Would you (or do you) use Option to model nullable database columns?

[Meigs2]

I'm designing some database models for a new project and was wondering if anyone uses Option (or similar structure) to model nullable database column types instead of using nullable reference types?

I can see the benefit of having Option directly in the model, however as someone still very new to functional programming, I feel like nullable reference types are more fitting on the raw data model, given nullable reference types in C# seem like they would more directly reflect null data on the database-side rather than Option. I think there's an easier argument for having Option on something like a DTO or command/query object with MediatR or similar.

If you do use Option (Or a similar structure) to represent null, how do you integrate these properties with ORM's like EF Core/Dapper/etc?

Thanks!

[YuriiNskyi]

I feel like nullable reference types are more fitting on the raw data model, given nullable reference types in C# seem like they would more directly reflect null data on the database-side rather than Option.

You have answered the question by yourself. EF Core and other ORM`s are intended to work with raw C# features, so there is no point trying to tie EF Core and high-level functional (unknown for him) things.

In other words, let the Option be inside your Domain, while nullable reference types remain inside Infrastructure (ORMs and so forth). Don't mix them (use Option inside Infrastructure and vice versa), it is a guaranteed way for a lot of mistakes.

So, how to connect your Domain and Infrastructure, if they use different concepts for the same abstraction? The answer is pretty simple - use mapping layer. Translations between null and Option are deadly simple using already provided by this library functionality. Additionally, mapping layer has a great advantage of reducing coupling between your layers (because sometimes layers tend to be changing out of sync of each other).

To summarize, my best advice is even beyond using Option - do not use anything such specific inside your Infrastructure layer. it's not worth it. Instead of fixing tons of compatibility issues, it is always better to avoid them at all. Raw C# is already almost perfect for such kind of tasks.

Hope that I answered your question!

[Meigs2]

Great answer. Thank you!

[alarya]

@Meigs2 - I think you might also want to check out the discussion here - issue