CODEWITHSUNDEEP
mongodb
Satheesh Narayanan
Satheesh Narayanan

Reputation: 321

How to make this query on mongoDB?

Here is my collection structure...

   {
       "_id": ObjectId("5316f53228551c0af600019b"),
       "age_range": {
         "min": NumberInt(21)
      },
 "likes": {
     "data": {
       "0": {
         "category": "Tv show",
         "name": "Those Who Kill on A&E",
         "created_time": "2014-03-03T15:08:02+0000",
         "id": "629689387051864"
      },
       "1": {
         "category": "Journalist",
         "name": "Robin Roberts",
         "created_time": "2014-02-24T18:02:43+0000",
         "id": "780950061932847"
      }
},
{
 "_id": ObjectId("5316f53228551c0af600019b"),
`

I need to fetch total number of users likes for each category. For example

Category Name: Journalist
Total users: 10

Upvotes: 0

Views: 67

Answers (1)

Boklucius
Boklucius

Reputation: 1926

try this (collection should be the collection that you have)

var mapFunction = function() {
    for (a in this.likes.data){
        var name = this.likes.data[a].category;
        emit(name, 1);
    }
}
var reduceFunction = function(key, val){
    return Array.sum(val);
}
db.collection.mapReduce(mapFunction, reduceFunction, {out: "myresult"});
db.myresult.find();

Upvotes: 2

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