fix: missing context (set) in mapResponse for ElysiaFile

[Rouret]

Fix #1427

Context

In mapResponse, the ElysiaFile case was calling handleFile without passing the current context (set).
Because of that, the response had no access to the headers defined by middleware/plugins, making it impossible for the CORS plugin to apply its headers.

Fix

Pass the current set object into handleFile in the ElysiaFile case so that headers (including CORS) are applied correctly.

Test

I didn’t write tests because this fix is very small and only restores the expected behavior (passing the current context to handleFile)

Enregistrement.de.l.ecran.2025-09-23.a.19.03.52.mov

Summary by CodeRabbit

• Bug Fixes

  • File responses now correctly apply response headers and status codes, improving compatibility with downloads and streamed files (e.g., proper Content-Type/Disposition).
  • Resolves cases where file responses could miss expected headers, leading to inconsistent client behavior.

• Refactor

  • Internal handling of file responses streamlined to ensure consistent propagation of response metadata, enhancing reliability without changing user-facing APIs.

[coderabbitai]

Walkthrough

Updated Bun adapter’s mapResponse to pass the response “set” object into handleFile when handling ElysiaFile, aligning with a revised handleFile signature that now accepts (File, set).

Changes

Cohort / File(s)	Summary
Bun adapter: ElysiaFile mapping src/adapter/bun/handler.ts	In mapResponse, ElysiaFile branch now calls handleFile(value, set) instead of handleFile(value), propagating headers/status via set.

Sequence Diagram(s)

sequenceDiagram
  autonumber
  actor Client
  participant Server as Elysia (Bun adapter)
  participant Mapper as mapResponse
  participant FileUtil as handleFile
  participant Bun as Bun Response

  Client->>Server: HTTP Request
  Server->>Mapper: mapResponse(response, set)
  alt response is ElysiaFile
    Mapper->>FileUtil: handleFile(File, set)  <!-- pass-through of set -->
    Note right of FileUtil: Apply headers/status (e.g., CORS) via set
    FileUtil-->>Mapper: File-based Response
  else other response types
    Mapper-->>Server: Mapped Response
  end
  Mapper-->>Server: Final Response
  Server-->>Bun: send Response
  Bun-->>Client: HTTP Response (headers applied)

Loading

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

I hop through headers, nimble and spry,
Passing the set as responses fly.
Files now wear CORS like a proper coat,
So browsers cheer with every note.
Tiny tweak, tidy trail—
Thump-thump! Bugs derail. 🐇✨

Pre-merge checks and finishing touches

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title Check	✅ Passed	The title concisely and accurately describes the primary change — adding the missing "set" context in mapResponse for ElysiaFile so handleFile receives it; it is specific, short, and directly related to the changeset.
Linked Issues Check	✅ Passed	The change passes the request context ("set") into handleFile for ElysiaFile responses (src/adapter/bun/handler.ts), which directly addresses the linked issue [#1427] by allowing middleware and plugin headers, including CORS, to be applied to file responses as described in the issue.
Out of Scope Changes Check	✅ Passed	Based on the provided summary the changes are narrowly scoped to passing the "set" context into handleFile for the ElysiaFile branch of mapResponse and do not show unrelated file or behavioral changes, so no out-of-scope modifications are detected.
Docstring Coverage	✅ Passed	No functions found in the changes. Docstring coverage check skipped.

✨ Finishing touches

• 📝 Generate Docstrings

🧪 Generate unit tests

• Create PR with unit tests
• Post copyable unit tests in a comment

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📜 Recent review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between eb4d126 and ea8a116.

📒 Files selected for processing (1)

• src/adapter/bun/handler.ts (1 hunks)

🧰 Additional context used

🧬 Code graph analysis (1)

src/adapter/bun/handler.ts (2)

src/adapter/utils.ts (1)

• handleFile (7-63)

src/universal/file.ts (1)

• ElysiaFile (99-166)

🔇 Additional comments (1)

src/adapter/bun/handler.ts (1)

42-45: LGTM! This fix correctly addresses the CORS header issue.

The CORS plugin for Elysia adds support for customizing Cross-Origin Resource Sharing behavior, and this change ensures that CORS headers are properly applied to responses when serving files via ElysiaFile. The modification properly passes the set context to handleFile, allowing middleware-applied headers (including CORS) to be included in the response.

Looking at the handleFile implementation in the utils module, it correctly handles the optional set parameter and applies the headers when present.

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