Update random array value of elements on the collection

Question

I have a dataset of 1700 entries which have entries like this:

{
    "_id" : ObjectId("5a7acda13b808dbed05d6505"),
    "name" : "Nil",
    "symbol" : "@A",
    "isin" : "47",
    "group" : "Nil",
    "sector" : "Nil",
    "tagcounter" : 0
},
{
    "_id" : ObjectId("5a7acda13b808dbed05d6506"),
    "name" : "Nil",
    "symbol" : "@B",
    "isin" : "48",
    "group" : "Nil",
    "sector" : "Nil",
    "tagcounter" : 0
},
{
    "_id" : ObjectId("5a7acda13b808dbed05d6507"),
    "name" : "Nil",
    "symbol" : "@C",
    "isin" : "49",
    "group" : "Nil",
    "sector" : "Nil",
    "tagcounter" : 0
}//.....upto 1700 entries

Now I have an array which has some value like this:

var array = ['Fruit', 'Vegetable', 'Drinks', 'Fast-Food', 'Healthy-Food'];

Now I want to update entire sector values from "Nil" to "Any value From array". The expected result will be like this:

{
    "_id" : ObjectId("5a7acda13b808dbed05d6505"),
    "name" : "Nil",
    "symbol" : "@A",
    "isin" : "47",
    "group" : "Nil",
    "sector" : "Fruit",
    "tagcounter" : 0
},
{
    "_id" : ObjectId("5a7acda13b808dbed05d6506"),
    "name" : "Nil",
    "symbol" : "@B",
    "isin" : "48",
    "group" : "Nil",
    "sector" : "Drinks",
    "tagcounter" : 0
},
{
    "_id" : ObjectId("5a7acda13b808dbed05d6507"),
    "name" : "Nil",
    "symbol" : "@C",
    "isin" : "49",
    "group" : "Nil",
    "sector" : "Fast-Food",
    "tagcounter" : 0
}

What I did for this is:

db.Collection.update({},{$set: {'sector': ['Fruit', 'Vegetable', 'Drinks', 'Fast-Food', 'Healthy-Food']}}, {multi: true }, function(error, data){
  if( error) {
    console.log(error);
  } else {
    console.log(data);
  }
});

But by this, The Entire Array is copied on every field rather than one value.

I know there is a problem on providing the whole array.

If anyone has solution for this then please let me know.

Answer 1

db.Collection.find({}).forEach((doc) => {
  db.Collection.update({_id: doc._id}, {$set: {sector: array[Math.floor(Math.random()* array.length)]}})
})

Refer here for forEach cursor documentation.