Struct Error 

pub struct Error { /* private fields */ }

The primary error type for the modo framework.

Error carries:

• an HTTP StatusCode that will be used as the response status,
• a human-readable message string,
• an optional structured details payload (arbitrary JSON),
• an optional boxed source error for causal chaining,
• an optional static error_code string that survives the response pipeline,
• a lagged flag used by the SSE broadcaster to signal that a subscriber dropped messages.

Conversion to HTTP response

Calling into_response() produces a JSON body:

{ "error": { "status": 404, "message": "user not found" } }

If with_details was called, a "details" field is included. A copy of the error (without source) is also stored in response extensions so middleware can inspect it after the fact.

Clone behaviour

Cloning an Error drops the source field because Box<dyn Error> is not Clone. The error_code, details, and all other fields are preserved.

Implementations

impl Error

pub fn new(status: StatusCode, message: impl Into<String>) -> Self

Create a new error with the given HTTP status code and message.

pub fn with_source( status: StatusCode, message: impl Into<String>, source: impl Error + Send + Sync + 'static, ) -> Self

Create a new error with a status code, message, and a boxed source error.

Use chain instead when constructing errors with the builder pattern.

pub fn status(&self) -> StatusCode

Returns the HTTP status code of this error.

pub fn message(&self) -> &str

Returns the human-readable error message.

pub fn details(&self) -> Option<&Value>

Returns the optional structured details payload.

pub fn with_details(self, details: Value) -> Self

Attach a structured JSON details payload (builder-style).

pub fn chain(self, source: impl Error + Send + Sync + 'static) -> Self

Attach a source error (builder-style).

pub fn with_code(self, code: &'static str) -> Self

Attach a static error code to preserve error identity through the response pipeline.

The error code is included in the copy stored in response extensions and can be retrieved after into_response() via Error::error_code.

pub fn error_code(&self) -> Option<&str>

Returns the error code, if one was set.

pub fn source_as<T: Error + 'static>(&self) -> Option<&T>

Downcast the source error to a concrete type.

Returns None if no source is set or if the source is not of type T.

pub fn bad_request(msg: impl Into<String>) -> Self

Create a 400 Bad Request error.

pub fn unauthorized(msg: impl Into<String>) -> Self

Create a 401 Unauthorized error.

pub fn forbidden(msg: impl Into<String>) -> Self

Create a 403 Forbidden error.

pub fn not_found(msg: impl Into<String>) -> Self

Create a 404 Not Found error.

pub fn conflict(msg: impl Into<String>) -> Self

Create a 409 Conflict error.

pub fn payload_too_large(msg: impl Into<String>) -> Self

Create a 413 Payload Too Large error.

pub fn unprocessable_entity(msg: impl Into<String>) -> Self

Create a 422 Unprocessable Entity error.

pub fn too_many_requests(msg: impl Into<String>) -> Self

Create a 429 Too Many Requests error.

pub fn internal(msg: impl Into<String>) -> Self

Create a 500 Internal Server Error.

pub fn bad_gateway(msg: impl Into<String>) -> Self

Create a 502 Bad Gateway error.

pub fn gateway_timeout(msg: impl Into<String>) -> Self

Create a 504 Gateway Timeout error.

pub fn lagged(skipped: u64) -> Self

Create an error indicating a broadcast subscriber lagged behind.

The resulting error has a 500 Internal Server Error status and is_lagged returns true. skipped is the number of messages that were dropped.

pub fn is_lagged(&self) -> bool

Returns true if this error represents a broadcast lag.

Trait Implementations

impl Clone for Error

Clones the error, dropping the source field (which is not Clone).

All other fields — status, message, error_code, details, and lagged — are preserved.

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

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, f: &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<Error> for Error

Converts a std::io::Error into a 500 Internal Server Error.

fn from(err: Error) -> Self

Converts to this type from the input type.

impl From<Error> for Error

Converts a serde_json::Error into a 400 Bad Request.

fn from(err: Error) -> Self

Converts to this type from the input type.

impl From<Error> for Error

Converts a serde_yaml_ng::Error into a 500 Internal Server Error.

fn from(err: Error) -> Self

Converts to this type from the input type.

impl From<Error> for Error

Converts libsql::Error into modo::Error with appropriate HTTP status codes:

• Unique/primary-key constraint violations become 409 Conflict.
• Foreign-key violations become 400 Bad Request.
• QueryReturnedNoRows becomes 404 Not Found.
• Everything else becomes 500 Internal Server Error.

fn from(err: Error) -> Self

Converts to this type from the input type.

impl From<HttpError> for Error

Converts an HttpError into an Error using its canonical status code and message.

fn from(http_err: HttpError) -> Self

Converts to this type from the input type.

impl From<QrError> for Error

fn from(err: QrError) -> Self

Converts to this type from the input type.

impl From<ValidationError> for Error

fn from(ve: ValidationError) -> Self

Converts to this type from the input type.

impl IntoResponse for Error

Converts Error into an axum Response.

Produces a JSON body of the form:

{ "error": { "status": 422, "message": "validation failed" } }

If with_details was called, a "details" key is added under "error".

A copy of the error (without the source field) is stored in response extensions under the type Error so that downstream middleware can inspect it.

fn into_response(self) -> Response

Create a response.