examples: update the cors example to be easier for beginners

And update the pug view engine's vendor jade template engine to yesterday version 1 (tested and worked) to fix https://github.com/kataras/iris/issues/1125


Former-commit-id: 0ea7a8dd97ab13e5ecf984c379234cc671f5d84e

_examples/http_request/request-logger/request-logger-file-json/main.go

@@ -0,0 +1,134 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"runtime"
+	"strings"
+	"time"
+
+	"github.com/kataras/iris"
+	"github.com/kataras/iris/middleware/logger"
+
+	"github.com/kataras/golog"
+)
+
+const deleteFileOnExit = false
+
+func main() {
+	app := iris.New()
+
+	logFile := newLogFile()
+	defer func() {
+		logFile.Close()
+		if deleteFileOnExit {
+			os.Remove(logFile.Name())
+		}
+	}()
+
+	// Handle the logs by yourself using the `app.Logger#Handle` method.
+	// Return true if that handled, otherwise will print to the screen.
+	// You can also use the `app.Logger#SetOutput/AddOutput` to change or add
+	// multi (io.Writer) outputs if you just want to print the message
+	// somewhere else than the terminal screen.
+	app.Logger().Handle(func(l *golog.Log) bool {
+		_, fn, line, _ := runtime.Caller(5)
+
+		var (
+			// formatted date string based on the `golog#TimeFormat`, which can be customized.
+			// Or use the golog.Log#Time field to get the exact time.Time instance.
+			datetime = l.FormatTime()
+			// the log's message level.
+			level = golog.GetTextForLevel(l.Level, false)
+			// the log's message.
+			message = l.Message
+			// the source code line of where it is called,
+			// this can differ on your app, see runtime.Caller(%d).
+			source = fmt.Sprintf("%s#%d", fn, line)
+		)
+
+		// You can always use a custom json structure and json.Marshal and logFile.Write(its result)
+		// but it is faster to just build your JSON string by yourself as we do below.
+		jsonStr := fmt.Sprintf(`{"datetime":"%s","level":"%s","message":"%s","source":"%s"}`, datetime, level, message, source)
+		fmt.Fprintln(logFile, jsonStr)
+
+		/* Example output:
+		{"datetime":"2018/10/31 13:13","level":"[INFO]","message":"My server started","source":"c:/mygopath/src/github.com/kataras/iris/_examples/http_request/request-logger/request-logger-file-json/main.go#71"}
+		*/
+		return true
+	})
+
+	r := newRequestLogger()
+
+	app.Use(r)
+	app.OnAnyErrorCode(r, func(ctx iris.Context) {
+		ctx.HTML("<h1> Error: Please try <a href ='/'> this </a> instead.</h1>")
+	})
+
+	h := func(ctx iris.Context) {
+		ctx.Writef("Hello from %s", ctx.Path())
+	}
+
+	app.Get("/", h)
+
+	app.Get("/1", h)
+
+	app.Get("/2", h)
+
+	app.Logger().Info("My server started")
+	// http://localhost:8080
+	// http://localhost:8080/1
+	// http://localhost:8080/2
+	// http://lcoalhost:8080/notfoundhere
+	app.Run(iris.Addr(":8080"), iris.WithoutServerError(iris.ErrServerClosed))
+}
+
+var excludeExtensions = [...]string{
+	".js",
+	".css",
+	".jpg",
+	".png",
+	".ico",
+	".svg",
+}
+
+func newRequestLogger() iris.Handler {
+	c := logger.Config{
+		Status: true,
+		IP:     true,
+		Method: true,
+		Path:   true,
+	}
+
+	//	we don't want to use the logger
+	// to log requests to assets and etc
+	c.AddSkipper(func(ctx iris.Context) bool {
+		path := ctx.Path()
+		for _, ext := range excludeExtensions {
+			if strings.HasSuffix(path, ext) {
+				return true
+			}
+		}
+		return false
+	})
+
+	return logger.New(c)
+}
+
+// get a filename based on the date, file logs works that way the most times
+// but these are just a sugar.
+func todayFilename() string {
+	today := time.Now().Format("Jan 02 2006")
+	return today + ".json"
+}
+
+func newLogFile() *os.File {
+	filename := todayFilename()
+	// open an output file, this will append to the today's file if server restarted.
+	f, err := os.OpenFile(filename, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0666)
+	if err != nil {
+		panic(err)
+	}
+
+	return f
+}