问题

我已创建一个REST POST端点，在此端点中，我正在进行第三方API调用，并将从第三方API获得的响应作为REST端点的响应发送。

以下是代码部分，你提到的问题发生在return Response.ok(contents.toString())这一行，出现了JSON转换异常。

异常信息如下：

[SEVERE] aqueduct: POST /uploadurl 1047ms 500 {user-agent : Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.88 Safari/537.36\nconnection : keep-alive\
ncache-control : no-cache\npostman-token : 8ba3e1e9-38c7-37ac-da97-5bb3de983622\naccept-encoding : gzip, deflate, br\ncontent-type : application/json\nsec-fetch-site : cross-site\naccept : */*\nsec-fe
tch-mode : cors\naccept-language : en-US,en;q=0.9\norigin : chrome-extension://fhbjgbiflinjbdggehcddcbncdddomop\ncontent-length : 103\nhost : localhost:8888\n}  Converting object to an encodable objec
t failed: Instance of &#39;StringBuffer&#39; ...

以下是你想要发送作为响应的来自第三方API的数据：

{&quot;objectUrls&quot;:[{&quot;signedUrl&quot;:&quot;https://example.com&quot;,&quot;path&quot;:&quot;folder3/sub1/mysensordata.log&quot;}]}

请注意，异常信息中的"是HTML实体编码，实际上应该是双引号"。你需要在发送响应之前将HTML实体编码解码为JSON字符串。

如果你需要更多的帮助来解决这个问题，请提供更多关于代码中的JSON编码和发送响应的详细信息。

英文:

I have created a rest post endpoint, wherein I am making third party API call and the response that I am getting from third party API is being sent as a response from the rest endpoint

here is the code:

@override
  Controller get entryPoint {
    String dataRecieved;
    var completer = new Completer();
    var contents = new StringBuffer();
    final router = Router();

    // Prefer to use `link` instead of `linkFunction`.
    // See: https://aqueduct.io/docs/http/request_controller/
    router.route(&quot;/uploadurl&quot;).linkFunction((request) async {
      final req = await request.body.decode();
      var envalue = json.encode(req);
      print(envalue);
//      print( await request.body.decode());
      HttpClient client = new HttpClient();
      client.badCertificateCallback =
          ((X509Certificate cert, String host, int port) =&gt; true);
      var auth = &#39;Bearer &#39; +
          &#39;eyJ...&#39;;

      await client
          .postUrl(Uri.parse(
              &#39;https://&lt;removed&gt;/api/datalake/v3/generateDownloadObjectUrls&#39;))
          .then((HttpClientRequest requestSend) {
        requestSend.headers
            .add(&quot;Content-Type&quot;, &quot;application/json; charset=UTF-8&quot;);
        requestSend.headers.add(&quot;Authorization&quot;, auth);
        print(req);
        requestSend.write(envalue);
        return requestSend.close();
      }).then((HttpClientResponse response) async {
        print(await response.contentLength);
        var resStream = response.transform(Utf8Decoder());
        await for (var data in resStream) {
          print(&#39;Received data: $data&#39;);
          contents.write(data);
        }
        print(await response.statusCode);


      }).catchError((e) {
        print(&quot;Request error: $e&quot;); // The only case
      });

      print(contents);
//      var filValue = contents.toString();
      return Response.ok(contents);
    });

at this line return Response.ok(contents.toString()) I am getting json cast exception

here is the exception that I am getting, inserted of getting this exception it should send JSON back to calling postman:

[SEVERE] aqueduct: POST /uploadurl 1047ms 500 {user-agent : Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.88 Safari/537.36\nconnection : keep-alive\
ncache-control : no-cache\npostman-token : 8ba3e1e9-38c7-37ac-da97-5bb3de983622\naccept-encoding : gzip, deflate, br\ncontent-type : application/json\nsec-fetch-site : cross-site\naccept : */*\nsec-fe
tch-mode : cors\naccept-language : en-US,en;q=0.9\norigin : chrome-extension://fhbjgbiflinjbdggehcddcbncdddomop\ncontent-length : 103\nhost : localhost:8888\n}  Converting object to an encodable objec
t failed: Instance of &#39;StringBuffer&#39; #0      _JsonStringifier.writeObject (dart:convert/json.dart:649:7)
#1      _JsonUtf8Stringifier.stringify (dart:convert/json.dart:902:17)
#2      JsonUtf8Encoder.convert (dart:convert/json.dart:371:26)
#3      _FusedConverter.convert (dart:convert/converter.dart:69:48)
#4      Codec.encode (dart:convert/codec.dart:23:32)
#5      Request._responseBodyBytes (package:aqueduct/src/http/request.dart:340:18)
#6      Request.respond (package:aqueduct/src/http/request.dart:251:14)
#7      Controller._sendResponse (package:aqueduct/src/http/controller.dart:339:20)
#8      Controller.receive (package:aqueduct/src/http/controller.dart:176:17)
&lt;asynchronous suspension&gt;
#9      Controller.receive (package:aqueduct/src/http/controller.dart:206:28)
&lt;asynchronous suspension&gt;
#10     Router.receive (package:aqueduct/src/http/router.dart:139:18)
#11     _RootZone.runUnaryGuarded (dart:async/zone.dart:1316:10)
#12     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:338:11)
#13     _BufferingStreamSubscription._add (dart:async/stream_impl.dart:265:7)
#14     _ForwardingStreamSubscription._add (dart:async/stream_pipe.dart:134:11)
#15     _MapStream._handleData (dart:async/stream_pipe.dart:234:10)
#16     _ForwardingStreamSubscription._handleData (dart:async/stream_pipe.dart:166:13)
#17     _RootZone.runUnaryGuarded (dart:async/zone.dart:1316:10)
#18     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:338:11)
#19     _BufferingStreamSubscription._add (dart:async/stream_impl.dart:265:7)
#20     _SyncStreamControllerDispatch._sendData (dart:async/stream_controller.dart:766:19)
#21     _StreamController._add (dart:async/stream_controller.dart:642:7)
#22     _StreamController.add (dart:async/stream_controller.dart:588:5)
#23     _HttpServer._handleRequest (dart:_http/http_impl.dart:2828:19)
#24     new _HttpConnection.&lt;anonymous closure&gt; (dart:_http/http_impl.dart:2586:19)
#25     _RootZone.runUnaryGuarded (dart:async/zone.dart:1316:10)
#26     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:338:11)
#27     _BufferingStreamSubscription._add (dart:async/stream_impl.dart:265:7)
#28     _SyncStreamControllerDispatch._sendData (dart:async/stream_controller.dart:766:19)
#29     _StreamController._add (dart:async/stream_controller.dart:642:7)
#30     _StreamController.add (dart:async/stream_controller.dart:588:5)
#31     _HttpParser._headersEnd (dart:_http/http_parser.dart:388:17)
#32     _HttpParser._doParse (dart:_http/http_parser.dart:703:15)
#33     _HttpParser._parse (dart:_http/http_parser.dart:320:7)
#34     _HttpParser._onData (dart:_http/http_parser.dart:812:5)
#35     _RootZone.runUnaryGuarded (dart:async/zone.dart:1316:10)
#36     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:338:11)
#37     _BufferingStreamSubscription._add (dart:async/stream_impl.dart:265:7)
#38     _SyncStreamControllerDispatch._sendData (dart:async/stream_controller.dart:766:19)
#39     _StreamController._add (dart:async/stream_controller.dart:642:7)
#40     _StreamController.add (dart:async/stream_controller.dart:588:5)
#41     _Socket._onData (dart:io-patch/socket_patch.dart:1831:41)
#42     _RootZone.runUnaryGuarded (dart:async/zone.dart:1316:10)
#43     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:338:11)
#44     _BufferingStreamSubscription._add (dart:async/stream_impl.dart:265:7)
#45     _SyncStreamControllerDispatch._sendData (dart:async/stream_controller.dart:766:19)
#46     _StreamController._add (dart:async/stream_controller.dart:642:7)
#47     _StreamController.add (dart:async/stream_controller.dart:588:5)
#48     new _RawSocket.&lt;anonymous closure&gt; (dart:io-patch/socket_patch.dart:1379:33)
#49     _NativeSocket.issueReadEvent.issue (dart:io-patch/socket_patch.dart:899:14)
#50     _microtaskLoop (dart:async/schedule_microtask.dart:43:21)
#51     _startMicrotaskLoop (dart:async/schedule_microtask.dart:52:5)
#52     _runPendingImmediateCallback (dart:isolate-patch/isolate_patch.dart:118:13)
#53     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:175:5)

and this is the data that I got from the third-party API that I am trying to send from my rest API as a response:

{&quot;objectUrls&quot;:[{&quot;signedUrl&quot;:&quot;https://example.com&quot;,&quot;path&quot;:&quot;folder3/sub1/mysensordata.log&quot;}]}

答案1

得分: 0

以下是您提供的代码的翻译：

在阅读了一些互联网上的博客之后，我找到了一种方法：

@override
Controller get entryPoint {
  final router = Router();
  HttpClientResponse responseTemp;

  // 建议使用`link`而不是`linkFunction`。
  // 参见：https://aqueduct.io/docs/http/request_controller/
  router.route("/uploadurl").linkFunction((request) async {
    final req = await request.body.decode();
    final envalue = json.encode(req);

    HttpClient client = new HttpClient();
    client.badCertificateCallback =
        ((X509Certificate cert, String host, int port) => true);
    var auth = 'Bearer ' +
        'eyJ...';

    await client
        .postUrl(Uri.parse('http://example.com/v2/5e104a9235000079001e68e7'))
        .then((HttpClientRequest requestSend) {
      requestSend.headers
          .add("Content-Type", "application/json; charset=UTF-8");
      requestSend.write(envalue);
      return requestSend.close();
    }).then((HttpClientResponse response) async {
      responseTemp = response;
    }).catchError((e) {
      print("Request error: $e"); // 唯一的情况
    });

    await for (var contents in responseTemp.transform(Utf8Decoder())) {
      print(contents);
      return Response.ok(json.decode(contents.toString()));
    }
    return Response.noContent();
  });

  router.route("/secondurl").linkFunction((request) async {
    return Response.ok({"key": "adf"});
  });
  return router;
}

这对我有用。

英文:

After reading some blogs on the internet I found a way :

@override
  Controller get entryPoint {
    final router = Router();
    HttpClientResponse responseTemp;

    // Prefer to use `link` instead of `linkFunction`.
    // See: https://aqueduct.io/docs/http/request_controller/
    router.route(&quot;/uploadurl&quot;).linkFunction((request) async {
      final req = await request.body.decode();
      final envalue = json.encode(req);

      HttpClient client = new HttpClient();
      client.badCertificateCallback =
          ((X509Certificate cert, String host, int port) =&gt; true);
      var auth = &#39;Bearer &#39; +
          &#39;eyJ...&#39;;

      await client
          .postUrl(Uri.parse(&#39;http://example.com/v2/5e104a9235000079001e68e7&#39;))
          .then((HttpClientRequest requestSend) {
        requestSend.headers
            .add(&quot;Content-Type&quot;, &quot;application/json; charset=UTF-8&quot;);
        requestSend.write(envalue);
        return requestSend.close();
      }).then((HttpClientResponse response) async {
        responseTemp = response;
      }).catchError((e) {
        print(&quot;Request error: $e&quot;); // The only case
      });

      await for (var contents in responseTemp.transform(Utf8Decoder())) {
        print(contents);
        return Response.ok(json.decode(contents.toString()));
      }
      return Response.noContent();
    });

    router.route(&quot;/secondurl&quot;).linkFunction((request) async {
      return Response.ok({&quot;key&quot;: &quot;adf&quot;});
    });
    return router;
  }

This is working for me.

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发送响应给Postman，来自Dart Aqueduct后端。

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