utoipa - Auto generated OpenAPI documentation

Want to have your API documented with OpenAPI? But you dont want to see the trouble with manual yaml or json tweaking? Would like it to be so easy that it would almost be like utopic? Don't worry utoipa is just there to fill this gap. It aims to do if not all then the most of heavy lifting for you enabling you to focus writing the actual API logic instead of documentation. It aims to be minimal, simple and fast. It uses simple proc macros which you can use to annotate your code to have items documented.

Utoipa crate provides auto generated OpenAPI documentation for Rust REST APIs. It treats code first appoach as a first class citizen and simplifies API documentation by providing simple macros for generating the documentation from your code.

It also contains Rust types of OpenAPI spec allowing you to write the OpenAPI spec only using Rust if auto generation is not your flavor or does not fit your purpose.

Long term goal of the library is to be the place to go when OpenAPI documentation is needed in Rust codebase.

Utoipa is framework agnostic and could be used together with any web framework or even without one. While being portable and standalone one of it's key aspects is simple integration with web frameworks.

Currently utoipa provides simple integration with actix-web framework but is not limited to the actix-web framework. All functionalities are not restricted to any specific framework.

What's up with the word play?

The name comes from words utopic and api where uto is the first three letters of utopic and the ipa is api reversed.

Features

default Default enabled features are json.
json Enables serde_json what allow to use json values in OpenAPI specification values. Thus is enabled by default.
actix_extras Enhances actix-web intgration with being able to parse some documentation from actix web macro attributes and types. See the path attribute macro for more details.
debug Add extra traits such as debug traits to openapi definitions and elsewhere.

Install

Add minimal dependency declaration to Cargo.toml.

[dependencies]
utoipa = "0.1.0-rc1"

To enable more features such as use actix framework extras you could define the dependency as follows.

[dependencies]
utoipa = { version = "0.1.0-rc1", features = ["actix_extras"] }

Note! To use utoipa together with Swagger UI you can use the utoipa-swagger-ui crate.

Current project status

Finally in rc the API is fairly stable and most of the features are implemented and documented. While changes might still occur before the final stable release there should not be any more massive changes. The expected changes include mainly performance optimisations and fixing inconsistencies or other minor tweaks and missing features might be included.

The stable release is expected in short future.

Use with cauntion!

See https://github.com/juhaku/utoipa/projects for more details about the progress of the project implementation.

Examples

Create a struct or it could be an enum also. Add Component derive macro to it so it can be registered as a component in OpenApi schema.

use utoipa::Component;

#[derive(Component)]
struct Pet {
   id: u64,
   name: String,
   age: Option<i32>,
}

Create a handler that would handle your business logic and add path proc attribute macro over it.

mod pet_api {
    /// Get pet by id
    ///
    /// Get pet from database by pet id  
    #[utoipa::path(
        get,
        path = "/pets/{id}",
        responses(
            (status = 200, description = "Pet found succesfully", body = Pet),
            (status = 404, description = "Pet was not found")
        ),
        params(
            ("id" = u64, path, description = "Pet database id to get Pet for"),
        )
    )]
    async fn get_pet_by_id(pet_id: u64) -> Pet {
        Pet {
            id: pet_id,
            age: None,
            name: "lightning".to_string(),
        }
    }
}

Tie the Component and the endpoint above to the OpenApi schema with following OpenApi derive proc macro.

use utoipa::OpenApi;

#[derive(OpenApi)]
#[openapi(handlers(pet_api::get_pet_by_id), components(Pet))]
struct ApiDoc;

println!("{}", ApiDoc::openapi().to_pretty_json().unwrap());

This would produce api doc something similar to:

{
  "openapi": "3.0.3",
  "info": {
    "title": "application name from Cargo.toml",
    "description": "description from Cargo.toml",
    "contact": {
      "name": "author name from Cargo.toml",
      "email":"author email from Cargo.toml"
    },
    "license": {
      "name": "license from Cargo.toml"
    },
    "version": "version from Cargo.toml"
  },
  "paths": {
    "/pets/{id}": {
      "get": {
        "tags": [
          "pet_api"
        ],
        "summary": "Get pet by id",
        "description": "Get pet by id\n\nGet pet from database by pet id\n",
        "operationId": "get_pet_by_id",
        "parameters": [
          {
            "name": "id",
            "in": "path",
            "description": "Pet database id to get Pet for",
            "required": true,
            "deprecated": false,
            "schema": {
              "type": "integer",
              "format": "int64"
            }
          }
        ],
        "responses": {
          "200": {
            "description": "Pet found succesfully",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Pet"
                }
              }
            }
          },
          "404": {
            "description": "Pet was not found"
          }
        },
        "deprecated": false
      }
    }
  },
  "components": {
    "schemas": {
      "Pet": {
        "type": "object",
        "required": [
          "id",
          "name"
        ],
        "properties": {
          "id": {
            "type": "integer",
            "format": "int64"
          },
          "name": {
            "type": "string"
          },
          "age": {
            "type": "integer",
            "format": "int32"
          }
        }
      }
    }
  }
}

Go beyond the surface

See how to serve OpenAPI doc via Swagger UI check utoipa-swagger-ui crate for more details.
Browse to examples for more comprehensinve examples.
Modify generated OpenAPI at runtime check Modify trait for more details.
More about OpenAPI security in security documentation.

License

Licensed under either of Apache 2.0 or MIT license at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this crate by you, shall be dual licensed, without any additional terms or conditions.

utoipa 0.1.0-rc1