A helper trait to assist with passing error types through return tonic::Status
messages.
This works with the thiserror crates, but using that is not required. If you
are not using thiserror then at the moment you will need to manually implement
std::fmt::Display for your type. Your error type will also need to derive
serde::{Serialize, Deserialize}.
In order to use this, you will need to #[derive(TonicError)] on your error type.
```rust
pub enum MathsError { #[error("division by zero for inputs: a={0} b={1}")] DivByZero(i32, i32), } ```
The TonicError trait provides two functions that will be able to convert your
type to and from a tonic::Status. fn to_status(&self) -> Status and fn
from_status(s: &'de Status) -> Result<Self, TonicErrorError> - the
TonicErrorError is used to wrap serde and tonic errors, as well as if the
incorrect Status code is set, or the key is not a part of the Status
metadata map.
These examples are taken from the included examples.
rust
async fn div(&self, req: Request<DivRequest>) -> Result<Response<DivResponse>, Status> {
let req = req.into_inner();
if req.b == 0 {
// We invoke `to_status` on our error type.
return Err(MathsError::DivByZero(req.a, req.b).to_status());
}
let result = req.a as f64 / req.b as f64;
Ok(Response::new(DivResponse { result }))
}
``rust
pub async fn div(&mut self, a: i32, b: i32) -> Result<f64, MathsError> {
let req = Request::new(DivRequest { a, b });
let resp = self
.client
.div(req)
.await
// We map thetonic::Status` to our custom error type.
.maperr(|s| TonicError::fromstatus(&s).unwrap())?;
Ok(resp.into_inner().result)
} ```
See the tonic-error-example subdirectory in this repo for a working
client/server example.
This is released under the Apache 2.0 license.