salvo-path-syntax

name	salvo-path-syntax
description	Path parameter syntax guide for Salvo routing. Explains the `{}` syntax (v0.76+) vs deprecated `<>` syntax, with migration examples.
version	0.94.0
tags	["core","routing","path-syntax","migration"]

Salvo Path Parameter Syntax

Salvo 0.76+ uses curly-brace syntax {...} for path parameters. The old angle-bracket form <...> (pre-0.76) is removed and will not match.

Current syntax (0.76+)

Router::with_path("users/{id}")                 // basic
Router::with_path("users/{id:num}")             // typed (num|i32|i64|u32|u64)
Router::with_path(r"users/{id|\d+}")            // regex
Router::with_path("files/{*}")                  // single-segment wildcard
Router::with_path("files/{*name}")              // named single-segment wildcard
Router::with_path("static/{**path}")            // rest-of-path wildcard

Migration from <> to {}

Before 0.76	0.76+
<id>	{id}
<id:num>	{id:num}
<id|\d+>	{id|\d+}
<*> / <*name>	{*} / {*name}
<**> / <**path>	{**} / {**path}

Mechanical substitution: < to {, > to } in every with_path(...) / path(...) argument. Update any tests asserting on path strings.

BAD (pre-0.76, will not match in current Salvo):

Router::with_path("users/<id>/posts/<**rest>")

GOOD:

Router::with_path("users/{id}/posts/{**rest}")

Parameter types

Router::with_path("users/{id:num}")   // any integer
Router::with_path("users/{id:i32}")   // signed 32-bit
Router::with_path("users/{id:i64}")
Router::with_path("users/{id:u32}")
Router::with_path("users/{id:u64}")

// Regex: characters between `|` and `}` form the pattern
Router::with_path(r"posts/{slug|[a-z0-9-]+}")
Router::with_path(r"users/{id|[0-9a-f-]{36}}")  // UUID

Typed and regex parameters reject non-matching values at the routing layer (returns 404), so handlers can unwrap.

Accessing params

#[handler]
async fn show(req: &mut Request) -> String {
    let id: i64 = req.param("id").unwrap();
    format!("id = {id}")
}

#[handler]
async fn serve(req: &mut Request) -> String {
    let rest: String = req.param("path").unwrap();  // from {**path}
    format!("serving {rest}")
}

req.param::<T>(name) returns Option<T> and deserializes via serde.

Gotchas

• Do not mix syntaxes: "users/{id}/posts/<pid>" will not compile-error but the <pid> segment is treated as a literal.
• Wildcards {**} are greedy and capture trailing slashes — name them for clarity: {**path}.
• {*} matches exactly one segment; {**} matches zero or more. Use {*name} when you need a single non-empty segment.

Related Skills

• salvo-routing: Full routing configuration guide
• salvo-basic-app: Basic application setup