Falco.OpenAPI

open Falco
open Falco.OpenApi
open Falco.Routing

let endpoints =
    [
        get "/" (Response.ofPlainText "Hello World!")
            |> OpenApi.name "HelloWorld"
            |> OpenApi.summary "This is a summary"
            |> OpenApi.description "This is a test description, which is the long form of the summary."
            |> OpenApi.returnType typeof<string>
    ]

Falco.OpenAPI is a library for generating OpenAPI documentation for Falco applications. It provides a set of combinators for annotating Falco routes with OpenAPI metadata, which can be used to generate OpenAPI documentation.

Key Features

• Generates OpenAPI 3.0 documentation.
• Provides a set of combinators for annotating Falco routes with OpenAPI metadata.
• Generates OpenAPI documentation from metadata associated to Falco routes.
• Allows for customization of the generated OpenAPI documentation.

Design Goals

• Minimalistic and easy to use.
• Explicit, allowing for fine-grained control over the generated OpenAPI documentation.
• Type-safe and to leverage the type system to prevent common mistakes.
• Composable, allowing for the generation of complex OpenAPI documentation.

Getting Started

This guide assumes you have a Falco project setup. If you don't, you can create a new Falco project using the following command:

> dotnet new web -lang F# -o HelloWorld
> cd HelloWorldApp

Install the nuget package:

> dotnet add package Falco
> dotnet add package Falco.OpenApi

Remove any *.fs files created automatically, create a new file named Program.fs and set the contents to the following:

open Falco
open Falco.Routing
open Microsoft.AspNetCore.Builder

let bldr = WebApplication.CreateBuilder()
let wapp = bldr.Build()

let endpoints =
    [
        get "/" (Response.ofPlainText "Hello World!")
    ]

wapp.UseFalco(endpoints)
    .Run()

Now, let's incorporate OpenAPI documentation into our Falco application. Update the Program.fs file to the following:

// ..

let endpoints =
    [
        get "/" (Response.ofPlainText "Hello World!")
            |> OpenApi.name "HelloWorld"
            |> OpenApi.summary "This is a summary"
            |> OpenApi.description "This is a test description, which is the long form of the summary."
            |> OpenApi.returnType typeof<string>
    ]

// ..

Which produces the following OpenAPI documentation:

{
  "openapi": "3.0.1",
  "info": {
    "title": "HelloWorld",
    "version": "1.0"
  },
  "paths": {
    "/": {
      "get": {
        "tags": [
          "HelloWorld"
        ],
        "summary": "This is a summary",
        "description": "This is a test description, which is the long form of the summary",
        "operationId": "HelloWorld",
        "responses": {
          "200": {
            "description": "OK",
            "content": {
              "text/plain": {
                "schema": {
                  "type": "string"
                }
              }
            }
          }
        }
      }
    }
  },
  "components": { }
}

Specs

Name (Operation ID)

open Falco
open Falco.OpenApi
open Falco.Routing

let endpoints =
    [
        get "/" (Response.ofPlainText "Hello World!")
            |> OpenApi.name "HelloWorld"
    ]

Summary

open Falco
open Falco.OpenApi
open Falco.Routing

let endpoints =
    [
        get "/" (Response.ofPlainText "Hello World!")
            |> OpenApi.summary "This is a summary"
    ]

Description

open Falco
open Falco.OpenApi
open Falco.Routing

let endpoints =
    [
        get "/" (Response.ofPlainText "Hello World!")
            |> OpenApi.description "This is a description"
    ]

Return Type

open Falco
open Falco.OpenApi
open Falco.Routing

let endpoints =
    [
        get "/" (Response.ofPlainText "Hello World!")
            |> OpenApi.returns typeof<string>
            // or,
            // |> OpenApi.returns { Return = typeof<string>; ContentType = ["text/plain"]; Status = 200 }
    ]

Route Parameters

open Falco
open Falco.OpenApi
open Falco.Routing

let endpoints =
    [
        mapGet "/hello/{name?}"
            (fun route -> route?name.AsString("world"))
            Response.ofPlainText
            |> OpenApi.route [
                { Type = typeof<string>; Name = "name"; Required = false } ]
    ]

Query Parameters

open Falco
open Falco.OpenApi
open Falco.Routing

let endpoints =
    [
        mapGet "/hello"
            (fun route ->
                let age = route?age.AsInt(0)
                $"Hello there, your are {age} years old.")
            Response.ofPlainText
            |> OpenApi.route [
                { Type = typeof<int>; Name = "age"; Required = false } ]
    ]

Tags

open Falco
open Falco.OpenApi
open Falco.Routing

let endpoints =
    [
        get "/" (Response.ofPlainText "Hello World!")
            |> OpenApi.tags [
                "tag1"
                "tag2" ]
    ]

Find a bug?

There's an issue for that.

License

Built with ♥ by Pim Brouwers in Toronto, ON. Licensed under Apache License 2.0.