Best practices when reading stored data

[musjj]

Say I have a EmailAddress newtype that I use to validate incoming requests before inserting them to the database. Now I want to read them back from the database, I have three choices:

• Use the new_unchecked method. This will litter all my code with misleadingly scary unsafe { ... } blocks.
• Use the try_new method. This means that additional, wasteful overhead will be incurred for every read. This also introduces a new error path that I have to take into account and propagate in all my function signatures.
• Use raw types (e.g. String, u32, etc.). This is what I do right now, but I definitely don't feel satisfied with it.

There's a similar discussion about it in the rust-lang forum: https://users.rust-lang.org/t/a-newtype-that-has-a-constructor-but-also-a-trusted-way-to-bypass-the-constructor/68593

I'm also thinking of having a separate struct (e.g. EmailAddressUnchecked?) that performs no validation, but it doesn't feel idiomatic.

[greyblake]

@musjj Sorry, I've missed your message before.

I would highly recommend using EmailAddress::try_new() and either panic or handle an error is a more graceful way.
Typically a runtime cost is not high. And if it fails (assuming you have a monitoring in place) you want to be notified if you have invalid data in DB.

If performance is really so critical for you (often it's not a case for rust web apps, because they're already sufficiently fast), you should consider using new_unchecked (that's the reason why it exists after all).

Introducing a type like EmailAddressUnchecked can also be an option.. though, it may also introduce more problems to your code base as well.