Add support for `remote` on fields

[banool]

Hey, I just took a look at modifying poem-openapi-derive/src/object.rs but I couldn't quite figure out what to do.

What I'd love to be able to do is something like this:

#[derive(Object)]
struct MyStruct {
    a: u32,
    #[oai(remote = "u32")]
    b: u64,
}

This is just an example, in reality the type I use in remote would be a local version of a remote type, so I can impl the Poem stuff on it.

I want this because today if I wanted to do this, I would have to add remote to the whole struct instead and define a whole new wrapper struct, even though I only want this for one field.

I suppose in some ways this is similar to https://github.com/poem-web/poem/issues/322. My ultimate goal is I have a newtype in a remote crate that I don't want to have to wrap, since I use it in many places.

[sunli829]

Do you want the code below to work?

InternalMyObj has a and b fields, but MyObj has only a field.

    mod remote {
        #[derive(Debug, Eq, PartialEq)]
        pub struct InternalMyObj {
            pub a: i32,
            pub b: String,
        }
    }

    #[derive(Debug, Object, Eq, PartialEq)]
    #[oai(remote = "remote::InternalMyObj")]
    struct MyObj {
        a: i32,
    }

[banool]

Hmm not quite, what I really want is something like this: https://github.com/poem-web/poem/issues/322. This code explains what I want better:

    mod remote {
        #[derive(Debug, Eq, PartialEq)]
        pub struct Address(pub String);
    }

    #[derive(Debug, Eq, PartialEq, NewType)]
    struct AddressHelper(pub String);

    impl From<remote::Address> for AddressHelper {
        fn from(address: remote::Address) -> Self {
            Self(address.0)
        }
    }

    impl Into<remote::Address> for AddressHelper {
        fn into(self) -> remote::Address {
            remote::Address(self.0)
        }
    }


    #[derive(Debug, Object, Eq, PartialEq)]
    struct MyObj {
        #[oai(serializer_type = AddressHelper)]
        address: Address,
        value: u32,
    }

For this serializer_type should be a struct that implements Into<T>, From<T> like how in the above example AddressHelper does. It should also impl the traits that allow it to be used in a Poem object, like ParseFromJSON, ParseFromParameter, ToJSON, etc. AKA all the traits that you get when you add a Poem derive like NewType.

The purpose of this is I can now use Address in my poem type even though I am not able to derive a Poem trait on it.

This is pretty much a clearer description of https://github.com/poem-web/poem/issues/322, so let me know if you want me to close this issue and we migrate to that one.

[sunli829]

There is a problem with ownership here, when calling Address::ToJson, need to convert Address to AddressHelper, which will transfer ownership, unless Address implements Clone.

[banool]

I think that's an acceptable bound to have if you want to use this feature. I'll look at the traits some more to make sure I understand what you're talking about though.

[sunli829]

Maybe you can use AddressHelper directly?

    #[derive(Debug, Object, Eq, PartialEq)]
    struct MyObj {
        address: AddressHelper,
        value: u32,
    }

[banool]

The problem is I have like 100 places where I use the original Address, so that's a lot of refactoring, plus I interact with other crates that I don't control that expect that type. So for now I'm using a wrapper and a lot of .into() (which has the same problem where I have to replace those 100 places with different usage, but at least I don't have to change crates I don't own).

[sunli829]

Although there are many places to add .into(), at least the compiler will tell you where to add it, is this a one-time job? 😂

[banool]

Yeah one time job lol, probably not worth your effort to add right now hahah. A nice feature for the future perhaps.

[banool]

Okay more than a one time job, wrapping everything is becoming a bit painful. It's okay for now though.

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This issue is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 5 days.

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