title: Dart exception: class String has no instance method '>'
body: <p>Im writting a simple class to manage database queries using sqljocky. The code is the following</p>
  
  <pre class="lang-dart prettyprint-override"><code>import 'package:sqljocky/sqljocky.dart';
  
  import 'Config.dart';
  
  abstract class QueryResultCallBack {
    void handleQuery(dynamic queryResult);
  }
  
  class DatabaseFactory {
  
    static DatabaseFactory INSTANCE;
  
    static DatabaseFactory getInstance() {
      if(INSTANCE == null)
        INSTANCE = new DatabaseFactory();
  
      return INSTANCE;
    }
  
    var dbpool;
  
    DatabaseFactory() {
      if(Config.DB_PWD.length == 0) {
        dbpool = new ConnectionPool(host: Config.DB_HOST, port: Config.DB_PORT, user: Config.DB_USER, db: Config.DB_NAME, max: Config.DB_CONNECTION_POOL_SIZE);
      } else {
        dbpool = new ConnectionPool(host: Config.DB_HOST, port: Config.DB_PORT, user: Config.DB_USER, password: Config.DB_PWD, db: Config.DB_NAME, max: Config.DB_CONNECTION_POOL_SIZE);
      }
    }
  
    void executeFullQuery(String query, QueryResultCallBack callback) {
      dbpool.query(query).then((result) {
        callback.handleQuery(result);
      });
    }
  
    void executeQuery(String queryStr, List&lt;dynamic&gt; params, QueryResultCallBack callback) {
      try {
        dbpool.prepareExecute(queryStr, params).then((result) {
            callback.handleQuery(result);
        });
      } catch(e) {
        print('DatabaseFactory.executeQuery exception:\n${e}');
      }
    }
  
    void shutDown() {
      dbpool.close();
    }
  }
  </code></pre>
  
  <p>However, when a query is performed, i get the exception "class String has no instance method ')'. The stack trace shows it is thrown here:</p>
  
  <pre><code>dbpool.prepareExecute(queryStr, params).then((result) {
  </code></pre>
  
  <p>I've searched throught the internet and most cases were this kind of error was throw a bug with a package, but didnt find any case where it happen to class String. Any ideas?</p>
  
  <p>Thanks in advance</p>
  
  <p>EDIT: Stacktrace</p>
  
  <pre><code>Uncaught Error: Class 'String' has no instance method '&gt;'.
  
  NoSuchMethodError : method not found: '&gt;'
  Receiver: "5"
  Arguments: [0]
  Stack Trace:
  #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:45)
  #1      int.&lt; (dart:core-patch/integers.dart:72)
  #2      ConnectionPool._getConnection (package:sqljocky/src/connection_pool.dart
  :64:29)
  #3      Query._getConnection (package:sqljocky/src/query.dart:35:32)
  #4      Query._prepare (package:sqljocky/src/query.dart:41:26)
  #5      ConnectionPool.prepare (package:sqljocky/src/connection_pool.dart:242:26
  )
  #6      ConnectionPool.prepareExecute (package:sqljocky/src/connection_pool.dart
  :310:19)
  #7      DatabaseFactory.executeQuery (file:///C:/Users/Nadir/Downloads/dart/dart
  -sdk/bin/prueba/DatabaseFactory.dart:46:28)
  #8      main.&lt;anonymous closure&gt;.&lt;anonymous closure&gt; (file:///C:/Users/Nadir/Dow
  nloads/dart/dart-sdk/bin/prueba/Server.dart:27:49)
  #9      _rootRunUnary (dart:async/zone.dart:717)
  #10     _RootZone.runUnary (dart:async/zone.dart:854)
  #11     _BaseZone.runUnaryGuarded (dart:async/zone.dart:569)
  #12     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:333)
  
  #13     _BufferingStreamSubscription._add (dart:async/stream_impl.dart:263)
  #14     _StreamController&amp;&amp;_SyncStreamControllerDispatch._sendData (dart:async/s
  tream_controller.dart:529)
  #15     _StreamController._add (dart:async/stream_controller.dart:438)
  #16     _StreamController.add (dart:async/stream_controller.dart:395)
  #17     _HttpServer._handleRequest (http_impl.dart:2116)
  #18     _HttpConnection._HttpConnection.&lt;anonymous closure&gt; (http_impl.dart:1954
  )
  #19     _rootRunUnary (dart:async/zone.dart:717)
  #20     _RootZone.runUnary (dart:async/zone.dart:854)
  #21     _BaseZone.runUnaryGuarded (dart:async/zone.dart:569)
  #22     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:333)
  
  #23     _BufferingStreamSubscription._add (dart:async/stream_impl.dart:263)
  #24     _StreamController&amp;&amp;_SyncStreamControllerDispatch._sendData (dart:async/s
  tream_controller.dart:529)
  #25     _StreamController._add (dart:async/stream_controller.dart:438)
  #26     _StreamController.add (dart:async/stream_controller.dart:395)
  #27     _HttpParser._doParse (http_parser.dart:687)
  #28     _HttpParser._parse (http_parser.dart:343)
  #29     _onData (http_parser.dart:813)
  #30     _rootRunUnary (dart:async/zone.dart:717)
  #31     _RootZone.runUnary (dart:async/zone.dart:854)
  #32     _BaseZone.runUnaryGuarded (dart:async/zone.dart:569)
  #33     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:333)
  
  #34     _BufferingStreamSubscription._add (dart:async/stream_impl.dart:263)
  #35     _StreamController&amp;&amp;_SyncStreamControllerDispatch._sendData (dart:async/s
  tream_controller.dart:529)
  #36     _StreamController._add (dart:async/stream_controller.dart:438)
  #37     _StreamController.add (dart:async/stream_controller.dart:395)
  #38     _onData (dart:io-patch/socket_patch.dart:1356)
  #39     _rootRunUnary (dart:async/zone.dart:717)
  #40     _RootZone.runUnary (dart:async/zone.dart:854)
  #41     _BaseZone.runUnaryGuarded (dart:async/zone.dart:569)
  #42     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:333)
  
  #43     _BufferingStreamSubscription._add (dart:async/stream_impl.dart:263)
  #44     _StreamController&amp;&amp;_SyncStreamControllerDispatch._sendData (dart:async/s
  tream_controller.dart:529)
  #45     _StreamController._add (dart:async/stream_controller.dart:438)
  #46     _StreamController.add (dart:async/stream_controller.dart:395)
  #47     _RawSocket._RawSocket.&lt;anonymous closure&gt; (dart:io-patch/socket_patch.da
  rt:948)
  #48     multiplex (dart:io-patch/socket_patch.dart:604)
  #49     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dar
  t:115)
  
  
  Unhandled exception:
  Class 'String' has no instance method '&gt;'.
  
  NoSuchMethodError : method not found: '&gt;'
  Receiver: "5"
  Arguments: [0]
  #0      _rootHandleUncaughtError.&lt;anonymous closure&gt;.&lt;anonymous closure&gt; (dart:a
  sync/zone.dart:700)
  #1      _asyncRunCallbackLoop (dart:async/schedule_microtask.dart:23)
  #2      _asyncRunCallback (dart:async/schedule_microtask.dart:32)
  #3      _asyncRunCallback (dart:async/schedule_microtask.dart:36)
  #4      _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dar
  t:119)
  </code></pre>