Dart: Get POST parameters on server side - dart

Question

I send some data from client side using POST request
var value = new Map<String, String>();
value["param1"] = 'value1';
value["param2"] = 'value2';
value["param3"] = 'value3';
HttpRequest.postFormData('http://localhost:8080/', value);
and try to get this data on the server side:
HttpServer.bind(InternetAddress.ANY_IP_V6, 8080).then((server) {
server.listen((HttpRequest request) {
//TODO: process POST request
});
});
But how can I get POST values from the request as Map< string, string>?
upd 1
But as I see result of
var jsonString = await request.transform(UTF8.decoder).join();
depends on type of post message. If I change it result will be
multipart/form-data
------WebKitFormBoundaryoQQD7N0iA5zS8qmg
Content-Disposition: form-data; name="param1"
value 1
------WebKitFormBoundaryoQQD7N0iA5zS8qmg
Content-Disposition: form-data; name="param2"
value 2
------WebKitFormBoundaryoQQD7N0iA5zS8qmg
Content-Disposition: form-data; name="param3"
value 3
------WebKitFormBoundaryoQQD7N0iA5zS8qmg--
text/plain
param1=value 1
param2=value 2
param3=value 3
application/x-www-form-urlencoded
param1=value+1&param2=value+2&param3=value+3
As I have already asked how can I convert it to Map< string, string>?

Answer 1

Here is a complete tutorial https://www.dartlang.org/docs/tutorials/httpserver/#handling-post
String jsonString = await request.transform(UTF8.decoder).join();
or
Map result = await request.transform(UTF8.decoder).join().then(JSON.decode);

Answer 2

I have the same question, and I didn't find any solution until now. I need to pass a map from client to server, and server to use that map to interrogate a mongodb database. Client send that map, but server receive a string. Any conversion to json return also string, not a map.
On the client side I send a map named query:
await HttpRequest.postFormData('http://localhost:8085/$_coll',query).then((HttpRequest response)
On the server side :
if (request.method == 'POST') {
query = await request.transform(utf8.decoder).join();
}
I've tried to encode/decode to json, but with no success.