Can we support `#[serde(with = "..")]`?

[NyxCode]

Would it make sense for us to parse #[serde(with = "..")] as an alias for #[ts(as = "..")]?

serde seems to, when encountering a field with #[serde(with = "X")], (de)serialize with X::(de)serialize.
That means that #[serde(with)] can point to a module with two functions, or two a struct implementing Serialize and Deserialize.

In the 1st case, there's nothing we can do. For case 2, however, we could interpret that as #[ts(as = "X")].

So, to support this, we'd need to figure out if X is a type or a module path. We could decide that based on capitalization (a::b::C is probably a type, and a::b::c is probably a module). If we determine that it's a module, we ignore it. If it's a type, we interpret the annotation as #[ts(as = "..")]. It's not bullet-proof, but probably good enough?

If we went down that road, it'd make sense to have #[ts(type = "..")] or #[ts(as = "..")] take prescedence over #[serde(with = "..")], overriding it.

Happy to hear any input on this!

Links

• serde docs for #[serde(with)]
• serde docs for remote types

[escritorio-gustavo]

So, to support this, we'd need to figure out if X is a type or a module path. We could decide that based on capitalization (a::b::C is probably a type, and a::b::c is probably a module).

What if instead of testing capitalization, we generated some code like fn does_this_compile() { <#ty as #crate_rename::TS>::name() }?

[NyxCode]

Does that work? If it doesn't compile, I don't think there's anything we can do about that.

[escritorio-gustavo]

That's what I'm getting at. We shouldn't be the ones deciding that through checking capitalization, we should let the compiler check if whatever the user provided is a type.

[NyxCode]

I agree that that would be peferable, but let's say we generate your does_this_compile, and it doesn't - what now?

[escritorio-gustavo]

We just let the user get the compiler error. It should be something along the lines of "expected a type, got a module" or "type does not implement TS". That should guide the user to fix the attribute

[escritorio-gustavo]

Except this needs to work with serde, which accepts a module there... forgot about that

[escritorio-gustavo]

Still, if we could change the error message to be something like "using #[serde(with = "module")] requires the #[ts(as = "type")] attribute" that would keep serde working and tell the user how to fix the problem. I don't know if that's possible though

[escritorio-gustavo]

Instead of trying to make them compatible, we could make it so using #[serde(with = "..")] demands using #[ts(as = "..")] or #[ts(type = "..")]

[NyxCode]

That'd work! The worst-case there would be that a user had to do

#[ts(as = "TypeA")]
field: TypeA

---

To be honest, I share your aversion to infering stuff from the path. It does seem unlikely to break, but relying on it is just a bit iffy.

If we're going with the "#[serde(with)] requires a type override" solution, we'll have to consider if the effort/added complexity is worth the small benifit. I'd also be fine with just closing this as wontfix.

[escritorio-gustavo]

That'd work! The worst-case there would be that a user had to do

#[ts(as = "TypeA")]
field: TypeA

I actually think this is good. In general, #[serde(with = "...")] changes the type that TypeScript will receive, so #[ts(as = "...")] should be required. If #[serde(with = "...")] doesn't change the type, the user should explicitly say that like you did in this snippet

To be honest, I share your aversion to infering stuff from the path. It does seem unlikely to break, but relying on it is just a bit iffy.

Yeah, it feels like putting way too much trust in what is, effectively, just a string.

If we're going with the "#[serde(with)] requires a type override" solution, we'll have to consider if the effort/added complexity is worth the small benifit. I'd also be fine with just closing this as wontfix.

Good point, this might actually be difficult to add, so we should be sure it's worth it

[escritorio-gustavo]

That'd work! The worst-case there would be that a user had to do

#[ts(as = "TypeA")]
field: TypeA

With #299 this can be done as

#[ts(as = "_")]
field: TypeA