How to add object to the array in mongodb

Question

type Student struct {
    ID           primitive.ObjectID   `bson:"_id,omitempty"`
    ...
    Users      []primitive.ObjectID `json:"users"`
    ...
}

I have this struct and I want to add to Users array. I'm doing this and I'm using Mongo-go-driver

// Filter for search
filter := bson.M{"_id": userID}

// Fields to update
update := bson.M{"$addToSet": bson.M{"users": ID}}

// Update the document
UsersCollection := GetUsersCollection()
UsersCollection.FindOneAndUpdate(context.Background(), filter, update, nil)

Can somebody tell me what I'm doing wrong? It's not adding to the database it's staying null.

Kamol Hasan · Accepted Answer · 2019-09-28 22:27:18Z

1

Change suggestions:

Change structure metadata tag json to bson

type Student struct {
    ID           primitive.ObjectID   `bson:"_id,omitempty"`
    ...
    Users      []primitive.ObjectID   `bson:"users"`
    ...
}

edited Sep 28, 2019 at 22:27

answered Sep 28, 2019 at 21:38

Kamol Hasan

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2 Comments

OhhhThatVarun Over a year ago

It's not working. I did this var values = []primitive.ObjectID{ID}

Kamol Hasan Over a year ago

@VarunRaj have you tried using single value like your example? that also failed?

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