Flutter: How to http POST image to Microsoft Cognitive Services - http

Question

I am trying to POST an image taken from the camera to Microsoft Cognitive Service's Face API (using the Face - Detect method). However, when I try it returns the 'Response 415':
{
"error": {
"code": "BadArgument",
"message": "Invalid Media Type."
}
}
Here is my code for this method:
final bytes = image.readAsBytesSync();
var uri = Uri.parse("https://australiaeast.api.cognitive.microsoft.com/face/v1.0/detect?returnFaceId=true&returnFaceLandmarks=false");
var request = new http.MultipartRequest("POST", uri);
var multipartFile = new http.MultipartFile.fromBytes('url', bytes, contentType: new MediaType('image', 'jpeg'));
request.headers['Ocp-Apim-Subscription-Key'] = "9c261636281d42c0947d89fe3982df73";
request.headers['Content-Type'] = "application/octet-stream";
request.files.add(multipartFile);
var response = await request.send();
print(request);
print(response.statusCode);
response.stream.transform(utf8.decoder).listen((value) {
print(value);
}
I used the Flutter Image Picker plugin to take the picture and get it to show up fine on the screen. All other operations I've tried with Microsoft Cognitive Services work fine - it is only uploading this image that is giving me problems.

Answer 1

I think you don't need a MultipartRequest but just a Request and assign the bodyBytes property:
final bytes = image.readAsBytesSync();
var uri = Uri.parse("https://australiaeast.api.cognitive.microsoft.com/face/v1.0/detect?returnFaceId=true&returnFaceLandmarks=false");
var request = new http.Request("POST", uri)
..headers['Ocp-Apim-Subscription-Key'] = "9c261636281d42c0947d89fe3982df73"
..headers['Content-Type'] = "application/octet-stream"
..bodyBytes = bytes;
var response = await request.send();
print(request);
print(response.statusCode);
response.stream.transform(utf8.decoder).listen((value) {
print(value);
});