如何将文档从react native DocumentPicker response以byte[]的形式发送到web api

    DocumentPicker.show({
      filetype: [DocumentPickerUtil.images()],
    },(error,res) => {
 
  
        const data = new FormData();
        data.append('name', 'testName'); // you can append anyone.
        data.append('photo', {
          uri: res.uri,
          type: res.type,
          name: res.fileName,
        });

        fetch('http://ApiUrl/api/Controller/UploadFile', {
          method: 'post',
          headers: {
            'Content-Type': 'multipart/form-data',
          },
          body: data
        }).then(res => {
          console.log(res)
        })
        .catch(function(error) {
          console.log('There has been a problem with your fetch operation: ' + error.message);
            throw error;
          });
});