Golang and MongoDB - I try to update toggle boolean using golang to mongodb but got object instead

Question

I used to implement todo application using React and Nodejs. The toggle function in React and Nodejs to update Mongodb database as following code:

const toggleChecked = ({ _id, isChecked }) => {
  TasksCollection.update(_id, {
    $set: {
      isChecked: !isChecked
    }
  })
};

I would like to implement toggle function in Golang to update boolean field, but I got object instead, the following is golang code:

func updateOneMovie(movieId string) model.Netflix {
    id, _ := primitive.ObjectIDFromHex(movieId)
    filter := bson.M{"_id": id}
    update := bson.M{"$set": bson.M{"watched": bson.M{"$not": "$watched"}}}
    var updateResult model.Netflix

    result, err := collection.UpdateOne(context.Background(), filter, update)

    err = collection.FindOne(context.Background(), filter).Decode(&updateResult)

    if err != nil {
        log.Fatal(err)
    }

    fmt.Println(result)
    return updateResult
}

The result in Mongodb updates as the object instead of boolean. How can I fix to make it update toggle boolean?

Answer 1

Passing a single document (e.g. bson.M or bson.D) as the update document, field names and values will be interpreted as-is (literally).

To use aggregation pipelines with updates, you must pass an array as the update document, this is what triggers interpreting it as an aggregation pipeline. This is the only requirement. The array may be mongo.Pipeline, bson.A, []bson.D, []bson.M or even []any, it doesn't matter, it just must be an array or slice in Go. The elements may be bson.M, bson.D or any other values representing a document.

So the simplest solution:

filter := bson.M{"_id": id}
update := []any{
    bson.M{"$set": bson.M{"watched": bson.M{"$not": "$watched"}}}
}