gotham-restful

This crate is an extension to the popular gotham web framework for Rust. It allows you to create resources with assigned methods 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.

Methods

Assuming you assign /foobar to your resource, you can implement the following methods:

Method Name	Required Arguments	HTTP Verb	HTTP Path
read_all		GET	/foobar
read	id	GET	/foobar/:id
search	query	GET	/foobar/search
create	body	POST	/foobar
change_all	body	PUT	/foobar
change	id, body	PUT	/foobar/:id
remove_all		DELETE	/foobar
remove	id	DELETE	/foobar/:id

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

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

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

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

Arguments

Some methods 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, non-async handlers may take a reference to gotham's State. If you need to have an async handler (that is, the function that the method macro is invoked on is declared as async fn), consider returning the boxed future instead. Since State does not implement Sync there is unfortunately no more convenient way.

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

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
• chrono openapi support for chrono types
• cors CORS handling for all method handlers
• database diesel middleware support
• errorlog log errors returned from method handlers
• openapi router additions to generate an openapi spec
• uuid openapi support for uuid

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 method 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 could look 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(SecretResource)]
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");
	}));
}

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, could look like this:

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

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

fn main() {
	let cors = CorsConfig {
		origin: Origin::Copy,
		headers: 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");
	}));
}

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 could look like this:

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

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

#[read_all(FooResource)]
fn read_all(conn: &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");
	}));
}

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 could look like this:

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

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

#[read_all(FooResource)]
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.get_openapi("openapi");
		});
	}));
}

Above example adds the resource as before, but adds another endpoint that we specified as /openapi that will return the generated openapi specification. This allows you to easily write clients in different languages without worying to exactly replicate your api in each of those languages.

However, as of right now there is one caveat. If you wrote code before enabling the openapi feature, it is likely to break. This is because of the new requirement of OpenapiType for all types used with resources, even outside of the with_openapi scope. This issue will eventually be resolved. If you are writing a library that uses gotham-restful, make sure that you expose an openapi feature. In other words, put

[features]
openapi = ["gotham-restful/openapi"]

into your libraries Cargo.toml and use the following for all types used with handlers:

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

Examples

There is a lack of good examples, but there is currently a collection of code in the example directory, that might help you. Any help writing more examples is highly appreciated.

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) 2020-2021 Dominic Meiser and contributors.

Licensed under your option of:

• Apache License Version 2.0
• Eclipse Public License Version 2.0