Support for repr attribute

[Naymoll]

I tried to write a simple impl support of repr attribute. Right now there is no support for serde tags.

If we have something like this:

#[derive(Debug, Clone, Serialize, Deserialize, JsonSchema, ToSchema)]
#[repr(u8)]
pub enum OsrmVersion {
    Osrm4 = 0,
    Osrm5,
}

Macro generates the following output:

impl utoipa::ToSchema for OsrmVersion {
    fn schema() -> utoipa::openapi::schema::Schema {
        utoipa::openapi::ObjectBuilder::new()
            .schema_type(utoipa::openapi::SchemaType::Integer)
            .enum_values(Some([Self::Osrm4 as u8, Self::Osrm5 as u8]))
            .into()
    }
}

*.json file

"OsrmVersion": {
    "type": "integer",
    "enum": [
        "0",
        "1"
}

Related to: #271

[Naymoll]

Also, I haven't checked how schema attributes affect macro generation.

[juhaku]

This is a pretty good start 💪 but support for serde attributes would be beneficial, but the rename of enum at container level is no prio since throughout the lib there is no such support and implementing it needs more planning. And tests would be be useful. There are plenty in schema_derive_test.rs file 🙂

[Naymoll]

I think the tag and skip attributes need to be supported from serde. The others do not make sense. I will try to write an implementation. Tests as well.

[Naymoll]

I noticed one thing. Even if the enum type is marked as integer, the value itself is still a string. So when I make a request to the server, it sends this:

"configuration": {
    ...
    "osrm_version": "0",
    ...
}

Which is incorrect:

{"error":"Json deserialize error: invalid type: string \"0\", expected u8 at line 7 column 27"}

I've already changed enum_values, so you can pass whatever that impl ToString. But I think that it's wrong. And more changes are needed. Any advice?

[juhaku]

Keep in mind that the OpenAPI specification does not allow integer type of enums. https://swagger.io/specification/ If you browse to the spec and search for enum you find that it is always used as array of string types.

[Naymoll]

Didn't know that. Then all that's left is to write the tests.

[Naymoll]

I think that's all for now.

[juhaku]

Keep in mind that the OpenAPI specification does not allow integer type of enums. https://swagger.io/specification/ If you browse to the spec and search for enum you find that it is always used as array of string types.

Sorry, I eat my words, I tested it in editor.swagger.io and seems like the enum can also be represented according the type of the field. e.g.

components:
  schemas:
    Order:
      type: object
      properties:
        status:
          type: integer
          description: Order Status
          enum:
            - 0
            - 1
            - 2

[juhaku]

I've already changed enum_values, so you can pass whatever that impl ToString. But I think that it's wrong. And more changes are needed. Any advice?

Actually to have it support dynamic enum values there is a need to change the enum_values representation within the Object type in utoipa crate.

pub struct Object {
// ...
    #[serde(rename = "enum", skip_serializing_if = "Option::is_none")]
    pub enum_values: Option<Vec<String>>,

The string needs to be changed to serde_json::Value see the example field. And then of course fix all the existing usages which currently expect it to be string.

[juhaku]

Overall this is okay there are 2 things still address here 🙂

• Add this repr create support behind a repr feature flag, so people can enable it when they want.
• Add docs about this new functionality to utoipa-gen/src/lib.rs and list the new feature also in README.md and in utoipa/src/lib.rs

You can generate the doc with, and then use browser to see the output.

cargo doc --workspace --no-deps --features utoipa/json,utoipa/actix_extras,utoipa/openapi_extensions

[juhaku]

🏆 pretty good, let's get it merged