Add path `Prefix` option

[jamietanna]

oapi-codegen/echo-middleware#15 / #40

[ChepChaf]

I have an use case where we use /api/v{n} as a basepath for the API and the middleware isn't able to handle it, this PR would fix it, any way I can help?

[jamietanna]

Hey, that's awesome! I guess any additional test cases we can put into #40 - and once we get round to finishing off that PR doing a test with your own workload, that'd be awesome 🤞🏽

[jarangutan]

I did get around it for now by doing

// path is the mount point i.e. `/api/v1`
func withSwaggerValidate(path string) func(http.Handler) http.Handler {
	swagger, err := oapigen.GetSwagger()
	if err != nil {
		// This should never error
		panic("there was an error getting the swagger")
	}

	// The openapi spec does not do prefixes yet (e.g. looking at `/templates` instead of `/api/v1/templates`)
	// To validate spec, need to update paths to match the prefix passed in
	updatedPaths := openapi3.Paths{}
	for key, value := range swagger.Paths.Map() {
		updatedPaths.Set(path+key, value)
	}

	// Clear out the servers array in the swagger spec. It is recommended to do this so that it skips validating
	// that server names match.
	swagger.Servers = nil

	f := middleware.OapiRequestValidator(swagger)
	return func(next http.Handler) http.Handler {
		return f(next)
	}
}

[Rakhmanov]

Alternative workaround that worked for me:

	apiBase := "/v1"
	loader := openapi3.NewLoader()
	loader.IsExternalRefsAllowed = true

	doc, err := loader.LoadFromFile(filepath.Join("openapi", "api.yaml"))
	if err != nil {
		panic(err)
	}

	// Manually setting servers to necessary prefix
	doc.Servers = openapi3.Servers{
		&openapi3.Server{URL: apiBase + "/"},
	}

	validator := nethttpmw.OapiRequestValidatorWithOptions(doc,
		&nethttpmw.Options{
			DoNotValidateServers:  false,
			SilenceServersWarning: true,
			Options: openapi3filter.Options{
				AuthenticationFunc:         openapi3filter.NoopAuthenticationFunc,
			}})


	validated := validator(protected)

[Fedott]

Hello,
I have prepared a PR (#54) with a straightforward implementation of this feature. All tests are passing, and I am already using this implementation in my production system.
Could you please review it and provide feedback if necessary?
It would be great to have this feature included in the upcoming release.