When using RollingInternal, Collection without TimeFormat is generated

[ntark]

For example, when configuring
.WriteTo.MongoDBBson(connectionString, "logs", rollingInterval: RollingInterval.Month)

Collection with name "logs" is created, since configuration.CollectionName parameter gets passed to VerifyCollectionExists, which in turn creates said collection.

Afterwards, on first insert, "logs_202509" is generated as expected, but empty "logs" collection persists.

[kkman021]

This issue also causes the Index created after setting Interval and then SetExpireTTL to be established on the wrong Collection. This PR will also fix this error.

The index will create at user_login_events collection and it incorrect.

Setting

Result

[ntark]

@Jaben Concerning the TTL Expiration:
It seems inserting to non-existing collection automatically creates it, else current implementation would never work.
But in case of TTL index, while currently its never created for the correct table, after this PR it will only be created (or verified) on startup and when Collection Name rolls to the next value there wont be a TTL index on the new collection, until the next restart.

Two solutions I could quickly think of were to

1. create/verify that index before each insert (bad)
2. keep track of when collection name changes and create/verify it only on changes (possibly unnecessarily complicated)

I also can't think of a reason you would want TTL Index while using rolling intervals.
@kkman021 Your example keeps only last minute of logs while creating a new collection each day while also leaving empty collections. Is that just an imaginary example or are there any benefits in such configuration?

[kkman021]

@ntark It's just a imaginary example, i just trying do some setting with POC
In the feature i will try to intervals for month and set TTL for 6 month. Not sure it is good idea or not