title: How to send FormData with Dio?
body: <p>Hello I am sending a FormData using Dio but when this is sent, the website returns an error</p>
  <pre><code>    var formData = FormData.fromMap({
        &quot;ctl00\$ScriptManager1&quot;: &quot;ctl00\$UpdatePanel1&quot;,
        &quot;__EVENTTARGET&quot; :&quot;ctl00\$cphPage\$productsControl&quot;,
        &quot;__EVENTARGUMENT&quot; : &quot;&quot;,
        &quot;__LASTFOCUS&quot; : &quot;&quot;,
        &quot;PageLoadedHiddenTxtBox&quot; : &quot;Set&quot;,
        &quot;Language&quot; : &quot;es-MX&quot;,
        &quot;CurrentLanguage&quot; : &quot;es-MX&quot;,
        &quot;Currency&quot; : &quot;&quot;,
        &quot;__VIEWSTATE&quot; :&quot;/sadasd.....&quot;,
        &quot;__VIEWSTATEGENERATOR&quot; : &quot;C0E71A90&quot;,
        &quot;ctl00\$txtSearch&quot; : &quot;&quot;,
        &quot;ctl00\$cphPage\$productsControl\$TopTools\$cbxSortType&quot; : &quot;&quot;,
        &quot;ctl00\$cphPage\$productsControl\$TopTools\$cbxPageSize&quot; : &quot;-1&quot;,
        &quot;ctl00\$taxes\$listCountries&quot; : &quot;54&quot;,
        &quot;__ASYNCPOST&quot; : &quot;true&quot;,
        &quot; &quot; : &quot;&quot;
      });
  var dio = Dio();
      dio.interceptors.add(InterceptorsWrapper(onRequest: (RequestOptions options) async {
        var customHeaders = {
          'content-type': 'text/html; charset=utf-8',
          'application':'x-www-form-urlencoded',
          'Cookie': 'uid=rBQBc2CisZdxWU5XBBmMAg==; ASP.NET_SessionId=tedc4xrih1hk1ykbdzlakuvb; ASPNET_Session=client=BLUR; ShopMSAuth=0102A9A3B88FC919D908FEA90B7DF1D119D908000442004C005500520000012F00FF'
          // other headers
        };
        options.headers.addAll(customHeaders);
  
        return options;
      }));
      Response response = await dio.post(url, data: formData, options: Options(
          contentType: 'text/html; charset=utf-8',
          followRedirects: true
      ));
  
      print(response.data);
  </code></pre>
  <p>When I check the requests by the browser, the requests at the end have as parameters:</p>
  <pre><code>__ASYNCPOST :true
   :&quot;&quot;
  </code></pre>
  <p>Will the form be fine like this?</p>