fix(*): translate native compress failures to CompressError instead of null - #397
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Introduce an optional `code` field on `CompressError` so callers can branch on failure kind without string-matching the message. Stable values emitted by the native side: `unsupported_format`, `decode_failed`, `encode_failed`, `io_failed`, `unknown`. Unknown codes pass through verbatim for forward-compat. Additive change — `code` is nullable and the existing single-arg constructor is unchanged. Refs #252 Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
…f null
Native compress failures on Android/iOS/macOS previously reported back
to Dart as `reply(null)` / `result(nil)`, forcing callers to do a bare
null-check with no diagnostic — and creating a latent `TypeError` on
`compressWithList` (common), whose signature is non-nullable but which
happily returned the native null unchanged.
Native side (Android Kotlin / iOS Objective-C / macOS Swift):
- `reply(null)` / `result(nil)` on the failure path becomes
`replyError(code, msg)` / `result([FlutterError ...])` /
`FlutterError(code:..., message:...)` with a stable code:
`unsupported_format`, `decode_failed`, `encode_failed`, `io_failed`,
`unknown`.
- iOS `handleCompressFileToFile:` also translates `writeToURL:`
failure from a silent `result(nil)` to `io_failed` with the target
path in the message.
Dart side (common / macOS / ohos):
- Introduce a private `_invoke<T>` helper on each platform impl that
catches `PlatformException` and rethrows `CompressError(msg, code:
...)`. Every compress-related `_channel.invokeMethod` call now
goes through it.
- Delete three unreachable `if (!support) return null;` branches in
common — `FlutterImageCompressValidator.checkSupportPlatform`
already throws `UnsupportedError` when a format is not supported;
it never actually returns `false`.
- Add a defensive `if (result == null) throw CompressError(...)` in
`compressWithList` (common), aligning with the guard macOS and ohos
already had. This closes the latent `TypeError` — the native side
should no longer emit a `success(null)` on the failure path, but
the guard keeps the non-nullable return type honest.
- Replace `throw Exception('Compress failed')` in macOS and ohos
`compressWithList` with `throw CompressError('Compress failed')`
for consistency.
Existing null-checking callers still compile — public signatures
unchanged. Callers who already catch `CompressError` now get a real
error kind + message instead of an opaque null return.
Refs #252, refs #396
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Re-wrap CompressError.toString ternary to match `dart format` output. No behavior change. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
reply(null)/result(nil), forcing Dart callers to bare null-checks with no diagnostic — and creating a latentTypeErroroncompressWithList(common), whose signature is non-nullable but which returned the native null unchanged.unsupported_format,decode_failed,encode_failed,io_failed,unknown) viareplyError/FlutterError; Dart platform impls catchPlatformExceptionand rethrowCompressError(message, code: ...).CompressError(documented in the platform interface) now get a real error kind + message; callers doingresult == nullstill compile.if (!support) return null;branches in common (checkSupportPlatformalready throwsUnsupportedError), and adds a defensive null guard tocompressWithList(common) matching macOS/ohos.Related issues
CompressErrorto be exposed on the Flutter side. The class was already exported since 🎨 Add melos and support platform interface #242, but this PR addresses the underlying pain: native failures are now surfaced asCompressErrorinstead of silent nulls.compressWithFile/compressAndGetFile/compressAssetImagefromFuture<T?>toFuture<T>), which is a v-next candidate and deliberately out of scope here.Wire protocol
Failure codes emitted by the native side (documented on
CompressError.code):unsupported_formatCompressFormatdecode_failedencode_failedio_failedunknownmessagecarries the reason)Test plan
melos run analyzeclean across all 7 packagesmelos run verify_ios_behavior) — golden path unchanged, only failure paths touchedmelos run verify_macos_behavior)compressWithListon an Android device; before this change,BitmapFactory.decodeByteArrayreturning null caused a DartTypeError(non-nullableUint8List= null). After this change, callers receiveCompressError(code: 'unknown', message: '...').compressWithFilewith a non-image file — before:result == nullwith no info. After:CompressError(code: 'decode_failed', message: 'Input file is not a decodable image (mime=application/octet-stream, path=...)').Note: the repo has no
test/unit-test scaffolding today — behavioral coverage lives inpackages/flutter_image_compress/example/integration_test/compress_test.dart. Adding unit tests for the_invoketranslator would require setting upflutter_test+test/in three platform packages, which is a bigger separate change; happy to add it if reviewers prefer.🤖 Generated with Claude Code