React Native上传音频至NestJS仅传元数据，文件内容为空Buffer

我使用 React Native 客户端和 NestJS 服务端开发录制音频并上传的功能，该 API 端点在 Postman 和 React 网页端测试均正常，但通过 React Native 上传文件时，服务端仅能收到文件元数据，文件内容为 size 为 0 的空 Buffer。在 stopRecording 处理函数中，已确认发送请求前 formData 确实包含音频文件内容。

React Native 组件代码 #

const AudioInput3 = () => {
  const [recording, setRecording] = useState<Recording | null>(null);
  const [recordingStatus, setRecordingStatus] = useState("idle");
  const [audioPermission, setAudioPermission] = useState(false);

  const startRecording = async () => {
    try {
      if (audioPermission) {
        await Audio.setAudioModeAsync({
          allowsRecordingIOS: true,
          playsInSilentModeIOS: true,
        });
      }

      const newRecording = new Audio.Recording();
      await newRecording.prepareToRecordAsync(
        Audio.RecordingOptionsPresets.HIGH
      );
      await newRecording.startAsync();

      setRecording(newRecording);
      setRecordingStatus("recording");
    } catch (err) {
      console.error("Failed to start recording", err);
    }
  };


  async function stopRecording() {
    try {
      if (!recording) return;
      if (recordingStatus === "recording") {
        await recording.stopAndUnloadAsync();
        const recordingUri = recording.getURI() as string;

        const filename = `recording_${Date.now()}.caf`;

        const filePath = FileSystem.documentDirectory + "recordings/";

        setRecording(null);
        setRecordingStatus("stopped");

        const fileData = await FileSystem.readAsStringAsync(recordingUri, {
          encoding: FileSystem.EncodingType.Base64,
        });

        const blob = new Blob([fileData], { type: "audio/x-caf" });
        const file = new File([blob], filename, {
          type: "audio/x-caf",
        });

        const fileSize = file.size;
        const formData = new FormData();
        formData.append("file", file);
        const response = await fetch(urlResolver.uploadToStorage(), {
          method: "POST",
          body: formData,
          headers: {
            "Content-Type": "multipart/form-data",
            "Content-Length": String(fileSize),
          },
        });
      }
    } catch (error) {
      console.error(error);
    }
  }
}

已尝试的解决方案 #

• 移除请求头，无效；
• 用 axios 替换 fetch，无效；
• 关闭 react-native-debugger，无效。

NestJS API 端点代码 #

@Post("upload")
@UseInterceptors(FileInterceptor("file"))
uploadFile(@UploadedFile() file: Express.Multer.File) {
  console.log(file); 
}

服务端返回结果（空 Buffer） #

{
  fieldname: 'file',
  originalname: 'recording_1683615927273.caf',
  encoding: '7bit',
  mimetype: 'audio/x-caf',
  buffer: <Buffer >,
  size: 0
}

内容的提问来源于stack exchange，提问作者Kittichote Chain