Put Javascript Array Values into Mongodb Collection Values

Question

I have a Javascript Array filled with mean Values and I want to insert them into a collection with a field named "mean". The Field "mean" already exists and has already values in them and now I want to update them with the values of the Array. To be more specific: I want the first Value of the Array to be in the first Document under the field "mean" and so on. I have 98 Documents and the Array has also a length of 98.

The Collection looks like this with the name "cmean":

{ 
    "_id" : "000", 
    "mean" : 33.825645389680915

}
{ 
    "_id" : "001", 
    "mean" : 5.046005719077798 

}

and the Array:

[
    33.89923155012405, 
    5.063347068609219
]

lastedit?? what syntax is this ? use find in update?

Nozar Safari
– Nozar Safari

2018-03-15 12:40:36 +00:00
Commented Mar 15, 2018 at 12:40 — Nozar Safari
– Nozar Safari, Commented Mar 15, 2018 at 12:40
@chridam answer is right , just missing } in line4

Nozar Safari
– Nozar Safari

2018-03-15 12:44:02 +00:00
Commented Mar 15, 2018 at 12:44 — Nozar Safari
– Nozar Safari, Commented Mar 15, 2018 at 12:44
Check the updated answer

chridam
– chridam

2018-03-15 13:25:47 +00:00
Commented Mar 15, 2018 at 13:25 — chridam
– chridam, Commented Mar 15, 2018 at 13:25
@chridam Works perfectly. Thank you so much. :)

Victor W.
– Victor W.

2018-03-15 13:32:19 +00:00
Commented Mar 15, 2018 at 13:32 — Victor W.
– Victor W., Commented Mar 15, 2018 at 13:32

chridam · Accepted Answer · 2018-03-15 14:18:16Z

3

You can use the forEach method on the array to iterate it and update the collection. Use the index to get the _id to be used in the update query, something like the following:

meansArray.forEach(function(mean, idx) {
    var id = db.cmean.find({}).skip(idx).limit(1).toArray()[0]["_id"];
    db.cmean.updateOne(
        { "_id": id },
        { "$set": { "mean": mean } },
        { "upsert": true }
    );
});

For large collections, you can streamline your db performance using bulkWrite as follows:

var ops = [];

meansArray.forEach(function(mean, idx) {
    var id = db.cmean.find({}).skip(idx).limit(1).toArray()[0]["_id"];
    ops.push({
        "updateOne": {
            "filter": { "_id": id },
            "update": { "$set": { "mean": mean } },
            "upsert": true            
        }
    });

    if (ops.length === 1000 ) {
        db.cmean.bulkWrite(ops);
        ops = [];
    }
})

if (ops.length > 0)
    db.cmean.bulkWrite(ops);

edited Mar 15, 2018 at 14:18

answered Mar 15, 2018 at 11:10

chridam

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2 Comments

chridam Over a year ago

Are all the _id's zero padded?

Victor W. Over a year ago

No after the zeroes there are names

Marek · Accepted Answer · 2018-03-15 11:06:12Z

0

update({"_id": id}, $set: {"mean": myArray}, function(res, err) { ... });

If you are using mongoose, you also have to change data model from string to array.

edited Mar 15, 2018 at 11:06

answered Mar 15, 2018 at 10:55

Marek

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