GettingStarted

The OpenAPI.NET library is a document object model (DOM) for an OpenAPI description document. It provides a set of classes for constructing semantically valid descriptions of HTTP APIs. The library also includes a writer for serializing the DOM into JSON or YAML in either OpenAPI v3 or V2 format.

Creating an OpenAPI Document

var document = new OpenApiDocument
{
    Info = new OpenApiInfo
    {
        Version = "1.0.0",
        Title = "Swagger Petstore (Simple)",
    },
    Servers = new List<OpenApiServer>
    {
        new OpenApiServer { Url = "http://petstore.swagger.io/api" }
    },
    Paths = new OpenApiPaths
    {
        ["/pets"] = new OpenApiPathItem
        {
            Operations = new Dictionary<OperationType, OpenApiOperation>
            {
                [OperationType.Get] = new OpenApiOperation
                {
                    Description = "Returns all pets from the system that the user has access to",
                    Responses = new OpenApiResponses
                    {
                        ["200"] = new OpenApiResponse
                        {
                            Description = "OK"
                        }
                    }
                }
            }
        }
    }
};

Reading and writing a OpenAPI description

// using Microsoft.OpenApi.Extensions; // Required for the .Serialize method

var httpClient = new HttpClient
{
    BaseAddress = new Uri("https://raw.githubusercontent.com/OAI/OpenAPI-Specification/")
};

var stream = await httpClient.GetStreamAsync("master/examples/v3.0/petstore.yaml");

// Read V3 as YAML
var openApiDocument = new OpenApiStreamReader().Read(stream, out var diagnostic);

// Write V2 as JSON
var outputString = openApiDocument.Serialize(OpenApiSpecVersion.OpenApi2_0, OpenApiFormat.Json);