Path extractor Vec<String> deserialization support for wildcard paths #3621

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1. jplatte commented on Jan 15, 2026

   

   jplatte

   on Jan 15, 2026

   Contributor

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   To be clear, you're looking for something like this to work, right?

   #[derive(Deserialize)]
   struct PathParams {
       bucket: String,
       key: Vec<String>,
   }
   
   fn get_key_from_bucket(
       Path(params): Path<PathParams>,
       // other extractors
   ) -> impl IntoResponse {
       // handler implementation
   }
   
   router.route("/{bucket}/{*key}", get(get_key_from_bucket));

   I verified that this does not work currently, and I agree that it should. Could take me a while to implement though, I've got a lot of stuff on my plate and the path deserialization code is unfortunately not simple, and not well-commented either.
2. TristanWasTaken commented on Jan 16, 2026

   

   TristanWasTaken

   on Jan 16, 2026

   Last edited by TristanWasTaken

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   @jplatte yes.
   Or from the docs example (https://docs.rs/axum/latest/axum/routing/struct.Router.html#method.route):

   use axum::{
       Router,
       routing::get,
       extract::Path,
   };
   
   let app: Router = Router::new().route("/{*key}", get(handler));
   
   async fn handler(Path(path): Path<Vec<String>>) -> String {
       path
   }

   I'm not familiar with axum's source code so I'm unsure if the path extractor has code at more locations than axum\src\extract\path.

   From what I see, it uses the serde PathDeserializer to parse the route segments and then the serde ValueDeserializer to extract the values.
   Wildcard segments are greedily matched and then forwarded to ValueDeserializer as a string. So I think it is enough to implement serde's deserialize_seq to support Vec<T>?

   I already wrote a prototype that should(?) work. I just kind of got stuck at trying to reuse ValueDeserializer and got into a fight with the borrow checker over lifetimes 😅
   I'll try again this Saturday with owned types and a WildcardValueDeserializer that uses Vec<PercentDecodedStr> instead of &'de PercentDecodedStr.
3. jplatte commented on Jan 16, 2026

   

   jplatte

   on Jan 16, 2026

   Contributor

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   Oh, that doesn't work either? I was sure it does, but can't immediately find any tests for it.

   Feel free to post a draft PR even if you can't actually get it to compile. Happy to help.

   👍React with 👍1Reacted by Tristan
4. quentinLeDilavrec

   added 2 commits that reference this issue on Aug 20, 2026

   parse TrackingAtPathParam.path earlier

   ...

   3b12bd7

   parse TrackingAtPathParam.path earlier

   ...

   38d49a7
5. mladedav

   added this to the 0.9 milestone on Sep 7, 2026