A path parameter definition with explicit serialization settings.

Tesla.OpenAPI.PathParam is a value object for path parameter metadata whose serialization needs to be controlled explicitly. Its serialization options follow the OpenAPI path parameter style semantics.

In Tesla.Middleware.PathParams :modern mode, define path parameters once and pass them through Tesla.Env.private/0 with Tesla.OpenAPI.PathParams:

path_params = Tesla.OpenAPI.PathParams.new!([PathParam.new!("id")])
private = Tesla.OpenAPI.PathParams.put_private(path_params)

Tesla.get(client, "/items/{id}",
  opts: [path_params: %{"id" => 42}],
  private: private
)

Pass options when a value needs non-default path serialization:

alias Tesla.OpenAPI.PathParam

Tesla.OpenAPI.PathParams.new!([
  PathParam.new!("coords", style: :matrix, explode: true)
])

Encoding

Tesla.Middleware.PathParams serializes values using the OpenAPI path parameter rules for the simple, matrix, and label styles. Serialized values are percent-encoded against the RFC 3986 unreserved set (A-Z, a-z, 0-9, -, _, ., ~); spaces become %20 (not +).

With allow_reserved: true, path-safe reserved characters are preserved, but characters that would change the URL path shape, such as /, ?, or #, are still percent-encoded.

Object Value Ordering

Object values may be passed as maps, structs, or keyword lists. Keyword lists preserve insertion order; map iteration order is intrinsic and not guaranteed across Elixir versions. Pass an ordered keyword list when the exact serialized order matters.

Missing And Empty Values

nil values and missing path parameters are handled by Tesla.Middleware.PathParams, which leaves unmatched placeholders untouched. Empty arrays and empty objects serialize according to the OpenAPI "undefined" column for the selected style.