chai is an extension for a few popular http routers that adds support for type safe http handlers via Go 1.18's generics. This allows it to also generate a swagger spec by automatically detecting the request/response types, http methods, route paths and path params.
chai uses swaggo/swag annotations for the parts of the swagger spec that cannot be automatically inferred.
chai is still a work in progress
-
YAML marshalling
Currently only https://github.com/ghodss/yaml is supported as a yaml marshaller for the generated swagger spec, which is also provided via
openapi2.MarshalYAML()as an alias
- chi - ./examples/chi
- gorilla/mux - ./examples/gorilla
- standalone repo - https://github.com/go-chai/examples
This swagger.yaml is generated by the program below. Notice that the spec for the PostHandler handler was generated without any annotations. The request/response types and the route were detected automatically from the router itself.
package main
import (
"fmt"
"net/http"
"strconv"
chai "github.com/go-chai/chai/chi"
_ "github.com/go-chai/chai/examples/docs/basic" // This is required to be able to serve the stored swagger spec in prod
"github.com/go-chai/chai/examples/shared/model"
"github.com/go-chai/chai/openapi2"
"github.com/go-chi/chi/v5"
"github.com/go-openapi/spec"
httpSwagger "github.com/swaggo/http-swagger"
)
func main() {
r := chi.NewRouter()
r.Route("/api/v1", func(r chi.Router) {
r.Route("/examples", func(r chi.Router) {
chai.Post(r, "/post", PostHandler)
chai.Get(r, "/calc", CalcHandler)
chai.Get(r, "/ping", PingHandler)
chai.Get(r, "/groups/{group_id}/accounts/{account_id}", PathParamsHandler)
chai.Get(r, "/header", HeaderHandler)
chai.Get(r, "/securities", SecuritiesHandler)
chai.Get(r, "/attribute", AttributeHandler)
})
})
// This must be used only during development to generate the swagger spec
docs, err := chai.OpenAPI2(r)
if err != nil {
panic(fmt.Sprintf("failed to generate the swagger spec: %+v", err))
}
// This should be used in prod to serve the swagger spec
r.Get("/swagger/*", httpSwagger.Handler(
httpSwagger.URL("http://localhost:8080/swagger/doc.json"), //The url pointing to API definition
))
addCustomDocs(docs)
openapi2.LogYAML(docs)
// This must be used only during development to store the swagger spec
err = openapi2.WriteDocs(docs, &openapi2.GenConfig{
OutputDir: "examples/docs/basic",
})
if err != nil {
panic(fmt.Sprintf("failed to write the swagger spec: %+v", err))
}
fmt.Println("The swagger spec is available at http://localhost:8080/swagger/")
http.ListenAndServe(":8080", r)
}
type Error struct {
Message string `json:"error"`
ErrorDebug string `json:"error_debug,omitempty"`
ErrorDescription string `json:"error_description,omitempty"`
StatusCode int `json:"status_code,omitempty"`
}
func (e *Error) Error() string {
return e.Message
}
func PostHandler(account *model.Account, w http.ResponseWriter, r *http.Request) (*model.Account, int, *Error) {
return account, http.StatusOK, nil
}
// @Param val1 query int true "used for calc"
// @Param val2 query int true "used for calc"
// @Success 203
// @Failure 400,404
func CalcHandler(w http.ResponseWriter, r *http.Request) (string, int, error) {
val1, err := strconv.Atoi(r.URL.Query().Get("val1"))
if err != nil {
return "", http.StatusBadRequest, err
}
val2, err := strconv.Atoi(r.URL.Query().Get("val2"))
if err != nil {
return "", http.StatusBadRequest, err
}
return fmt.Sprintf("%d", val1*val2), http.StatusOK, nil
}
// PingExample godoc
// @Summary ping example
// @Description do ping
// @Tags example
func PingHandler(w http.ResponseWriter, r *http.Request) (string, int, error) {
return "pong", http.StatusOK, nil
}
// PathParamsHandler godoc
// @Summary path params example
// @Description path params
// @Tags example
// @Param group_id path int true "Group ID"
// @Param account_id path int true "Account ID"
// @Failure 400,404
func PathParamsHandler(w http.ResponseWriter, r *http.Request) (string, int, error) {
groupID, err := strconv.Atoi(chi.URLParam(r, "group_id"))
if err != nil {
return "", http.StatusBadRequest, err
}
accountID, err := strconv.Atoi(chi.URLParam(r, "account_id"))
if err != nil {
return "", http.StatusBadRequest, err
}
return fmt.Sprintf("group_id=%d account_id=%d", groupID, accountID), http.StatusOK, nil
}
// HeaderHandler godoc
// @Summary custome header example
// @Description custome header
// @Tags example
// @Param Authorization header string true "Authentication header"
// @Failure 400,404
func HeaderHandler(w http.ResponseWriter, r *http.Request) (string, int, error) {
return r.Header.Get("Authorization"), http.StatusOK, nil
}
// SecuritiesHandler godoc
// @Summary custome header example
// @Description custome header
// @Tags example
// @Param Authorization header string true "Authentication header"
// @Failure 400,404
// @Security ApiKeyAuth
func SecuritiesHandler(w http.ResponseWriter, r *http.Request) (string, int, error) {
return "ok", http.StatusOK, nil
}
// AttributeHandler godoc
// @Summary attribute example
// @Description attribute
// @Tags example
// @Param enumstring query string false "string enums" Enums(A, B, C)
// @Param enumint query int false "int enums" Enums(1, 2, 3)
// @Param enumnumber query number false "int enums" Enums(1.1, 1.2, 1.3)
// @Param string query string false "string valid" minlength(5) maxlength(10)
// @Param int query int false "int valid" minimum(1) maximum(10)
// @Param default query string false "string default" default(A)
// @Success 200 "answer"
// @Failure 400,404 "ok"
func AttributeHandler(w http.ResponseWriter, r *http.Request) (string, int, error) {
return fmt.Sprintf("enumstring=%s enumint=%s enumnumber=%s string=%s int=%s default=%s",
r.URL.Query().Get("enumstring"),
r.URL.Query().Get("enumint"),
r.URL.Query().Get("enumnumber"),
r.URL.Query().Get("string"),
r.URL.Query().Get("int"),
r.URL.Query().Get("default"),
), http.StatusOK, nil
}
func addCustomDocs(docs *spec.Swagger) {
docs.Swagger = "2.0"
docs.Host = "localhost:8080"
docs.Info = &spec.Info{
InfoProps: spec.InfoProps{
Description: "This is a sample celler server.",
Title: "Swagger Example API",
TermsOfService: "http://swagger.io/terms/",
Contact: &spec.ContactInfo{
ContactInfoProps: spec.ContactInfoProps{
Name: "API Support",
URL: "http://www.swagger.io/support",
Email: "[email protected]",
},
},
License: &spec.License{
LicenseProps: spec.LicenseProps{
Name: "Apache 2.0",
URL: "http://www.apache.org/licenses/LICENSE-2.0.html",
},
},
Version: "1.0",
},
}
docs.SecurityDefinitions = map[string]*spec.SecurityScheme{
"ApiKeyAuth": {
SecuritySchemeProps: spec.SecuritySchemeProps{
Type: "apiKey",
In: "header",
Name: "Authorization",
},
},
}
}