Struct TypedErr 

pub struct TypedErr<E> { /* private fields */ }

A typed wrapper around a user error that provides Deref access to the inner error type.

This struct holds an Arc<anyhow::Error> internally and provides safe access to the downcasted error reference. The Arc ensures the error remains valid for the lifetime of this wrapper.

Example

use std::fmt;

use query_flow::{query, Db, QueryError, QueryResultExt, QueryRuntime};

#[derive(Debug)]
struct MyError {
    code: u32,
}

impl fmt::Display for MyError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "my error {}", self.code)
    }
}

impl std::error::Error for MyError {}

#[query]
fn failing(db: &impl Db) -> Result<i32, QueryError> {
    let _ = db;
    Err(MyError { code: 42 }.into())
}

#[query]
fn caller(db: &impl Db) -> Result<String, QueryError> {
    let result = db.query(Failing::new()).downcast_err::<MyError>()?;
    Ok(match result {
        Ok(value) => format!("success: {}", value),
        Err(typed_err) => {
            // typed_err derefs to &MyError
            format!("Error code: {}", typed_err.code)
        }
    })
}

let runtime = QueryRuntime::new();
assert_eq!(*runtime.query(Caller::new()).unwrap(), "Error code: 42");

Implementations

impl<E: Error + Send + Sync + 'static> TypedErr<E>

pub fn get(&self) -> &E

Returns a reference to the inner error.

Trait Implementations

impl<E: Clone> Clone for TypedErr<E>

fn clone(&self) -> TypedErr<E>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<E: Error + Send + Sync + 'static> Debug for TypedErr<E>

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

Formats the value using the given formatter.

impl<E: Error + Send + Sync + 'static> Deref for TypedErr<E>

type Target = E

The resulting type after dereferencing.

fn deref(&self) -> &E

Dereferences the value.

impl<E: Error + Send + Sync + 'static> Display for TypedErr<E>

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

Formats the value using the given formatter.

impl<E> From<TypedErr<E>> for QueryError

fn from(err: TypedErr<E>) -> Self

Converts to this type from the input type.