title: mongodb Can't use $and with String
body: <p>I am not an expert with mongodb so I am tackling a searching issue using regex.</p>
  
  <p>My document called Post is structured like this :</p>
  
  <pre><code>{
    _id : String,
    keywords : [{
      timesFound : Number,
      keyword : String
    }]
  }
  </code></pre>
  
  <p>As input I have an array of potential keywords, eg: ["apple","orange"].
  How can I search all documents that match /apple/i AND /orange/i ?</p>
  
  <p>I have tried a query like this :</p>
  
  <pre><code>{"keywords.keyword" : $and: [{$regex: /apple/i}, {$regex: /orange/i}]}}
  </code></pre>
  
  <p>but got this error "Can't use $and with String."</p>
  
  <p>Do you have any ideas ?
  Thanks !!</p>