[Andrea Peruffo (andreaTP)]

Closes #55.

• Abstractions: MultipartBody, and byte array read and write on parse nodes and writers. Setting a multipart body on a request adds the boundary to the content type.
• JSON: byte arrays as base64.
• microsoft_kiota_serialization_multipart: the multipart/form-data writer, ported from kiota-python with its tests.

Beyond Python: as in .NET, each body gets its own boundary, an empty part is allowed, and a stream part is read from the start each time. Quotes and line breaks in part names and file names are escaped, as browsers do.

Checked with a client generated from a small description: a JSON part and a file part reach a local server byte for byte. Also adds the gem to CI, the release workflow, release-please and dependabot. The generator registers it in a Kiota PR after the release.

Before the release: please add a pending trusted publisher on RubyGems for microsoft_kiota_serialization_multipart, or its publish job fails.

[Copilot]

🟡 Changes recommended

Existing Content-Type headers can omit the boundary, and part content types permit MIME header injection.

2 open findings

• Reject CR/LF in part content_type to prevent header injection · New
• Override Content-Type to include the multipart boundary · New

What changed in this PR

Adds multipart/form-data serialization and byte-array support across the Ruby abstractions and JSON serializer.

Changes:

• Adds MultipartBody and a multipart serialization gem.
• Adds Base64 JSON byte-array serialization.
• Integrates multipart packaging, testing, dependency updates, and releases.

File	Description
release-please-config.json	Adds multipart version tracking.
README.md	Documents the multipart gem and test task.
Rakefile	Registers the multipart component.
Gemfile	Adds the local multipart gem.
components/​serialization/​multipart/​spec/​spec_helper.rb	Configures multipart specs.
components/​serialization/​multipart/​spec/​multipart_serialization_writer_spec.rb	Tests multipart serialization.
components/​serialization/​multipart/​spec/​multipart_serialization_writer_factory_spec.rb	Tests writer factory behavior.
components/​serialization/​multipart/​spec/​multipart_request_body_spec.rb	Tests request-body integration.
components/​serialization/​multipart/​spec/​files/​test_entity.rb	Provides a multipart test model.
components/​serialization/​multipart/​Rakefile	Defines component test and build tasks.
components/​serialization/​multipart/​microsoft_kiota_serialization_multipart.gemspec	Defines the new gem.
components/​serialization/​multipart/​lib/​microsoft_kiota_serialization_multipart/​version.rb	Defines the gem version.
components/​serialization/​multipart/​lib/​microsoft_kiota_serialization_multipart/​multipart_serialization_writer.rb	Implements multipart output.
components/​serialization/​multipart/​lib/​microsoft_kiota_serialization_multipart/​multipart_serialization_writer_factory.rb	Creates multipart writers.
components/​serialization/​multipart/​lib/​microsoft_kiota_serialization_multipart.rb	Exposes multipart library classes.
components/​serialization/​multipart/​Gemfile	Defines component dependencies.
components/​serialization/​json/​spec/​json_byte_array_spec.rb	Tests JSON byte arrays.
components/​serialization/​json/​lib/​microsoft_kiota_serialization_json/​json_serialization_writer.rb	Writes Base64 byte arrays.
components/​serialization/​json/​lib/​microsoft_kiota_serialization_json/​json_parse_node.rb	Decodes Base64 byte arrays.
components/​abstractions/​spec/​request_information_spec.rb	Tests multipart request headers.
components/​abstractions/​spec/​multipart_body_spec.rb	Tests multipart body behavior.
components/​abstractions/​lib/​microsoft_kiota_abstractions/​serialization/​serialization_writer.rb	Adds byte-array writer API.
components/​abstractions/​lib/​microsoft_kiota_abstractions/​serialization/​parse_node.rb	Adds byte-array parser API.
components/​abstractions/​lib/​microsoft_kiota_abstractions/​request_information.rb	Attaches multipart boundaries.
components/​abstractions/​lib/​microsoft_kiota_abstractions/​multipart_body.rb	Models and serializes multipart parts.
components/​abstractions/​lib/​microsoft_kiota_abstractions.rb	Exports MultipartBody.
.github/​workflows/​ruby.yml	Adds multipart CI coverage.
.github/​workflows/​release.yml	Publishes the multipart gem.
.github/​dependabot.yml	Enables multipart dependency updates.

🧠 Review effort: Balanced

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[Copilot]

🟡 Changes recommended

Multipart request handling can fail with direct subpath loading and can emit conflicting boundary parameters.

1 open finding

• Missing direct require causes MultipartBody NameError · New

2 resolved since last review

• Reject CR/LF in part content_type to prevent header injection
• Override Content-Type to include the multipart boundary

🧠 Review effort: Balanced

[Copilot]

🟡 Changes recommended

Existing boundary parameters and non-seekable serialized part streams can currently produce invalid requests or serialization failures.

1 open finding

• Replace existing boundary parameter before appending a new one · New

1 resolved since last review

• Missing direct require causes MultipartBody NameError

Previously missed (1)

In code that hasn't changed since last review

Use rewind helper for non-seekable model part streams

components/​abstractions/​lib/​microsoft_kiota_abstractions/​multipart_body.rb:112

This direct rewind makes model parts fail when a serialization writer returns a readable but non-seekable stream such as a pipe: such streams respond to rewind but raise Errno::ESPIPE. The class already handles that case for stream-valued parts via its rewind helper, so use the same helper here before reading.

🧠 Review effort: Balanced

[Copilot]

🟢 Approval recommended

The implementation, integration, and automated coverage consistently satisfy the described multipart and byte-array requirements.

0 open findings

1 resolved since last review

• Replace existing boundary parameter before appending a new one

🧠 Review effort: Balanced

[Vincent Biret (baywet)]

Thanks for the contribution!

[github-actions]

This pull request has conflicting changes, the author must resolve the conflicts before this pull request can be merged.

[github-actions]

Conflicts have been resolved. A maintainer will take a look shortly.

[Copilot]

🟡 Changes recommended

The Dependabot configuration contains duplicate directory keys and must use a separate update entry.

1 open finding

• Duplicate YAML key overwrites serialization update configuration · New

🧠 Review effort: Balanced

[Copilot]

🔵 Needs a closer look

Boundary parameters containing valid whitespace around the equals sign are duplicated instead of replaced.

0 open findings

1 resolved since last review

• Duplicate YAML key overwrites serialization update configuration

🧠 Review effort: Balanced

[github-actions]

Conflicts have been resolved. A maintainer will take a look shortly.

[Copilot]

🟡 Changes recommended

Premature backing-store completion can silently omit model fields in repeated parts or retries after serialization failures.

1 open finding

• Defer model cleanup until multipart serialization completes · New

1 resolved since last review

• Stream multipart uploads without buffering entire files

🧠 Review effort: Balanced

[Vincent Biret (baywet)]

Thank you for making the changes!

[Andrea Peruffo (andreaTP)]

Vincent Biret (@baywet) ready to merge whenever you can, then #180 can ship 0.25.0.

[Copilot]

🟢 Approval recommended

No blocking issues remain, and regression coverage addresses multipart encoding, boundaries, and backing-store failure handling.

No open issues 🎉

1 resolved since last review

• Defer model cleanup until multipart serialization completes

_{Review effort: Balanced}