Tagged enum in Query

[FintanH]

Hey 👋

We're working on creating a query parameter struct but one of the fields is (de)serialized as a tagged enum. So the code roughly looks like the following:

#[serde(rename_all = "camelCase")]
pub struct CobsQuery {
    pub page: Option<usize>,
    pub per_page: Option<usize>,
    pub state: Option<State>,
}

#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, PartialOrd, Ord, Deserialize, Serialize)]
#[serde(rename_all = "camelCase", tag = "status")]
pub enum State {
    #[default]
    Open,
    Draft,
    Archived,
    Merged,
}

We would hope to use the params like: ?page=1?perPage=10?state=open, however, due to the status tag, it would expect state={"status": "open"}.

We can change pub state: Option<State> to pub state: Option<String> and do the parsing of the string instead, but thought we'd first check if it's possible to use the tagged enum approach somehow.

Thanks for any help you can provide! 😊

[davidpdrsn]

Axum uses serde_urlencoded which I believe is limited in this regard. Try searching for issues in their repo.

[FintanH]

Thanks, that's helpful!

[FintanH]

If anyone else is looking, I came across this issue nox/serde_urlencoded#26

Going off the helpful comment here, it's possible to use #[serde(deserialize_with = "path")] on the field and write a different deserializer for the query params :)