Generate an openapi spec dynamically based on the types used to handle request and response.

It works with any router, it is simple to add support to your router implementing the apirouter interface.

The routers supported out of the box are:

• gorilla-mux
• fiber
• echo

This lib uses kin-openapi to automatically generate and serve a swagger file.

To convert struct to schemas, we use jsonschema library.
The struct must contains the appropriate struct tags to be inserted in json schema to generate the schema dynamically.
It is always possible to add a totally custom swagger schema using kin-openapi.

Install

To use it, install with

go get github.com/davidebianchi/gswagger

Usage

An example usage of this lib with gorilla mux:

context := context.Background()
muxRouter := mux.NewRouter()

router, _ := swagger.NewRouter(gorilla.NewRouter(muxRouter), swagger.Options{
  Context: context,
  Openapi: &openapi3.T{
    Info: &openapi3.Info{
      Title:   "my title",
      Version: "1.0.0",
    },
  },
})

okHandler := func(w http.ResponseWriter, req *http.Request) {
  w.WriteHeader(http.StatusOK)
  w.Write([]byte("OK"))
}

type User struct {
  Name        string   `json:"name" jsonschema:"title=The user name,required" jsonschema_extras:"example=Jane"`
  PhoneNumber int      `json:"phone" jsonschema:"title=mobile number of user"`
  Groups      []string `json:"groups,omitempty" jsonschema:"title=groups of the user,default=users"`
  Address     string   `json:"address" jsonschema:"title=user address"`
}
type errorResponse struct {
  Message string `json:"message"`
}

router.AddRoute(http.MethodPost, "/users", okHandler, swagger.Definitions{
  RequestBody: &swagger.ContentValue{
    Content: swagger.Content{
      "application/json": {Value: User{}},
    },
  },
  Responses: map[int]swagger.ContentValue{
    201: {
      Content: swagger.Content{
        "text/html": {Value: ""},
      },
    },
    401: {
      Content: swagger.Content{
        "application/json": {Value: &errorResponse{}},
      },
      Description: "invalid request",
    },
  },
})

router.AddRoute(http.MethodGet, "/users", okHandler, swagger.Definitions{
  Responses: map[int]swagger.ContentValue{
    200: {
      Content: swagger.Content{
        "application/json": {Value: &[]User{}},
      },
    },
  },
})

carSchema := openapi3.NewObjectSchema().WithProperties(map[string]*openapi3.Schema{
  "foo": openapi3.NewStringSchema(),
  "bar": openapi3.NewIntegerSchema().WithMax(15).WithMin(5),
})
requestBody := openapi3.NewRequestBody().WithJSONSchema(carSchema)
operation := swagger.NewOperation()
operation.AddRequestBody(requestBody)

router.AddRawRoute(http.MethodPost, "/cars", okHandler, operation)

router.GenerateAndExposeOpenapi()

This configuration will output the schema shown here.

Auto generated path params schema

The path params, if not set in schema, are auto generated from the path. The format of the path parameters depends on the router library you are using, as explained below.

Gorilla Mux

Gorilla Mux supports the path parameters as {someParam}, for example as in /users/{userId}.

Here is the example test.

The generated oas schema will contains userId, carId and driverId as path params set to string. If only one params is set, you must specify manually all the path params.

The generated OAS for this test case is visible here.

Fiber

Fiber supports the path parameters as :someParam, for example as in /users/:userId.

Here is the example test

SubRouter

It is possible to create a new sub router from the swagger.Router. It is possible to add a prefix to all the routes created under the specific router (instead of use the router specific methods, if given, or repeat the prefix for every route).

It could also be useful if you need a sub router to create a group of APIs which use the same middleware (for example,this could be achieved by the SubRouter features of gorilla mux, for example).

To see the SubRouter example, please see the integration test of one of the supported routers.

FAQ

1. How to add format binary? Formats date-time, email, hostname, ipv4, ipv6, uri could be added with tag jsonschema. Others format could be added with tag jsonschema_extra. Not all the formats are supported (see discovered unsupported formats here).

2. How to add a swagger with allOf? You can create manually a swagger with allOf using the AddRawRoute method.

3. How to add a swagger with anyOf? You can create manually a swagger with anyOf using the AddRawRoute method.

4. How to add a swagger with oneOf? You can create manually a swagger with oneOf using the AddRawRoute method, or use the jsonschema struct tag.

Discovered unsupported schema features

Formats:

• uuid is unsupported by kin-openapi

Versioning

We use SemVer for versioning. For the versions available, see the tags on this repository.