title: Remove quotes from MongoDB field
body: <p>I have a MongoDB collection with many records like this</p>
  
  <pre><code>{ 
  "_id" : "500cecd97f3b198ba7aceea3",
          "startDate" : NumberLong("1343023785531"),
          "user_id" : "soggettoDGcfe",
          "app_source" : "Diary",
          "measuredValue":120,
  }
  </code></pre>
  
  <p>The problem is that due to a bug of an application, there are hundreds of records with the field "measuredValue" as a string:</p>
  
  <pre><code>{ 
  "_id" : "ab0cecd97f3176eba7aceea3",
          "startDate" : NumberLong("1343023785531"),
          "user_id" : "soggettoDGcfe",
          "app_source" : "Diary",
          "measuredValue":"76.0",
  }
  </code></pre>
  
  <p>So when i try to run some queries to check if the value is bigger than something, the record is not returned. With a query i was able to correct some records one by one </p>
  
  <pre><code>db.OBSERVABLEPARAMETER.update({_id:"500cecd97f3b198ba7aceea3"},{$set:{measuredValue:76}});
  </code></pre>
  
  <p>but they are hundreds!
  How can i update all of them rapidly?</p>