C++ Boost.Beast client generator with OpenAPI 3.1 support by bold84 · Pull Request #24335 · OpenAPITools/openapi-generator

bold84 · 2026-07-17T13:00:04Z

C++ Boost.Beast Client Code Generator (with OpenAPI 3.1 support)

This continues the work from PR #20971 by @cwilson1776, which itself was a resurrection of the original PR #12197 by @LukasWoodtli.

Credits

@LukasWoodtli did the original work creating the Boost.Beast client generator in PR Cpp boost beast client #12197
@cwilson1776 resurrected it in PR Cpp boost beast client redux #20971, fixing bitrot, updating for modern Boost/OpenSSL, and adding integration tests with imposter mock server
This PR builds on their work with the additions below

What this PR adds on top of #20971

OpenAPI 3.1 support (needed to generate clients from modern specs like the OpenAI API):

Use ModelUtils.getType() for proper OpenAPI 3.1 type detection (including type: "null")
Map free-form objects to boost::property_tree::ptree
Set correct default values for boost::property_tree::ptree properties
Add AnyType.h supporting file for OpenAPI 3.1 any-type schemas
Register cpp-boost-beast-client in CodegenConfig service loader

Modern Boost/OpenSSL fixes:

Update CMakeLists.txt template for modern Boost/OpenSSL find patterns
Fix map serialization in model templates
Fix AnyType.h template with proper include guard and namespace

Core generator warning fixes:

DefaultCodegen: Populate _enum, isEnum, isInnerEnum for referenced enum schemas so enumName is properly computed, fixing Could not compute datatypeWithEnum warnings for array items referencing enum schemas
DefaultCodegen: Replace spurious Could not compute datatypeWithEnum warning with silent fallback for non-enum array items
DefaultGenerator: Set operationId from webhook key for webhook operations missing operationId, fixing Empty operationId found for path warnings
DefaultGenerator: Tag untagged webhook operations with Webhooks instead of default, fixing Duplicate file path detected collision with DefaultApi
ExamplesUtils: Downgrade No application/json content media type from warn to debug for valid non-JSON responses (e.g. application/octet-stream)

Motivation

A C++ client generator that:

Does not depend on the now-retired cpprestsdk
Does not require an X server (unlike the Qt client generator)
Supports OpenAPI 3.1 specs (needed for modern APIs like OpenAI)

Build and test

sudo apt update && sudo apt install libboost-all-dev cmake
curl -L https://raw.githubusercontent.com/imposter-project/imposter-cli/main/install/install_imposter.sh | sudo bash -
cd samples/client/petstore/cpp-boost-beast/
./build-and-test.bash

PR checklist

Read the contribution guidelines
Pull Request title clearly describes the work
Built the project: ./mvnw clean package
File the PR against the master branch
@mention the technical committee members

@ravinikam
@stkrwork
@etherealjoy
@MartinDelille
@muttleyxd

Summary by cubic

Adds cpp-boost-beast-client, a C++ client generator built on Boost.Beast with full OpenAPI 3.1 support, modern Boost/OpenSSL integration, and a working Petstore sample with CTest-backed imposter integration tests. Docs refreshed and the new generator is documented and linked.

New Features
- New cpp-boost-beast-client generator registered and documented (docs/generators.md, docs/generators/cpp-boost-beast-client.md); Petstore config added at bin/configs/cpp-boost-beast-client-petstore.yaml.
- OpenAPI 3.1: proper type detection (incl. null), free-form/any schemas via AnyType.h (boost::json::value), and composed schemas (allOf/oneOf).
- HTTP client abstraction (HttpClient/HttpClientImpl) with Accept/Content-Type negotiation and x-www-form-urlencoded. Petstore sample includes CMake/CTest, approval tests, and imposter-driven API tests.
Bug Fixes
- Correct path templating and query serialization (lists, collectionFormat: multi, explicit explode); fix response parsing (incl. arrays).
- Sanitize model names; fix map (de)serialization and include guards; correct enum metadata; reduce noisy core warnings; set webhook operationId and tag untagged webhooks as Webhooks.
- Safer default-response handling with compatibility checks in generated APIs.

^{Written for commit 2c2dac4. Summary will update on new commits.}

Fix maven pom

* Fixed names of the approval files for ApiTests. * Silence warnings due to boost/property_tree/json_parser.hpp * ApprovalTests only works when not using header-only boost::test * More clean shutdown of imposter when test(s) fail * Update petstore-config.yaml test config to add explicit values for all tested enpoints, rather than relying on imposter-provided default values. As of v4.5.2, imposter's defaults have changed. * Fixed CppBoostBeastClientCodegen compilation error triggered by refactoring of getAdditionalProperties(Schema) -> ModelUtils.

…enSSL - Remove boost_system COMPONENT from find_package (header-only in Boost 1.73+) - Add find_package(OpenSSL REQUIRED) and use OpenSSL::SSL OpenSSL::Crypto - Fix C++11 narrowing warnings in test files with static_cast - Update approval test files to match new JSON formatting from modern Boost

- Handle JsonSchema type without casting to ArraySchema - Use p.getItems() directly instead of casting to ArraySchema - Support OpenAPI 3.1 type arrays (e.g., type: ["string", "null"]) - Gracefully handle complex composed schemas with JsonSchema - Fix ClassCastException when processing OpenAPI 3.1 specs The generator now successfully processes OpenAPI 3.1 specifications with full JSON Schema 2020-12 compatibility.

- Remove unsafe instanceof JsonSchema checks that bypassed proper type handling - Use ModelUtils.getType() which properly handles OpenAPI 3.1 types array - Use p.getItems() instead of casting to ArraySchema - Add support for OpenAPI 3.1 null type - Leverage existing ModelUtils infrastructure for spec-version-agnostic processing This follows the same pattern used in DefaultCodegen.getSchemaType() and ModelUtils.getType() which check schema.getTypes() for JsonSchema (OAS 3.1) and schema.getType() for regular Schema (OAS 3.0). Fixes ClassCastException when processing OpenAPI 3.1 specs with type arrays (e.g., type: ["string", "null"]) and complex composed schemas.

- Map 'object' type to boost::property_tree::ptree (not custom AnyType class) - Follows pattern from cpp-pistache-server (nlohmann::json) and cpp-restsdk (json::value) - ptree is already used in AnyType.h for JSON serialization - Eliminates need for missing Object.h and AnyType.h files - Properly handles OpenAPI 3.1 JsonSchema free-form objects This is the correct approach for C++ Boost.Beast as ptree can hold any JSON value (string, number, object, array, null) and is already part of the codebase.

- Use hardcoded BOOST_BEAST_OPENAPI_CLIENT_ANYTYPE_H guard - Use nested namespace to match other generated files - Fixes include guard with dots issue

…ionIds, and non-JSON responses - DefaultCodegen: Populate _enum, isEnum, isInnerEnum for referenced enum schemas so enumName is computed, fixing 'Could not compute datatypeWithEnum' warnings for array items referencing enum schemas (e.g. TranscriptionInclude) - DefaultCodegen: Replace spurious 'Could not compute datatypeWithEnum' warning with silent fallback for non-enum array items and enum items without enumName - DefaultGenerator: Set operationId from webhook key for webhook operations missing operationId, fixing 'Empty operationId found for path' warnings - DefaultGenerator: Tag untagged webhook operations with 'Webhooks' instead of 'default', fixing 'Duplicate file path detected' collision with DefaultApi - ExamplesUtils: Downgrade 'No application/json content media type' from warn to debug for valid non-JSON responses (e.g. audio/octet-stream)

cubic-dev-ai

All reported issues were addressed across 93 files

_{Reply with feedback, questions, or to request a fix.

Re-trigger cubic}

bold84 · 2026-07-17T18:29:56Z

Addressed all 21 Cubic review findings in bfd48fb9545.

Highlights:

added verified HTTPS transport with SNI, hostname/certificate validation, TLS 1.2+, bounded resolve/connect/handshake/write/read/shutdown operations, and portable OpenSSL/Threads CMake targets
fixed request/response conversion for free-form, map, nested container, primitive, raw, multipart, and default-response cases
fixed allOf parent inheritance/JSON forwarding, null container preservation, query/header wire names and encoding, sample approvals, CMake paths, and Imposter startup bounds
added generator regression specs plus executable TLS, timeout, multipart, query, and header behavior tests

Verification:

focused generator tests: 3 passed
CLI package and canonical Petstore regeneration: passed
fresh CMake build with -DCMAKE_EXPORT_COMPILE_COMMANDS=1 -DCMAKE_CXX_FLAGS=-Werror: passed
generated Petstore tests: 40 API and 42 model cases passed

openai-cpp-sdk/ remains a local-only generation workspace and was not included.

cubic-dev-ai

All reported issues were addressed across 96 files

_{Tip: cubic used a learning from your PR history. Let your coding agent read cubic learnings directly with the cubic MCP.

Re-trigger cubic}

cubic-dev-ai

No issues found across 96 files

_{Re-trigger cubic}

bold84 · 2026-07-18T02:27:22Z

Addressed the 20 follow-up review findings in fee75e8c8b2 and resolved the corresponding threads.

Highlights:

corrected query/path/header serialization, optional query omission, XML fail-closed handling, response ranges/defaults, and extracted the shared operation partial
serialized shared-client execution, skipped SNI for IP literals, bracketed IPv6 Host values, and added configurable HTTP/HTTPS body limits
added requiredness-aware model presence, setter-based enum validation, assignment-safe typed enum tables, package-specific CMake targets, and installed public headers
made Imposter cleanup graceful and removed the post-readiness delay

Verification:

focused Maven generator tests: 4 passed
CLI reactor package: passed
generated API/model regression builds with -Werror: passed
dual generated-client CMake build: passed
regenerated Petstore build with -Werror: passed
Petstore CTest: 45 API + 45 model cases passed
install-tree downstream header compile: passed
independent final review: PASS

cubic-dev-ai

All reported issues were addressed across 53 files (changes from recent commits).

_{Reply with feedback, questions, or to request a fix.

Re-trigger cubic}

bold84 · 2026-07-18T02:48:21Z

Addressed the three latest review findings in 6928015244f and resolved their threads.

replaced positional boost::format path substitution with named placeholder replacement, preserving parameter associations regardless of declaration order
preserved literal percent-encoded path segments such as %20
honored the default explode: true for explicit style: form query arrays while retaining OpenAPI 2 CSV and multi behavior

Verification: focused generator tests passed; CLI package passed; focused generated client and regenerated Petstore built with -Werror; Petstore CTest passed 45 API + 45 model cases; sequential independent review passed.

cubic-dev-ai

All reported issues were addressed across 9 files (changes from recent commits).

_{Tip: Review your code locally with the cubic CLI to iterate faster.

Re-trigger cubic}

bold84 · 2026-07-18T03:15:44Z

Addressed the latest query serialization finding in aadb82ee4d0 and resolved the thread. Style-less query arrays now treat explicit explode: true as form-style repeated keys. The regression matrix covers omitted/omitted, omitted/true, omitted/false, explicit form/omitted, and explicit form/false, while existing OpenAPI 2 CSV/multi coverage remains green.

Verification: focused generator tests passed; generated regression client built with -Werror; CLI package passed; canonical regeneration produced no sample drift; sequential independent review passed.

bold84 · 2026-07-18T04:42:36Z

Completed the complex OpenAPI schema follow-up in e16269b2e2e.

fixed shared-pointer defaults for referenced enums
added recursive enum validation for arrays, maps, and nested containers
added OpenAPI form/deepObject query-map serialization
added focused OAS 3.0/3.1 regression coverage

Verification:

focused generator tests: 4 passed
generated OpenAI C++ SDK built completely with -Werror using 12 parallel jobs
git diff --check: passed
CircleCI: all 4 nodes passed
Cubic incremental review: 0 issues found across 8 files; no unresolved threads

openai-cpp-sdk/ and temporary generated output remain local-only and were not committed.

wing328 · 2026-07-18T16:14:35Z

Thanks for the contribution.

Let's give it a try and see if there is any feedback from our users.

LukasWoodtli and others added 30 commits March 25, 2025 20:37

Add generator for boost beast client

2140e91

Fix maven pom

Improve cpp-boost-beast client

eafb0ad

Add tests for exception propagation

700a72b

Add media types (Content-Type and Accept) and x-www-form-urlencoded

02b5c8b

Clean up and simplify

965c804

Fix query params and array responses

cfeab30

Add another test for query param with list

a874082

Simplify code and cleanup

c44059e

Add more tests for Pet API

ca3b929

Add store API tests and some improvements

5a40bc0

Add more tests for user API

f39fb2e

Run imposter for API tests from CMake (CTest)

b11537d

Add boost beast client tests to Maven project

f58001f

Add imposter to travis ci

3b15b77

Sanitize model names

234639a

Add generated Markdown file with docs

6e97713

Fix problems after rebase with upstream master

42b5f8a

Fix logger

675c9f7

Commit changes in generated files

f2b6924

Update generated doc

805d4b3

Decrease required CMake version for cpp-boost-beast-client example

1a49320

Fix parsing of response

8cacfdf

Partial fix for boost versions bigger than 1.71

ca89a97

Updated generated files per PR instructions

8031dd2

Merge master into cpp-boost-beast-fixes

13b8061

bold84 added 4 commits March 26, 2026 17:26

fix: Fix AnyType.h template with proper include guard and namespace

a02cee1

- Use hardcoded BOOST_BEAST_OPENAPI_CLIENT_ANYTYPE_H guard - Use nested namespace to match other generated files - Fixes include guard with dots issue

Merge remote-tracking branch 'origin/master' into cpp-boost-beast-fixes

7fc17a9

fix: repair C++ Boost Beast generation

7fed821

cubic-dev-ai Bot reviewed Jul 17, 2026

View reviewed changes

bold84 marked this pull request as draft July 17, 2026 13:35

fix(cpp-boost-beast): address review findings

bfd48fb

bold84 marked this pull request as ready for review July 18, 2026 00:18

cubic-dev-ai Bot reviewed Jul 18, 2026

View reviewed changes

bold84 marked this pull request as draft July 18, 2026 00:41

bold84 marked this pull request as ready for review July 18, 2026 00:45

cubic-dev-ai Bot reviewed Jul 18, 2026

View reviewed changes

fix(cpp-boost-beast): address follow-up review findings

fee75e8

cubic-dev-ai Bot reviewed Jul 18, 2026

View reviewed changes

fix(cpp-boost-beast): correct path and query serialization

6928015

cubic-dev-ai Bot reviewed Jul 18, 2026

View reviewed changes

Comment thread ...i-generator/src/main/java/org/openapitools/codegen/languages/CppBoostBeastClientCodegen.java Outdated

fix(cpp-boost-beast): honor explicit query explode

aadb82e

fix(cpp-boost-beast): support complex OpenAPI schemas

e16269b

wing328 added Client: C++ Enhancement: New generator labels Jul 18, 2026

wing328 added this to the 7.24.0 milestone Jul 18, 2026

wing328 added 2 commits July 18, 2026 22:30

update doc, samples

a23bb75

update doc

2c2dac4

wing328 merged commit b8f10df into OpenAPITools:master Jul 18, 2026
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C++ Boost.Beast Client Code Generator (with OpenAPI 3.1 support)

Credits

What this PR adds on top of #20971

Motivation

Build and test

PR checklist

Summary by cubic

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bold84 commented Jul 18, 2026

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