reorganization of _examples and add some new examples such as iris+groupcache+mysql+docker

Former-commit-id: ed635ee95de7160cde11eaabc0c1dcb0e460a620

_examples/request-body/read-custom-via-unmarshaler/main.go

@@ -0,0 +1,72 @@
+package main
+
+import (
+	"gopkg.in/yaml.v3"
+
+	"github.com/kataras/iris/v12"
+)
+
+func main() {
+	app := newApp()
+
+	// use Postman or whatever to do a POST request
+	// (however you are always free to use app.Get and GET http method requests to read body of course)
+	// to the http://localhost:8080 with RAW BODY:
+	/*
+		addr: localhost:8080
+		serverName: Iris
+	*/
+	//
+	// The response should be:
+	// Received: main.config{Addr:"localhost:8080", ServerName:"Iris"}
+	app.Listen(":8080", iris.WithOptimizations)
+}
+
+func newApp() *iris.Application {
+	app := iris.New()
+	app.Post("/", handler)
+
+	return app
+}
+
+// simple yaml stuff, read more at https://github.com/go-yaml/yaml
+type config struct {
+	Addr       string `yaml:"addr"`
+	ServerName string `yaml:"serverName"`
+}
+
+/*
+type myBodyDecoder struct{}
+
+var DefaultBodyDecoder = myBodyDecoder{}
+
+// Implements the `kataras/iris/context#Unmarshaler` but at our example
+// we will use the simplest `context#UnmarshalerFunc` to pass just the yaml.Unmarshal.
+//
+// Can be used as: ctx.UnmarshalBody(&c, DefaultBodyDecoder)
+func (r *myBodyDecoder) Unmarshal(data []byte, outPtr interface{}) error {
+	return yaml.Unmarshal(data, outPtr)
+}
+*/
+
+func handler(ctx iris.Context) {
+	var c config
+
+	//
+	// Note:
+	// yaml.Unmarshal already implements the `context#Unmarshaler`
+	// so we can use it directly, like the json.Unmarshal(ctx.ReadJSON), xml.Unmarshal(ctx.ReadXML)
+	// and every library which follows the best practises and is aligned with the Go standards.
+	//
+	// Note 2:
+	// If you need to read the body again for any reason
+	// you should disable the body consumption via `app.Run(..., iris.WithoutBodyConsumptionOnUnmarshal)`.
+	//
+
+	if err := ctx.UnmarshalBody(&c, iris.UnmarshalerFunc(yaml.Unmarshal)); err != nil {
+		ctx.StopWithError(iris.StatusBadRequest, err)
+		return
+	}
+
+	ctx.Writef("Received: %#+v", c)
+}