如何使用 url 编码 header 和 Flutter/Dart 中的主体制作 HTTP POST 请求

Question

I've been trying to make a post request to an endpoint that requires both the request header and body to be encoded however so far the responses I've been getting back are 400 errors. The only way I've gotten the request to work so far is with a curl request and Thunder client in VSCode. Below is my request body. Any sort of help would be appreciated thanks.

With the flutter http package:

Response response = await post(
      Uri.parse(URL), 
      headers: {
      'Authorization': 'Basic ${base64Encode(utf8.encode('$ID:$SECRET'))}',
      'Content-Type': 'application/x-www-form-urlencoded',
      }, 
      encoding: Encoding.getByName('utf-8'),
      body: {
      'grant_type': 'refresh_token',
      'refresh_token': refreshToken,
      'redirect_uri':
          redirectUri,
      }
    );

Error:

With the flutter Dio package:

Dio.Dio dio = Dio.Dio();
    Dio.Response response = await dio.post(
        URL,
        data: {
          'grant_type': 'refresh_token',
          'refresh_token': refreshToken,
          'redirect_uri':
              redirectUri,
        },
        options:
            Dio.Options(contentType: Dio.Headers.formUrlEncodedContentType, headers: <String, String>{'Authorization': 'Basic ${base64Encode(utf8.encode('$ID:$SECRET'))}'}));

Error:

Answer 1

As your getting responce back from the server 400 so api is hitting server. Try debug from backend to know exact issuse in detail.