Fluent and/or NH dirty one-to-many collection strategies

[mwpowellhtx]

Hello, we would like to know what if any are the strategies reconciling a dirty one to many collection. Comparing contrasting with EntityFrameworkCore, was finding this to be the case, for example. And assuming there are sufficient cascading mappings added, perhaps also clarifying which of those cascading attributes would have the desired strategic effect.

• Adding new items, inserting those records, EF was fine with this.
• Updating existing items, EF was also fine with this.
• Removing or deleting old items, i.e. which no longer exists; was finding EF to be woefully deficient in this area; required manual top-bottom A-B comparison the P-C chain.

Wondering, is Fluent and/or NH any stronger at dealing with these use cases? Particular the third.

Cheers and thanks for the insights! 🍻

[mwpowellhtx]

I should also add, at least in our case, we are running in a completely detached environment. That is, we get or query for the instances we want, and when ready to post a change, request a new session instance, then do the appropriately top level SaveOrUpdate, including any parent-child one-to-many cascading relationships, ideally. We do not maintain any lazy loaded proxies or anything of that sort, in fact, we disable that intentionally; it is not necessary in our case.

[mwpowellhtx]

After having pushed through a couple of internal IUserType issues...

Based on these exceptions, this somewhat addresses at least one question. That is, the ORM behaviors around would-be orphaned records is problematic. Which is also consistent with EF.

Message	"One or more errors occurred. (could not delete collection rows: [WhalleyBotEnhanced.DiscordGuild.TextChannels#5473d66b-826c-481a-9b66-a065a49eb72c][SQL: UPDATE public.efcore_discord_discordtextchannel SET DiscordGuildId = null WHERE DiscordGuildId = :p0 AND Id = :p1])"	string

-	InnerException	{"could not delete collection rows: [WhalleyBotEnhanced.DiscordGuild.TextChannels#5473d66b-826c-481a-9b66-a065a49eb72c][SQL: UPDATE public.efcore_discord_discordtextchannel SET DiscordGuildId = null WHERE DiscordGuildId = :p0 AND Id = :p1]"}	System.Exception {NHibernate.Exceptions.GenericADOException}

+	InnerException	{"23502: null value in column \"discordguildid\" of relation \"efcore_discord_discordtextchannel\" violates not-null constraint\r\n\r\nDETAIL: Failing row contains (81426f97-3e64-4283-8871-2cbc286973c3, null, 1330294290244435999, ticket-126, 541461771228282882, 979812437018689587, ADMIN HELP)."}	System.Exception {Npgsql.PostgresException}

And in the database log:

2025-06-16 20:15:13.471 EDT [43452] ERROR:  null value in column "discordguildid" of relation "efcore_discord_discordtextchannel" violates not-null constraint
2025-06-16 20:15:13.471 EDT [43452] DETAIL:  Failing row contains (81426f97-3e64-4283-8871-2cbc286973c3, null, 1330294290244435999, ticket-126, 541461771228282882, 979812437018689587, ADMIN HELP).
2025-06-16 20:15:13.471 EDT [43452] STATEMENT:  UPDATE public.efcore_discord_discordtextchannel SET DiscordGuildId = null WHERE DiscordGuildId = $1 AND Id = $2

Which leads me to believe that in fact what would be orphaned records are not being handled as such. That is, in this case, literally, DiscordGuildId is literally the FK column mapping to the parent table. In this case the instance fell out of the list naturally during one of our reconcile operations with Discord, meaning the channel no longer exists, so should naturally be removed.

[mwpowellhtx]

So question now is, training our mappings, I think perhaps we signal:

Not.Lazy();
Never.Cache();

For starters.

Thoughts?