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feat(types): Add gRPC Richer Error Model support (Docs) (#1317)
* types: improve `lib.rs` docs, add `README` file * types: update `Cargo.toml` file
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# tonic-types | ||
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A collection of useful protobuf types that can be used with `tonic`. | ||
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This crate also introduces the [`StatusExt`] trait and implements it in | ||
[`tonic::Status`], allowing the implementation of the [gRPC Richer Error Model] | ||
with [`tonic`] in a convenient way. | ||
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## Usage | ||
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Useful protobuf types are available through the [`pb`] module. They can be | ||
imported and worked with directly. | ||
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The [`StatusExt`] trait adds associated functions to [`tonic::Status`] that can | ||
be used on the server side to create a status with error details, which can then | ||
be returned to gRPC clients. Moreover, the trait also adds methods to | ||
[`tonic::Status`] that can be used by a tonic client to extract error details, | ||
and handle them with ease. | ||
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## Getting Started | ||
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```toml | ||
[dependencies] | ||
tonic = <tonic-version> | ||
tonic-types = <tonic-types-version> | ||
``` | ||
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## Examples | ||
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The examples bellow cover a basic use case of the [gRPC Richer Error Model]. | ||
More complete server and client implementations are provided in the | ||
**Richer Error example**, located in the main repo [examples] directory. | ||
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### Server Side: Generating [`tonic::Status`] with an [`ErrorDetails`] struct | ||
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```rust | ||
use tonic::{Code, Status}; | ||
use tonic_types::{ErrorDetails, StatusExt}; | ||
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// ... | ||
// Inside a gRPC server endpoint that returns `Result<Response<T>, Status>` | ||
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// Create empty `ErrorDetails` struct | ||
let mut err_details = ErrorDetails::new(); | ||
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// Add error details conditionally | ||
if some_condition { | ||
err_details.add_bad_request_violation( | ||
"field_a", | ||
"description of why the field_a is invalid" | ||
); | ||
} | ||
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if other_condition { | ||
err_details.add_bad_request_violation( | ||
"field_b", | ||
"description of why the field_b is invalid", | ||
); | ||
} | ||
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// Check if any error details were set and return error status if so | ||
if err_details.has_bad_request_violations() { | ||
// Add additional error details if necessary | ||
err_details | ||
.add_help_link("description of link", "https://resource.example.local") | ||
.set_localized_message("en-US", "message for the user"); | ||
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let status = Status::with_error_details( | ||
Code::InvalidArgument, | ||
"bad request", | ||
err_details, | ||
); | ||
return Err(status); | ||
} | ||
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// Handle valid request | ||
// ... | ||
``` | ||
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### Client Side: Extracting an [`ErrorDetails`] struct from [`tonic::Status`] | ||
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```rust | ||
use tonic::{Response, Status}; | ||
use tonic_types::StatusExt; | ||
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// ... | ||
// Where `req_result` was returned by a gRPC client endpoint method | ||
fn handle_request_result<T>(req_result: Result<Response<T>, Status>) { | ||
match req_result { | ||
Ok(response) => { | ||
// Handle successful response | ||
}, | ||
Err(status) => { | ||
let err_details = status.get_error_details(); | ||
if let Some(bad_request) = err_details.bad_request() { | ||
// Handle bad_request details | ||
} | ||
if let Some(help) = err_details.help() { | ||
// Handle help details | ||
} | ||
if let Some(localized_message) = err_details.localized_message() { | ||
// Handle localized_message details | ||
} | ||
} | ||
}; | ||
} | ||
``` | ||
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## Working with different error message types | ||
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Multiple examples are provided at the [`ErrorDetails`] doc. Instructions about | ||
how to use the fields of the standard error message types correctly are provided | ||
at [error_details.proto]. | ||
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## Alternative `tonic::Status` associated functions and methods | ||
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In the [`StatusExt`] doc, an alternative way of interacting with | ||
[`tonic::Status`] is presented, using vectors of error details structs wrapped | ||
with the [`ErrorDetail`] enum. This approach can provide more control over the | ||
vector of standard error messages that will be generated or that was received, | ||
if necessary. To see how to adopt this approach, please check the | ||
[`StatusExt::with_error_details_vec`] and [`StatusExt::get_error_details_vec`] | ||
docs, and also the main repo's [Richer Error example] directory. | ||
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Besides that, multiple examples with alternative error details extraction | ||
methods are provided in the [`StatusExt`] doc, which can be specially | ||
useful if only one type of standard error message is being handled by the | ||
client. For example, using [`StatusExt::get_details_bad_request`] is a | ||
more direct way of extracting a [`BadRequest`] error message from | ||
[`tonic::Status`]. | ||
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[`tonic::Status`]: https://docs.rs/tonic/latest/tonic/struct.Status.html | ||
[`tonic`]: https://docs.rs/tonic/latest/tonic/ | ||
[gRPC Richer Error Model]: https://www.grpc.io/docs/guides/error/ | ||
[`pb`]: https://docs.rs/tonic-types/latest/tonic_types/pb/index.html | ||
[`StatusExt`]: https://docs.rs/tonic-types/latest/tonic_types/trait.StatusExt.html | ||
[examples]: https://github.com/hyperium/tonic/tree/master/examples | ||
[`ErrorDetails`]: https://docs.rs/tonic-types/latest/tonic_types/struct.ErrorDetails.html | ||
[error_details.proto]: https://github.com/googleapis/googleapis/blob/master/google/rpc/error_details.proto | ||
[`ErrorDetail`]: https://docs.rs/tonic-types/latest/tonic_types/enum.ErrorDetail.html | ||
[`StatusExt::with_error_details_vec`]: https://docs.rs/tonic-types/latest/tonic_types/trait.StatusExt.html#tymethod.with_error_details_vec | ||
[`StatusExt::get_error_details_vec`]: https://docs.rs/tonic-types/latest/tonic_types/trait.StatusExt.html#tymethod.get_error_details_vec | ||
[Richer Error example]: https://github.com/hyperium/tonic/tree/master/examples/src/richer-error | ||
[`StatusExt::get_details_bad_request`]: https://docs.rs/tonic-types/latest/tonic_types/trait.StatusExt.html#tymethod.get_details_bad_request | ||
[`BadRequest`]: https://docs.rs/tonic-types/latest/tonic_types/struct.BadRequest.html |
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