Enum StreamFrame 

pub enum StreamFrame {
    Data(Value),
    Error {
        code: String,
        payload: Value,
    },
}

One frame yielded by a StreamHandler.

Mirrors the SPEC §4.2 SSE event shapes:

• Self::Data → event: data\ndata: <json>\n\n
• Self::Error → event: error\ndata: <{code,payload}>\n\n

The terminal event: end\ndata:\n\n frame is implicit — when the underlying stream finishes, the router emits it. Stream handlers should just stop yielding rather than try to encode the end frame themselves.

StreamFrame is intentionally runtime-only: it carries pre-serialized serde_json::Values so the router can splat them into SSE bodies without re-running user Serialize impls. It does not implement serde::Serialize/Deserialize itself — there’s no wire shape to round trip.

Variants

Data(Value)

A successful payload frame. Becomes event: data\ndata: <json>\n\n on the SSE wire.

Error

An error frame. Becomes event: error\ndata: {"code","payload"}\n\n on the SSE wire. Streaming errors do not terminate the connection at the SPEC level — the user’s stream chooses whether to keep yielding after an Error frame or stop. (The HTTP response is already committed by the time SSE frames flow, so there’s no status code to flip.)

Fields

code: String

Stable error code emitted with the SSE error frame.

payload: Value

Error payload serialized into the SSE error frame.

Implementations

impl StreamFrame

pub fn data(value: impl Serialize) -> Self

Serialize a value into StreamFrame::Data.

On serialization failure, falls back to a StreamFrame::Error with code = "serialization_error" and a null payload — same fallback shape as ProcedureResult::ok, for consistency between the unary and streaming paths.

pub fn err(code: impl Into<String>, payload: impl Serialize) -> Self

Build StreamFrame::Error from a stable code and serializable payload. Same fallback semantics as Self::data when the payload fails to serialize.

pub fn from_taut_error<E: TautError>(e: E) -> Self

Build StreamFrame::Error from a crate::TautError. The payload is serde_json::to_value(&e); if that fails the payload becomes null but code is still taken from the error.

Note that, unlike the unary ProcedureResult::from_taut_error, the http_status of the error is intentionally dropped: SSE frames flow after the HTTP status line is already committed, so per-frame status codes don’t fit. Callers wanting status-mapping semantics should use a unary procedure instead.

Trait Implementations

impl Clone for StreamFrame

fn clone(&self) -> StreamFrame

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for StreamFrame

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.