tonic-types

A collection of useful protobuf types that can be used with tonic.

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.

Usage

Useful protobuf types are available through the [pb] module. They can be imported and worked with directly.

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.

Getting Started

toml [dependencies] tonic = <tonic-version> tonic-types = <tonic-types-version>

Examples

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.

Server Side: Generating [tonic::Status] with an [ErrorDetails] struct

```rust use tonic::{Code, Status}; use tonic_types::{ErrorDetails, StatusExt};

// ... // Inside a gRPC server endpoint that returns Result<Response<T>, Status>

// Create empty ErrorDetails struct let mut err_details = ErrorDetails::new();

// Add error details conditionally if somecondition { errdetails.addbadrequestviolation( "fielda", "description of why the field_a is invalid" ); }

if othercondition { errdetails.addbadrequestviolation( "fieldb", "description of why the field_b is invalid", ); }

// Check if any error details were set and return error status if so if errdetails.hasbadrequestviolations() { // Add additional error details if necessary errdetails .addhelplink("description of link", "https://resource.example.local") .setlocalized_message("en-US", "message for the user");

let status = Status::with_error_details(
    Code::InvalidArgument,
    "bad request",
    err_details,
);
return Err(status);

}

// Handle valid request // ... ```

Client Side: Extracting an [ErrorDetails] struct from [tonic::Status]

```rust use tonic::{Response, Status}; use tonic_types::StatusExt;

// ... // Where req_result was returned by a gRPC client endpoint method fn handlerequestresult(reqresult: Result, Status>) { match reqresult { Ok(response) => { // Handle successful response }, Err(status) => { let errdetails = status.geterrordetails(); if let Some(badrequest) = errdetails.badrequest() { // Handle badrequest details } if let Some(help) = errdetails.help() { // Handle help details } if let Some(localizedmessage) = errdetails.localizedmessage() { // Handle localizedmessage details } } }; } ```

Working with different error message types

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].

Alternative tonic::Status associated functions and methods

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.

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].