MongoDB – 配列からフィールドを削除する

> db.hosting.findOne();
{
      "__id" : 39,
      "domain" : "mkyong.com",
      "countryStat" :[         {
                 "countryCode" : "us",
                 "countryName" : "United States",
                 "count" : 2170
         },
         {
                 "countryCode" : "il",
                 "countryName" : "Israel",
                 "count" : 22
         },

     ]}

db.hosting.find({__id: 39 }).forEach(function(doc) {

    var countries = doc.countryStat;
    for(var i = 0; i < countries.length; ++i) {
        var x = countries[i];
        delete (x["countryName"]);

    }
    db.hosting.save(doc);
});

> db.hosting.findOne();
{
      "__id" : 39,
      "domain" : "mkyong.com",
      "countryStat" :[         {
                 "countryCode" : "us",
                 "count" : 2170
         },
         {
                 "countryCode" : "il",
                 "count" : 22
         },

     ]}