how to use flutter dio connect-type multipart? - flutter

Question

my code here
Dio dio = new Dio();
String fileName = event.file!.path.split('/').last;
FormData formData = FormData.fromMap({
"file":
await MultipartFile.fromFile(event.file!.path, filename: fileName),
});
try {
var response = await dio.post(
"url",
data: formData,
options: new Options(
contentType: "multipart/form-data",
headers: {
"token": await getToken(),
// "Content-Type": "multipart/form-data"
}),
// headers: {"token": "test:1234"}),
);
}
catch (e){
print(e);
}
my error version 1
error type. DioErrorType.other
error : SocketException : OS Error Connection refused,errorno=61
and
my error version 2
error type. DioErrorType.response
error : Http status error[400]
my requestOptions here
method = "POST"
_defaultContentType = "multipart/form-data"
How can I hand over the file to the server? The problem I think is that the content-type is not suitable, so there seems to be an error.

Answer 1

I have a similar implementation. I also use Dio, though in my code, I have it abstracted away with _api.
Future<Response> uploadLogo({#required File file}) async {
String fileName = file.path.split('/').last;
FormData formData = FormData.fromMap({"file": await MultipartFile.fromFile(file.path, filename:fileName) });
return await _api.post(url: url, data: formData);
}
Note that I don't even set the content type. I suspect that Dio looks at the type of object in the data parameter, and handles the appropriate headers/encoding under the hood.
Also, if you have having the content-type set to something unexpected, I'd recommend checking if you are using any RequestInterceptor's. I was, and had to write an exception, because I was setting it correctectly, by my RequestInterceptor was overriding it, (because all of my other endpoints wanted JSON):
class RequestInterceptor extends InterceptorsWrapper {
#override
void onRequest(RequestOptions options, handler) {
if(!options.headers.containsKey('content-type')) {
options.headers['content-type'] = 'application/json';
}
// ...
super.onRequest(options, handler);
}
}