Flutter how to send multiple files to http post - dart

Question

I'd like to send two files to http post
curl looks like this
curl -X POST "https://api-us.faceplusplus.com/facepp/v3/compare" \
-F "api_key=<api_key>" \
-F "api_secret=<api_secret>" \
-F "image_file1 =file1" \
-F "image_file1 =file2"
I tried like this.
File first;
File second;
var uri = Uri.parse('https://api-us.faceplusplus.com/facepp/v3/compare');
var request = new http.MultipartRequest("POST", uri);
request.fields['api_key'] = apiKey;
request.fields['api_secret'] = apiSecret;
request.files.add(await http.MultipartFile.fromPath('image_file1', first.path, contentType: new MediaType('application', 'x-tar')));
request.files.add(await http.MultipartFile.fromPath('image_file2', second.path, contentType: new MediaType('application', 'x-tar')));
var response = await request.send();
print(response);
But it returns this
NoSuchMethodError: Class 'String' has no instance getter 'path'.
How can I send these properly?

Answer 1

It doesn't look like first and second are actually Files. When they are definitely files, as in the following example, I get 401 (as expected, as I have a dummy api key).
main() async {
File first = File('pubspec.yaml');
File second = File('analysis_options.yaml');
Uri uri = Uri.parse('https://api-us.faceplusplus.com/facepp/v3/compare');
http.MultipartRequest request = new http.MultipartRequest('POST', uri);
request.fields['api_key'] = 'apiKey';
request.fields['api_secret'] = 'apiSecret';
request.files.add(await http.MultipartFile.fromPath('image_file1', first.path,
contentType: new MediaType('application', 'x-tar')));
request.files.add(await http.MultipartFile.fromPath(
'image_file2', second.path,
contentType: new MediaType('application', 'x-tar')));
http.StreamedResponse response = await request.send();
print(response.statusCode);
}

Answer 2

import 'dart:io';
import 'package:http/http.dart' as http;
import 'package:path/path.dart';
class Post {
String title = '';
String description = '';
List<File> files = [];
Future<http.StreamedResponse> sendFiles() async {
try {
var uri = Uri.parse('https://example.com/api-endpoint');
var request = http.MultipartRequest('POST', uri);
// Headers
request.headers.addAll({
'Accept': 'application/json',
'Authorization': 'Bearer $token',
});
// Fields
request.fields['title'] = title;
request.fields['description'] = description;
// Files
await Future.forEach(
files,
(file) async => {
request.files.add(
http.MultipartFile(
'files',
(http.ByteStream(file.openRead())).cast(),
await file.length(),
filename: basename(file.path),
),
)
},
);
return await request.send();
} catch (err) {
print(err);
return null;
}
}
}

Answer 3

You can try with Flutter DIO Package
https://pub.dev/packages/dio
import 'package:dio/dio.dart';
// Create a Dio instance
final Dio dio = Dio();
// Set up the request options
Options options = Options(
method: 'POST',
);
// Create a FormData instance to hold the files you want to upload
FormData formData = FormData();
// Add the files to the FormData instance
formData.files.addAll([
MapEntry('file1', await MultipartFile.fromFile(file1Path)),
MapEntry('file2', await MultipartFile.fromFile(file2Path)),
// Add more files here if you want
]);
try {
// Send the POST request
Response response = await dio.post(
url,
data: formData,
options: options,
);
// Do something with the response
print(response.data);
} catch (e) {
// show my error
log(e);
}