An idiomatic C++ client library for theDiscovery Engine API, a service that powers high-quality content recommendations on your digital properties.
While this library isGA, please note that the Google Cloud C++ client libraries donotfollowSemantic Versioning.
Quickstart
The following shows the code that you'll run in thegoogle/cloud/discoveryengine/quickstart/directory, which should give you a taste of the Discovery Engine API C++ client library API.
#include "google/cloud/discoveryengine/v1/document_client.h"
#include "google/cloud/location.h"
#include <iostream>
int main(int argc, char* argv[]) try {
if (argc != 2) {
std::cerr << "Usage: " << argv[0] << " project-id\n";
return 1;
}
auto const location = google::cloud::Location(argv[1], "global");
namespace discoveryengine = ::google::cloud::discoveryengine_v1;
auto client = discoveryengine::DocumentServiceClient(
discoveryengine::MakeDocumentServiceConnection());
auto const parent = location.FullName() +
"/dataStores/default_data_store/branches/default_branch";
for (auto d : client.ListDocuments(parent)) {
if (!d) throw std::move(d).status();
std::cout << d->DebugString() << "\n";
}
return 0;
} catch (google::cloud::Status const& status) {
std::cerr << "google::cloud::Status thrown: " << status << "\n";
return 1;
}
Main classes
This library offers multiple*Clientclasses, which are listed below. Each one of these classes exposes all the RPCs for a service as member functions of the class. This library groups multiple services because they are part of the same product or are often used together. A typical example may be the administrative and data plane operations for a single product.
The library also has other classes that provide helpers, configuration parameters, and infrastructure to mock the*Clientclasses when testing your application.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-09-04 UTC."],[[["\u003cp\u003eThis webpage details the C++ client library for the Discovery Engine API, which is designed to enhance content recommendations on digital platforms.\u003c/p\u003e\n"],["\u003cp\u003eThe library is currently in General Availability (GA) but does not adhere to Semantic Versioning.\u003c/p\u003e\n"],["\u003cp\u003eThe latest release candidate version is 2.37.0-rc, while version 2.26.0 is being viewed and a range of earlier versions are also listed.\u003c/p\u003e\n"],["\u003cp\u003eThe library provides multiple \u003ccode\u003e*Client\u003c/code\u003e classes, each with member functions for all RPCs related to a service, and is demonstrated through a quickstart code example.\u003c/p\u003e\n"],["\u003cp\u003eThe webpage also includes links to resources on error handling, endpoint overrides, authentication credential overrides, retry policies, and environment variable configurations.\u003c/p\u003e\n"]]],[],null,["Version 2.26.0keyboard_arrow_down\n\n- [2.42.0-rc (latest)](/cpp/docs/reference/discoveryengine/latest)\n- [2.41.0](/cpp/docs/reference/discoveryengine/2.41.0)\n- [2.40.0](/cpp/docs/reference/discoveryengine/2.40.0)\n- [2.39.0](/cpp/docs/reference/discoveryengine/2.39.0)\n- [2.38.0](/cpp/docs/reference/discoveryengine/2.38.0)\n- [2.37.0](/cpp/docs/reference/discoveryengine/2.37.0)\n- [2.36.0](/cpp/docs/reference/discoveryengine/2.36.0)\n- [2.35.0](/cpp/docs/reference/discoveryengine/2.35.0)\n- [2.34.0](/cpp/docs/reference/discoveryengine/2.34.0)\n- [2.33.0](/cpp/docs/reference/discoveryengine/2.33.0)\n- [2.32.0](/cpp/docs/reference/discoveryengine/2.32.0)\n- [2.31.0](/cpp/docs/reference/discoveryengine/2.31.0)\n- [2.30.0](/cpp/docs/reference/discoveryengine/2.30.0)\n- [2.29.0](/cpp/docs/reference/discoveryengine/2.29.0)\n- [2.28.0](/cpp/docs/reference/discoveryengine/2.28.0)\n- [2.27.0](/cpp/docs/reference/discoveryengine/2.27.0)\n- [2.26.0](/cpp/docs/reference/discoveryengine/2.26.0)\n- [2.25.1](/cpp/docs/reference/discoveryengine/2.25.1)\n- [2.24.0](/cpp/docs/reference/discoveryengine/2.24.0)\n- [2.23.0](/cpp/docs/reference/discoveryengine/2.23.0)\n- [2.22.1](/cpp/docs/reference/discoveryengine/2.22.1)\n- [2.21.0](/cpp/docs/reference/discoveryengine/2.21.0)\n- [2.20.0](/cpp/docs/reference/discoveryengine/2.20.0)\n- [2.19.0](/cpp/docs/reference/discoveryengine/2.19.0)\n- [2.18.0](/cpp/docs/reference/discoveryengine/2.18.0)\n- [2.17.0](/cpp/docs/reference/discoveryengine/2.17.0)\n- [2.16.0](/cpp/docs/reference/discoveryengine/2.16.0)\n- [2.15.1](/cpp/docs/reference/discoveryengine/2.15.1) \n\nDiscovery Engine API C++ Client Library\n=======================================\n\nAn idiomatic C++ client library for the [Discovery Engine API](https://cloud.google.com/discovery-engine), a service that powers high-quality content recommendations on your digital properties.\n\nWhile this library is **GA** , please note that the Google Cloud C++ client libraries do **not** follow [Semantic Versioning](https://semver.org/).\n\n### Quickstart\n\nThe following shows the code that you'll run in the `google/cloud/discoveryengine/quickstart/` directory, which should give you a taste of the Discovery Engine API C++ client library API. \n\n #include \"google/cloud/discoveryengine/v1/document_client.h\"\n #include \"google/cloud/location.h\"\n #include \u003ciostream\u003e\n\n int main(int argc, char* argv[]) try {\n if (argc != 2) {\n std::cerr \u003c\u003c \"Usage: \" \u003c\u003c argv[0] \u003c\u003c \" project-id\\n\";\n return 1;\n }\n\n auto const location = google::cloud::Location(argv[1], \"global\");\n\n namespace discoveryengine = ::google::cloud::discoveryengine_v1;\n auto client = discoveryengine::DocumentServiceClient(\n discoveryengine::MakeDocumentServiceConnection());\n\n auto const parent = location.FullName() +\n \"/dataStores/default_data_store/branches/default_branch\";\n for (auto d : client.ListDocuments(parent)) {\n if (!d) throw std::move(d).status();\n std::cout \u003c\u003c d-\u003eDebugString() \u003c\u003c \"\\n\";\n }\n\n return 0;\n } catch (google::cloud::Status const& status) {\n std::cerr \u003c\u003c \"google::cloud::Status thrown: \" \u003c\u003c status \u003c\u003c \"\\n\";\n return 1;\n }\n\n### Main classes\n\nThis library offers multiple `*Client` classes, which are listed below. Each one of these classes exposes all the RPCs for a service as member functions of the class. This library groups multiple services because they are part of the same product or are often used together. A typical example may be the administrative and data plane operations for a single product.\n\nThe library also has other classes that provide helpers, configuration parameters, and infrastructure to mock the `*Client` classes when testing your application.\n\n- [`discoveryengine_v1::CompletionServiceClient`](/cpp/docs/reference/discoveryengine/2.26.0/classgoogle_1_1cloud_1_1discoveryengine__v1_1_1CompletionServiceClient)\n- [`discoveryengine_v1::ControlServiceClient`](/cpp/docs/reference/discoveryengine/2.26.0/classgoogle_1_1cloud_1_1discoveryengine__v1_1_1ControlServiceClient)\n- [`discoveryengine_v1::ConversationalSearchServiceClient`](/cpp/docs/reference/discoveryengine/2.26.0/classgoogle_1_1cloud_1_1discoveryengine__v1_1_1ConversationalSearchServiceClient)\n- [`discoveryengine_v1::DataStoreServiceClient`](/cpp/docs/reference/discoveryengine/2.26.0/classgoogle_1_1cloud_1_1discoveryengine__v1_1_1DataStoreServiceClient)\n- [`discoveryengine_v1::DocumentServiceClient`](/cpp/docs/reference/discoveryengine/2.26.0/classgoogle_1_1cloud_1_1discoveryengine__v1_1_1DocumentServiceClient)\n- [`discoveryengine_v1::EngineServiceClient`](/cpp/docs/reference/discoveryengine/2.26.0/classgoogle_1_1cloud_1_1discoveryengine__v1_1_1EngineServiceClient)\n- [`discoveryengine_v1::GroundedGenerationServiceClient`](/cpp/docs/reference/discoveryengine/2.26.0/classgoogle_1_1cloud_1_1discoveryengine__v1_1_1GroundedGenerationServiceClient)\n- [`discoveryengine_v1::ProjectServiceClient`](/cpp/docs/reference/discoveryengine/2.26.0/classgoogle_1_1cloud_1_1discoveryengine__v1_1_1ProjectServiceClient)\n- [`discoveryengine_v1::RankServiceClient`](/cpp/docs/reference/discoveryengine/2.26.0/classgoogle_1_1cloud_1_1discoveryengine__v1_1_1RankServiceClient)\n- [`discoveryengine_v1::RecommendationServiceClient`](/cpp/docs/reference/discoveryengine/2.26.0/classgoogle_1_1cloud_1_1discoveryengine__v1_1_1RecommendationServiceClient)\n- [`discoveryengine_v1::SchemaServiceClient`](/cpp/docs/reference/discoveryengine/2.26.0/classgoogle_1_1cloud_1_1discoveryengine__v1_1_1SchemaServiceClient)\n- [`discoveryengine_v1::SearchServiceClient`](/cpp/docs/reference/discoveryengine/2.26.0/classgoogle_1_1cloud_1_1discoveryengine__v1_1_1SearchServiceClient)\n- [`discoveryengine_v1::SiteSearchEngineServiceClient`](/cpp/docs/reference/discoveryengine/2.26.0/classgoogle_1_1cloud_1_1discoveryengine__v1_1_1SiteSearchEngineServiceClient)\n- [`discoveryengine_v1::UserEventServiceClient`](/cpp/docs/reference/discoveryengine/2.26.0/classgoogle_1_1cloud_1_1discoveryengine__v1_1_1UserEventServiceClient)\n\n### More Information\n\n- [Error Handling](https://cloud.google.com/cpp/docs/reference/common/latest/common-error-handling.html) - describes how the library reports errors.\n- [How to Override the Default Endpoint](/cpp/docs/reference/discoveryengine/2.26.0/discoveryengine-override-endpoint) - describes how to override the default endpoint.\n- [How to Override the Authentication Credentials](/cpp/docs/reference/discoveryengine/2.26.0/discoveryengine-override-authentication) - describes how to change the authentication credentials used by the library.\n- [Override Retry, Backoff, and Idempotency Policies](/cpp/docs/reference/discoveryengine/2.26.0/discoveryengine-override-retry) - describes how to change the default retry policies.\n- [Environment Variables](/cpp/docs/reference/discoveryengine/2.26.0/discoveryengine-env) - describes environment variables that can configure the behavior of the library."]]