# Migrating from NServiceBus.MongoDB

<!-- Version variant: mongodb_2; default: [/persistence/mongodb/migrating-from-sbmako.md](/persistence/mongodb/migrating-from-sbmako.md) -->


This package was designed to be fully compatible with the community [`NServiceBus.MongoDB`](https://github.com/sbmako/NServiceBus.MongoDB) package with some minor configuration.

> [!CAUTION]
> Compatibility with existing data requires additional settings which must be configured, otherwise data duplication and incorrect execution of business logic may occur.


## NServiceBus upgrade

`NServiceBus.Storage.MongoDB` is available for NServiceBus Version 7 and later. It is recommended to upgrade endpoints to NServiceBus Version 7 before migrating to the `NServiceBus.Storage.MongoDB` package.

## Saga data class changes

[Saga data classes](/nservicebus/sagas/index.md#long-running-means-stateful) no longer need to implement [`IHaveDocumentVersion`](https://github.com/sbmako/NServiceBus.MongoDB#sagas). If the saga data class extends [`ContainMongoSagaData`](https://github.com/sbmako/NServiceBus.MongoDB#sagas), it no longer needs to do so. In cases where `IHaveDocumentVersion` has been explicitly implemented by the saga data class, the `DocumentVersion` and `ETag` properties may be safely removed from saga data class implementations.

```diff

- class MySagaData : IContainSagaData, IHaveDocumentVersion
+ class MySagaData : IContainSagaData
{
	public Guid Id { get; set; }
	public string OriginatingMessageId { get; set; }
	public string Originator { get; set; }
-       public int DocumentVersion { get; set; }
-       public int ETag { get; set; }
}

```

If the `ETag` property is not removed, it will no longer be updated by the persister.

### Saga data compatibility mode

Use the following compatibility API to configure the package to work with existing saga data:

<!-- snippet: MongoDBSBMakoCompatibility -->

```cs
var persistence = endpointConfiguration.UsePersistence<MongoPersistence>();
var compatibility = persistence.CommunityPersistenceCompatibility();
compatibility.CollectionNamingConvention(type => type.Name);
compatibility.VersionElementName("DocumentVersion");
```

<!-- endsnippet -->

The `VersionElementName` value must match the element name used for the `DocumentVersion` property from the community persister.

> [!WARNING]
> The version element name must be set taking into account any [member mapping conventions](https://www.mongodb.com/docs/drivers/csharp/current/fundamentals/serialization/class-mapping/) configured for the MongoDB client.

In addition, the collection naming convention for sagas must be configured to match the one used by `NServiceBus.MongoDB`, `type => type.Name`, as demonstrated in the above snippet.

## Subscriptions

Subscriptions are recreated by restarting the subscribing endpoints. Alternatively, existing subscriptions can be migrated to the new data format.

## Migrating subscriptions

In the [Carlos Sandoval](https://github.com/sbmako) implementation, subscriptions are stored in the collection named `Subscription`. Each document maps to an event type containing a set of subscribers using the type `Subscriber` from the NServiceBus package.

The following migration script iterates through the documents and inserts each subscriber value as a new document.

```javascript
db.subscription.find().forEach(type => {
   type.Subscribers.forEach(subscription => {
       db.eventsubscription.insert({
           MessageTypeName: type._id.TypeName,
           TransportAddress: subscription.TransportAddress,
           Endpoint: subscription.Endpoint
       });
   });
});
```