如何从 dart/flutter 将 int/integer 值发布为 json

Question

I am using asp.net core web API as back-end. There is a method that accepts a single integer value.

Method([FromBody] int value)

I want to post the integer value from dart/flutter. I tried the following with the dart http package.

Http.post(url, body:0,headers:{"content-type":"application/json"}

Http.post(url, body:{0},headers:{"content-type":"application/json"}

Http.post(url, body:convert.jsonEncode(0),headers:{"content-type":"application/json"}

Http.post(url, body:convert.jsonEncode({0}),headers:{"content-type":"application/json"}

All my above tries failed with error "Invalid argument: invalid request body "0""

Answer 1

You can try this code.

Http.post(url, body:{"id": "0"},headers:{"content-type":"application/json"}

Answer 2

Please refer my code

1. import

   import 'package:http/http.dart' as http;

2. http request

   var client = new http.Client(); client.post(Uri.encodeFull("Your url"), body: { "param1": "value1", "param2": 11, // integer value type }).then((response) { client.close(); if (this.mounted && response.statusCode == 200) { //enter your code for change state } }).catchError((onError) { client.close(); print("Error: $onError"); });

I hope it will help you.

PS:

var client = new http.Client();
var response = await client.post(Uri.encodeFull("Your Url"), body : "0", header : {/*Your headers*/"});

Answer 3

Can you try bellow one

var queryParameters = {
                'value': '0'
        };
        var uri =
                Uri.https('www.myurl.com', '/api/sub_api_part/', queryParameters); //replace between  part and your url
        var response = await http.get(uri, headers: {
                    HttpHeaders.contentTypeHeader: 'application/json'
        });

Answer 4

I had the same problem when trying to send an HTTP request to an API that has an integer as one of its arguments(age). Dart wanted me to convert the int into a string and the API was not accepting the int as a string. Hence I was getting the same error and ended up in this question.

My solution was to store the input in a map, add a header {"content-type":"application/json"} and pass the map in the body arguement.

import 'dart:convert';
import 'package:http/http.dart' as http;


Future<String> register_user() async {
  var req_body = new Map();

  req_body['username'] = 'John Doe';
  req_body['age'] = 20; /* The integer */

  final response = await http.post(
        'http://127.0.0.1:8081/user/register',
         headers: {'Content-Type': 'application/json'},
         body: jsonEncode(req_body));


  if (response.statusCode == 200) {
    var object = json.decode(response.body);

    return object.toString();
  } else if (response.statusCode == 422) {
    return 'Error';
  } else {
    return 'Can not connect to server';
  }
}