title: Find ALL records where NO item in arrays has a value
body: <p>I want to find ALL records where NO item in EITHER array (things1 or things2) has a "color" value.
  (so ALL color are either '' or null or does not exist)</p>
  
  <p>Here is the data structure - </p>
  
  <pre><code>{
      _id: objectId(),
      things1: [
          {
              height:
              weight:
              color:
          }
      ],
      things2: [
          {
              size:
              flavor:
              color:
          }
      ]
  }
  </code></pre>
  
  <p>I have tried this:</p>
  
  <pre><code>.find({
      $and: [
          {
              things1:{ 
                  $elemMatch: { 
                      $or: [
                          {
                              color: ''
                          },
                          {
                              color: null
                          },
                          {
                              color: { $exists: false }
                          }
                      ]
                  } 
              } 
          },
          {
              things2:{ 
                  $elemMatch: { 
                      $or: [
                          {
                              color: ''
                          },
                          {
                              color: null
                          },
                          {
                              color: { $exists: false }
                          }
                      ]
                  } 
              } 
          }
      ]
  })
  </code></pre>
  
  <p>This pulls back ANY records where ANY item has a blank, null or non-existent "color"...
  meaning if there are thee things in "things1" and two of the three have a color and the third is an empty string, and all the items in "things2" have a color - the above query will return this document</p>
  
  <p>Where I want ONLY records where ALL the "color" fields are blank, null or non-existant.</p>
  
  <p>Any help appreciated
  thanks</p>