Flutter - how to download excel file from a post http response

Question

I'm new to flutter programming and i need to be able to download an excel file from http post request. I have two issues:

• The response in flutter is null whereas in postman it displays something. The details below

[Postman response]

The Content-type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet

• I dont know how to process that response to actually get the file downloaded in the location specified by the user

Can someone help me please

This is what i have soo far

Dio? http;

BaseOptions options = new BaseOptions(
      baseUrl: "****/",
      headers: {
        'Accept': 'application/json',
        'Content-type': 'application/json'
      },
      responseType: ResponseType.json,
    );

http = new Dio(options);

static Future<dynamic> getClientsFile(String sheetName) async {
    Directory dir = await getApplicationDocumentsDirectory();
    String fileLocation = dir.path + "/" + sheetName + ".xlsx";

    return http!
        .download(
          "clients/exports",
          fileLocation,
          data: {"sheetName": sheetName, "type": "xlsx"},
          options: Options(method: "POST", responseType: ResponseType.bytes),
        )
        .then((value) => print(value));
  }

await ClientController.getClientsFile(sheetName);