update multiple documents with sub array elements in mongodb without $ operator

Question

I want to update the element of subarray with another element of same array index. Actually what mistake what I have done is typo mistake in column name (reviews, review) so want to update all reviews column with review. Can anybody give me the query to update this scenerio.

This is my document json

{
    "_id" : ObjectId("57a5df273c6c00d1378b456d"),   
    "review_time" : ISODate("2016-02-06T12:59:19.000Z"),
    "review" : "My name is Sandra P. and I am a satisfied customer. I've been working with eBrandz for a little more than two years and plan on keep doing so. They are always there whenever I have any concern and their approach is very professional. I would definitely recommend their services as I have seen great results.",
    "rating" : 5,
    "review_reply" : [ 
        {
            "author" : "http://new york.cylex usa.com/company/ebrandz inc 18441959.html",
            "reply_time" : "1969-12-31",
            "reviews" : "Sandra thanks for recommending ebrandz, appreciated."
        }, 
        {
            "author" : "http://new york.cylex usa.com/company/ebrandz inc 18441959.html",
            "reply_time" : "1969-12-31",
            "reviews" : "Sandra thanks for recommending ebrandz, appreciated.1"
        }, 
        {
            "author" : "http://new york.cylex usa.com/company/ebrandz inc 18441959.html",
            "reply_time" : "1969-12-31",
            "review" : "Sandra thanks for recommending ebrandz, appreciated22."
        }
    ],
}

Answer 1

    db.temp_reviews.find( {'review_reply.reviews' : {$exists : true}  } ).forEach( function (doc) {
          doc.review_reply.forEach(function (z) {               
        if(z.reviews){        
           z.review =   z.reviews
           delete z.reviews;
        }
          });
          db.temp_reviews.save(doc);
 });

Answer 2

Your were close, you just need to loop through your array, check if wrong field exist, create the field, delete the wrong field :

db.reviews.find({
    'review_reply.reviews': {
        $exists: true
    }
}).forEach(function(doc) {
    for (var i = 0; i < doc.review_reply.length; i++) {
        if (doc.review_reply[i].hasOwnProperty("reviews")) {
            doc.review_reply[i].review = doc.review_reply[i].reviews;
            delete doc.review_reply[i].reviews;
        }
    }
    db.reviews.save(doc);
});