build())
    .sessionId(JsonMissing.of())
    .build();

Response properties

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

import com.langchain.smith.core.JsonValue;
import java.util.Map;

Map<String, JsonValue> additionalProperties = client.sessions().dashboard(params)._additionalProperties();
JsonValue secretPropertyValue = additionalProperties.get("secretProperty");

String result = secretPropertyValue.accept(new JsonValue.Visitor<>() {
    @Override
    public String visitNull() {
        return "It's null!";
    }

    @Override
    public String visitBoolean(boolean value) {
        return "It's a boolean!";
    }

    @Override
    public String visitNumber(Number value) {
        return "It's a number!";
    }

    // Other methods include `visitMissing`, `visitString`, `visitArray`, and `visitObject`
    // The default implementation of each unimplemented method delegates to `visitDefault`, which throws by default, but can also be overridden
});

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

import com.langchain.smith.core.JsonField;
import java.util.Optional;

JsonField<Object> field = client.sessions().dashboard(params)._field();

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

  // Try to deserialize into a custom type
  MyClass myObject = field.asUnknown().orElseThrow().convert(MyClass.class);
}

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 LangChainInvalidDataException 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.langchain.smith.models.sessions.CustomChartsSection;

CustomChartsSection customChartsSection = client.sessions().dashboard(params).validate();

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

import com.langchain.smith.models.sessions.CustomChartsSection;

CustomChartsSection customChartsSection = client.sessions().dashboard(
  params, RequestOptions.builder().responseValidation(true).build()
);

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

import com.langchain.smith.client.LangsmithClient;
import com.langchain.smith.client.okhttp.LangsmithOkHttpClient;

LangsmithClient client = LangsmithOkHttpClient.builder()
    .fromEnv()
    .responseValidation(true)
    .build();

FAQ

Why don't you use plain enum classes?

Java enum classes are not trivially forwards compatible. Using them in the SDK could cause runtime exceptions if the API is updated to respond with a new enum value.

Why do you represent fields using JsonField<T> instead of just plain T?

Using JsonField<T> enables a few features:

• Allowing usage of undocumented API functionality
• Lazily validating the API response against the expected shape
• Representing absent vs explicitly null values

Why don't you use data classes?

It is not backwards compatible to add new fields to a data class and we don't want to introduce a breaking change every time we add a field to a class.

Why don't you use checked exceptions?

Checked exceptions are widely considered a mistake in the Java programming language. In fact, they were omitted from Kotlin for this reason.

Checked exceptions:

• Are verbose to handle
• Encourage error handling at the wrong level of abstraction, where nothing can be done about the error
• Are tedious to propagate due to the function coloring problem
• Don't play well with lambdas (also due to the function coloring problem)

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.