title: Mongodb - bad query: BadValue unknown top level operator: $gte
body: <p>What is wrong with this query? I tried to run it on mongodb server and received an error as following - "exception: bad query: BadValue unknown top level operator: $gte". Can anyone tell me what is wrong with it, please?</p>
  
  <pre><code>        db.scores.aggregate([ 
              { 
                  $match: { 
                      $or: [ 
                          { $gte: [ "$score", 30 ] }, 
                          { $lte: [ "$score", 60 ] } 
                      ] 
                  } 
              },
              { 
                  $group: { 
                      _id: "$gamer",
                      games: { $sum: 1 }
                  } 
              }
          ])
  </code></pre>
  
  <p>sample data :</p>
  
  <pre><code>        {
              "_id" : "545665cef9c60c133d2bce72",
              "score" : 85,
              "gamer" : "Latern"
          }
  
          /* 1 */
          {
              "_id" : "545665cef9c60c133d2bce73",
              "score" : 10,
              "gamer" : "BADA55"
          }
  
          /* 2 */
          {
              "_id" : "545665cef9c60c133d2bce74",
              "score" : 62,
              "gamer" : "BADA55"
          }
  
          /* 3 */
          {
              "_id" : "545665cef9c60c133d2bce75",
              "score" : 78,
              "gamer" : "l00ser"
          }
  
          /* 4 */
          {
              "_id" : "545665cef9c60c133d2bce76",
              "score" : 4,
              "gamer" : "l00ser"
          }
  
          /* 5 */
          {
              "_id" : "545665cef9c60c133d2bce77",
              "score" : 55,
              "gamer" : "FunnyCat"
          }
  </code></pre>