Enum Error 

#[non_exhaustive]
pub enum Error {
    Api(ApiError),
    Transport(TransportError),
    Decode {
        path: String,
        body: String,
        source: Error,
    },
    Credentials(String),
    InvalidRequest(String),
    Stream(String),
    InvalidUrl(String),
    RetriesExhausted {
        attempts: u32,
        last: ApiError,
    },
}

Anything that can go wrong while talking to Alpaca.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Api(ApiError)

Alpaca returned a non-success HTTP status.

Transport(TransportError)

The request never completed: DNS, TLS, connection, or timeout failure.

Decode

A response arrived but could not be deserialized into the expected type.

body carries the raw payload so the mismatch can be diagnosed without re-issuing the request.

Fields

path: String

The request path whose response failed to decode.

body: String

The raw response body, truncated to a reasonable length.

source: Error

The underlying deserialization error.

Credentials(String)

The supplied credentials are structurally invalid.

InvalidRequest(String)

A request was rejected locally, before any network call was made.

Stream(String)

A stream failed: the connection, the handshake, or a frame carried on it.

This covers both stream transports — the msgpack and JSON websockets and the SSE event streams — because the failures are the same shape and a caller matching on them is not usually asking which one broke.

The boundary against InvalidRequest is where the failure happened, not what caused it. Anything the crate determines locally before a socket is opened — an empty subscription set, a non-positive timeout, an unrecognised feed — stays InvalidRequest. Everything that fails on the wire is this.

A stream error is not necessarily the end of the stream. The market data stream reconnects from most of them and stops on the two that never resolve by retrying — a subscription the account is not entitled to, and credentials the server rejects.

InvalidUrl(String)

The configured base URL could not be joined with the request path.

RetriesExhausted

Every retry attempt returned a retryable status.

Carries the final ApiError so the caller still sees what Alpaca said.

Fields

attempts: u32

Total number of requests issued, including the first.

last: ApiError

The error returned by the final attempt.

Implementations

impl Error

pub fn status(&self) -> Option<u16>

The HTTP status code, when the failure came from a response.

pub fn is_transient(&self) -> bool

Whether this failure is transient — worth trying again if the request is safe to repeat.

Named for what it can actually tell you. The obvious reading of a method called is_retryable is “it is safe to send this again”, and that is not something an error alone can answer — which is why it is not called that.

Transient does not mean safe to replay. A timed-out POST /v2/orders and a 504 on the same request are both transient, and both are indistinguishable from an order Alpaca accepted whose response was lost; replaying either places a second order. The one transport failure that is safe is a connect error, because nothing was sent.

The safety question belongs to the request method, and the client answers it internally: GET, PUT and DELETE are replayed, POST and PATCH are not, except on a 429. If you are deciding whether to re-issue a call yourself, that is the rule to apply — this predicate only tells you whether trying again could plausibly work.

Trait Implementations

impl Debug for Error

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

Formats the value using the given formatter.

impl Display for Error

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

Formats the value using the given formatter.

impl Error for Error

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl From<ApiError> for Error

fn from(source: ApiError) -> Self

Converts to this type from the input type.