How to Http Post with Json Body on Flutter - dart

Question

I am trying to get data from API. I need to pass value from the body, in postman without a header: application/JSON data is not displayed.
final response = await http.post(
"http://192.168.10.25:8080/Login/validateusername",
body: {"username": "user#PYA"},
headers: {'Content-Type': 'application/json'},
);
Error Message:
E/flutter (28851): [ERROR:flutter/shell/common/shell.cc(184)] Dart Error: Unhandled exception:
E/flutter (28851): Bad state: Cannot set the body fields of a Request with content-type "application/json".

Answer 1

Add the content type application/json
Future<String> apiRequest(String url, Map jsonMap) async {
HttpClient httpClient = new HttpClient();
HttpClientRequest request = await httpClient.postUrl(Uri.parse(url));
request.headers.set('content-type', 'application/json');
request.add(utf8.encode(json.encode(jsonMap)));
HttpClientResponse response = await request.close();
// todo - you should check the response.statusCode
String reply = await response.transform(utf8.decoder).join();
httpClient.close();
return reply;
}

Answer 2

Simply encode body to json object when using content-type "application/json"
http.Response response = await http.post( uri , headers: headers, body: JsonEncoder().convert(body));

Answer 3

Another simple way is as bellow
import 'package:http/http.dart' as http;
String body = json.encode({
'foo': 'bar',
'complex_foo' : {
'name' : 'test'
}
});
http.Response response = await http.post(
url: 'https://example.com',
headers: {"Content-Type": "application/json"},
body: body,
);

Answer 4

use the http dart package
var data = {username:"username",password:"password"};
http.Response response = await http.post(
"yourApiroute",
headers: {'Content-Type': 'application/x-www-form-urlencoded'},
body: {"username": data.phone, "password": data.password});

Answer 5

var json = jsonCodec.encode(data);
print("json=$json");
var url = "http:yourAPIrouter.com/etc";
var response = await http.post(
url,
headers:{ "Accept": "application/json" } ,
body: { "json": '$json'},
encoding: Encoding.getByName("utf-8")
);
and dont forget add the key "json" in postman

Answer 6

I am doing almost the same. However, I tried to avoid doing back-end, like in your case. I just did a minimal php request so that I would not waste or patience learning what is needed to develop a user management controller.
However, I faced several limitations and problems that Flutter alone can't solve. After some denial, I gave a try. Lumen, a light version of the Laravel Framework, some tutorials and some past experience, I eventually realized that the API should carry most of the authentication, and not the application itself. I digressed.
In my case, the code of the fuction to a http post is:
Future<Post> createPost() async {
final url = "http://localhost:8000/api/login";
Map<String, String> body = {
'user': user.text,
'pass': pass.text,
};
await http.post(url, body: body);
print(body);
return http.;
}
I first convert it into a map. I prefer this method over parsing json, because down the line, if I need to add more variables, I just make the map bigger.
I just have a question: What does your http://192.168.10.25:8080/Login/validateusername look like? I think that there is no need to specify the type of information that your body parses.