Many of us would have already used MongoDB for storing data as Documents. However, I come from a world of SQL where everything is stored in Tables following the Normalization process. Hence, anything that can be further broken down, should be considered storing in a separate table.
In the world of MongoDB or rather, No-SQL, we do not have anything like that. Here, the more connected the data is supposed to have, the more chances of storing them together makes sense. Let’s look at the below example:
{
"_id":"d5ebb427",
"name":"Anubhav Ranjan",
"email":"email@gmail.com",
"subscriptions":[
{
"subscriptionId":"1abc",
"showId":"d060b8ca",
"notificationEnabled":true
},
{
"subscriptionId":"2abc",
"showId":"d060b8cb",
"notificationEnabled":true
}
]
}
Let’s consider the code snippet above. I have an object User having Two Subscriptions. Now I want to make one of the Subscriptions as false. This should be done using C#.
Let’s see how this can be achieved using Mongo shell
db.users.find({ _id: "d5ebb427", "subscriptions.subscriptionId":"1abc"});
db.users.update({ _id: "d5ebb427", "subscriptions.subscriptionId":"1abc"}, { $set: {"subscriptions.$.notificationEnabled": false}});
Let’s go ahead and check out the C# implementation
// C# Mongo Schema
public class User
{
[BsonId]
public string Id { get; set; }
[BsonElement("name")]
public string Name { get; set; }
[BsonElement("email")]
public string Email { get; set; }
[BsonElement("subscriptions")]
public Subscription[] Subscriptions { get; set; }
}
public class Subscription
{
[BsonElement("subscriptionId")]
public string SubscriptionId{ get; set; }
[BsonElement("showId")]
public string ShowId { get; set; }
[BsonElement("notificationEnabled")]
public bool NotificationEnabled { get; set; }
}
In order to do this, we are using the positional $ operator.
As per the MongoDB docs, The positional $ operator identifies an element in an array to update without explicitly specifying the position of the element in the array.
var filter = Builders.Filter;
var userSubscriptionFilter = filter.And(
filter.Eq(u => u.Id, id),
filter.ElemMatch(u => u.Subscriptions, s => s.SubscriptionId == subId)
);
// Find User with Id and Subscription Id
var user = await usersCollection.Find(userSubscriptionFilter).SingleOrDefaultAsync();
// Update using the positional operator
var update = Builders.Update;
var subscriptinonSetter = update.Set("subscriptions.$.notificationEnabled", false);
var updateResult = await usersCollection.UpdateOneAsync(userSubscriptionFilter, subscriptinonSetter);
After further reading, I have even found that you can change the line from this:
var subscriptinonSetter = update.Set("subscriptions.$.notificationEnabled", false);
to this:
var subscriptinonSetter = update.Set(s => s.Subscriptions[-1].NotificationEnabled, false);
Happy Coding!
