gotham-restful

This crate is an extension to the popular gotham web framework for Rust. It allows you to create resources with assigned endpoints that aim to be a more convenient way of creating handlers for requests.

Features

• Automatically parse JSON request and produce response bodies
• Allow using raw request and response bodies
• Convenient macros to create responses that can be registered with gotham’s router
• Auto-Generate an OpenAPI specification for your API
• Manage CORS headers so you don’t have to
• Manage Authentication with JWT
• Integrate diesel connection pools for easy database integration

Safety

This crate is just as safe as you’d expect from anything written in safe Rust - and #![forbid(unsafe_code)] ensures that no unsafe was used.

Endpoints

There are a set of pre-defined endpoints that should cover the majority of REST APIs. However, it is also possible to define your own endpoints.

Pre-defined Endpoints

Assuming you assign /foobar to your resource, the following pre-defined endpoints exist:

Each of those endpoints has a macro that creates the neccessary boilerplate for the Resource. A simple example looks like this:

/// Our RESTful resource.
#[derive(Resource)]
#[resource(read)]
struct FooResource;

/// The return type of the foo read endpoint.
#[derive(Serialize)]
struct Foo {
	id: u64
}

/// The foo read endpoint.
#[read]
fn read(id: u64) -> Success<Foo> {
	Foo { id }.into()
}

Custom Endpoints

Defining custom endpoints is done with the #[endpoint] macro. The syntax is similar to that of the pre-defined endpoints, but you need to give it more context:

use gotham_restful::gotham::hyper::Method;

#[derive(Resource)]
#[resource(custom_endpoint)]
struct CustomResource;

/// This type is used to parse path parameters.
#[derive(Clone, Deserialize, StateData, StaticResponseExtender)]
struct CustomPath {
	name: String
}

#[endpoint(
	uri = "custom/:name/read",
	method = "Method::GET",
	params = false,
	body = false
)]
fn custom_endpoint(path: CustomPath) -> Success<String> {
	path.name.into()
}

Arguments

Some endpoints require arguments. Those should be

• id Should be a deserializable json-primitive like i64 or String.
• body Should be any deserializable object, or any type implementing RequestBody.
• query Should be any deserializable object whose variables are json-primitives. It will however not be parsed from json, but from HTTP GET parameters like in search?id=1. The type needs to implement QueryStringExtractor.

Additionally, all handlers may take a reference to gotham’s State. Please note that for async handlers, it needs to be a mutable reference until rustc’s lifetime checks across await bounds improve.

Uploads and Downloads

By default, every request body is parsed from json, and every respone is converted to json using serde_json. However, you may also use raw bodies. This is an example where the request body is simply returned as the response again, no json parsing involved:

#[derive(Resource)]
#[resource(create)]
struct ImageResource;

#[derive(FromBody, RequestBody)]
#[supported_types(mime::IMAGE_GIF, mime::IMAGE_JPEG, mime::IMAGE_PNG)]
struct RawImage {
	content: Vec<u8>,
	content_type: Mime
}

#[create]
fn create(body: RawImage) -> Raw<Vec<u8>> {
	Raw::new(body.content, body.content_type)
}

Custom HTTP Headers

You can read request headers from the state as you would in any other gotham handler, and specify custom response headers using Response::header.

#[derive(Resource)]
#[resource(read_all)]
struct FooResource;

#[read_all]
async fn read_all(state: &mut State) -> NoContent {
	let headers: &HeaderMap = state.borrow();
	let accept = &headers[ACCEPT];

	let mut res = NoContent::default();
	res.header(VARY, "accept".parse().unwrap());
	res
}

Features

To make life easier for common use-cases, this create offers a few features that might be helpful when you implement your web server. The complete feature list is

• auth Advanced JWT middleware
• cors CORS handling for all endpoint handlers
• database diesel middleware support
• errorlog log errors returned from endpoint handlers
• full enables all features except without-openapi
• openapi router additions to generate an openapi spec
• without-openapi (default) disables openapi support.

Authentication Feature

In order to enable authentication support, enable the auth feature gate. This allows you to register a middleware that can automatically check for the existence of an JWT authentication token. Besides being supported by the endpoint macros, it supports to lookup the required JWT secret with the JWT data, hence you can use several JWT secrets and decide on the fly which secret to use. None of this is currently supported by gotham’s own JWT middleware.

A simple example that uses only a single secret looks like this:

#[derive(Resource)]
#[resource(read)]
struct SecretResource;

#[derive(Serialize)]
struct Secret {
	id: u64,
	intended_for: String
}

#[derive(Deserialize, Clone)]
struct AuthData {
	sub: String,
	exp: u64
}

#[read]
fn read(auth: AuthStatus<AuthData>, id: u64) -> AuthSuccess<Secret> {
	let intended_for = auth.ok()?.sub;
	Ok(Secret { id, intended_for })
}

fn main() {
	let auth: AuthMiddleware<AuthData, _> = AuthMiddleware::new(
		AuthSource::AuthorizationHeader,
		AuthValidation::default(),
		StaticAuthHandler::from_array(b"zlBsA2QXnkmpe0QTh8uCvtAEa4j33YAc")
	);
	let (chain, pipelines) = single_pipeline(new_pipeline().add(auth).build());
	gotham::start(
		"127.0.0.1:8080",
		build_router(chain, pipelines, |route| {
			route.resource::<SecretResource>("secret");
		})
	)
	.expect("Failed to start gotham");
}

CORS Feature

The cors feature allows an easy usage of this web server from other origins. By default, only the Access-Control-Allow-Methods header is touched. To change the behaviour, add your desired configuration as a middleware.

A simple example that allows authentication from every origin (note that * always disallows authentication), and every content type, looks like this:

#[derive(Resource)]
#[resource(read_all)]
struct FooResource;

#[read_all]
fn read_all() {
	// your handler
}

fn main() {
	let cors = CorsConfig {
		origin: Origin::Copy,
		headers: Headers::List(vec![CONTENT_TYPE]),
		max_age: 0,
		credentials: true
	};
	let (chain, pipelines) = single_pipeline(new_pipeline().add(cors).build());
	gotham::start(
		"127.0.0.1:8080",
		build_router(chain, pipelines, |route| {
			route.resource::<FooResource>("foo");
		})
	)
	.expect("Failed to start gotham");
}

The cors feature can also be used for non-resource handlers. Take a look at CorsRoute for an example.

Database Feature

The database feature allows an easy integration of diesel into your handler functions. Please note however that due to the way gotham’s diesel middleware implementation, it is not possible to run async code while holding a database connection. If you need to combine async and database, you’ll need to borrow the connection from the State yourself and return a boxed future.

A simple non-async example looks like this:

#[derive(Resource)]
#[resource(read_all)]
struct FooResource;

#[derive(Queryable, Serialize)]
struct Foo {
	id: i64,
	value: String
}

#[read_all]
fn read_all(conn: &mut PgConnection) -> QueryResult<Vec<Foo>> {
	foo::table.load(conn)
}

type Repo = gotham_middleware_diesel::Repo<PgConnection>;

fn main() {
	let repo = Repo::new(&env::var("DATABASE_URL").unwrap());
	let diesel = DieselMiddleware::new(repo);

	let (chain, pipelines) = single_pipeline(new_pipeline().add(diesel).build());
	gotham::start(
		"127.0.0.1:8080",
		build_router(chain, pipelines, |route| {
			route.resource::<FooResource>("foo");
		})
	)
	.expect("Failed to start gotham");
}

OpenAPI Feature

The OpenAPI feature is probably the most powerful one of this crate. Definitely read this section carefully both as a binary as well as a library author to avoid unwanted suprises.

In order to automatically create an openapi specification, gotham-restful needs knowledge over all routes and the types returned. serde does a great job at serialization but doesn’t give enough type information, so all types used in the router need to implement OpenapiType. This can be derived for almoust any type and there should be no need to implement it manually. A simple example looks like this:

#[derive(Resource)]
#[resource(read_all)]
struct FooResource;

#[derive(OpenapiType, Serialize)]
struct Foo {
	bar: String
}

#[read_all]
fn read_all() -> Success<Foo> {
	Foo {
		bar: "Hello World".to_owned()
	}
	.into()
}

fn main() {
	gotham::start(
		"127.0.0.1:8080",
		build_simple_router(|route| {
			let info = OpenapiInfo {
				title: "My Foo API".to_owned(),
				version: "0.1.0".to_owned(),
				urls: vec!["https://example.org/foo/api/v1".to_owned()]
			};
			route.with_openapi(info, |mut route| {
				route.resource::<FooResource>("foo");
				route.openapi_spec("openapi");
				route.openapi_doc("/");
			});
		})
	)
	.expect("Failed to start gotham");
}

Above example adds the resource as before, but adds two other endpoints as well: /openapi and /. The first one will return the generated openapi specification in JSON format, allowing you to easily generate clients in different languages without worying to exactly replicate your api in each of those languages. The second one will return documentation in HTML format, so you can easily view your api and share it with other people.

Gotchas

The openapi feature has some gotchas you should be aware of.

• The name of a struct is used as a “link” in the openapi specification. Therefore, if you have two structs with the same name in your project, the openapi specification will be invalid as only one of the two will make it into the spec.

• By default, the without-openapi feature of this crate is enabled. Disabling it in favour of the openapi feature will add additional type bounds and method requirements to some of the traits and types in this crate, for example instead of Endpoint you now have to implement EndpointWithSchema. This means that some code might only compile on either feature, but not on both. If you are writing a library that uses gotham-restful, it is strongly recommended to pass both features through and conditionally enable the openapi code, like this:

  #[derive(Deserialize, Serialize)]
  #[cfg_attr(feature = "openapi", derive(openapi_type::OpenapiType))]
  struct Foo;
  

Versioning

Like all rust crates, this crate will follow semantic versioning guidelines. However, changing the MSRV (minimum supported rust version) is not considered a breaking change.

License

Copyright (C) 2019-2024 Dominic Meiser and contributors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

	https://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.