MongoDB - mapReduce - Object.values is not a function

Question

Here is a document example of my collection:

{
  "_id": "5a68a9308117670afc3522cd",
  "username": "user1",
  "favoriteItems": {
    "5a0c6711fb3aac66aafe26c6": {
      "_id": "5a0c6711fb3aac66aafe26c6",
      "name": "item1",
    },
    "5a0c6b83fd3eb67969316dd7": {
      "_id": "5a0c6b83fd3eb67969316dd7",
      "name": "item2",
    },
    "5a0c6b83fd3eb67969316de4": {
      "_id": "5a0c6b83fd3eb67969316de4",
      "name": "item3"
    }
  }
}

and I am using mongoDB mapReduce feature to count how many times an item is liked by users.

here are my map and reduce functions:

var mapFun = function () {
    Object.values(this.favoriteItems).forEach(item => {
        emit(item, 1)
    })
}

var redFun = function (item, values) {
    count = 0
    for(i = 0; i<values.length; i++) {
        count += values[i]
    }
    return count
}

However, I get the error Object.values is not a function:

2018-01-27T13:58:08.494+0000 E QUERY    [thread1] Error: map reduce failed:{
        "ok" : 0,
        "errmsg" : "TypeError: Object.values is not a function :\n@:2:5\n",
        "code" : 139,
        "codeName" : "JSInterpreterFailure"
}

v8.9.4 which is LTS. Do I need node 9.4.0 to use Object.values()? — Blank
– Blank, Commented Jan 27, 2018 at 14:35

Pubudu Dodangoda · Accepted Answer · 2018-01-27 14:15:37Z

3

Object.values is a ES2017 feature. Probably your NodeJs version is old and doesn't support the feature.

You can either,

Upgrade NodeJs
Use babel to transpile the code
Use Object.keys and then use the key to refer the value,

like this,

Object.keys(this.favoriteItems).forEach((key)=>{
   let value = this.favoriteItems[key]
})

answered Jan 27, 2018 at 14:15

Pubudu Dodangoda

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1 Comment

Blank Over a year ago

Thank you for the clarification. I opted for option 3 and it worked.

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