add accesslog+MVC example

Author: kataras

_examples/logging/request-logger/accesslog/access.log.sample

@@ -7,4 +7,4 @@
 2020-09-13 13:38:18 0s 401 GET /admin ::1 0 B 0 B
 2020-09-13 13:38:19 0s 200 GET /admin ::1 auth=admin:admin 0 B 48 B
 2020-09-13 13:38:22 0s 200 GET /session ::1 session_id=23fe763f-c9d5-4d65-9e1a-2cc8d23d1aa3 session_test_key=session_test_value auth=admin:admin 0 B 2 B
-2020-09-13 13:38:25 2.0001204s 200 GET /fields ::1 job_latency=2s auth=admin:admin 0 B 2 B
+2020-09-13 13:38:25 2.0001204s 200 GET /fields ::1 job_latency=2s auth=admin:admin user=user-id:user-name 0 B 2 B

_examples/logging/request-logger/accesslog/main.go

@@ -159,6 +159,16 @@ func sessionHandler(ctx iris.Context) {
 	ctx.WriteString("OK")
 }
 
+type user struct {
+	ID       string
+	Username string
+}
+
+// Log custom structs, they can implement the fmt.Stringer interface too.
+func (u user) String() string {
+	return u.ID + ":" + u.Username
+}
+
 func fieldsHandler(ctx iris.Context) {
 	start := time.Now()
 	// simulate a heavy job...
@@ -169,5 +179,13 @@ func fieldsHandler(ctx iris.Context) {
 	logFields := accesslog.GetFields(ctx)
 	logFields.Set("job_latency", end.Round(time.Second))
 
+	// Simulate a database fetch or anything
+	// to get a "user" and log it:
+	u := user{
+		ID:       "user-id",
+		Username: "user-name",
+	}
+	logFields.Set("user", u)
+
 	ctx.WriteString("OK")
 }

_examples/mvc/basic/main.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 
 	"github.com/kataras/iris/v12"
+	"github.com/kataras/iris/v12/middleware/accesslog"
 	"github.com/kataras/iris/v12/middleware/recover"
 	"github.com/kataras/iris/v12/sessions"
 
@@ -12,31 +13,40 @@ import (
 
 func main() {
 	app := iris.New()
-	app.Use(recover.New())
 	app.Logger().SetLevel("debug")
-	// Disable verbose logging of routes for this and its children parties
-	// when the log level is "debug": app.SetRoutesNoLog(true)
-	mvc.Configure(app.Party("/basic"), basicMVC)
+
+	basic := app.Party("/basic")
+	{
+		// Register middlewares to run under the /basic path prefix.
+		ac := accesslog.File("./basic_access.log")
+		defer ac.Close()
+
+		basic.UseRouter(ac.Handler)
+		basic.UseRouter(recover.New())
+
+		mvc.Configure(basic, basicMVC)
+	}
 
 	app.Listen(":8080")
 }
 
 func basicMVC(app *mvc.Application) {
 	// Disable verbose logging of controllers for this and its children mvc apps
-	// when the log level is "debug": app.SetControllersNoLog(true)
+	// when the log level is "debug":
+	app.SetControllersNoLog(true)
 
-	// You can use normal middlewares at MVC apps of course.
-	app.Router.Use(func(ctx iris.Context) {
-		ctx.Application().Logger().Infof("Path: %s", ctx.Path())
-		ctx.Next()
-	})
+	// You can still register middlewares at MVC apps of course.
+	// The app.Router returns the Party that this MVC
+	// was registered on.
+	// app.Router.UseRouter/Use/....
 
 	// Register dependencies which will be binding to the controller(s),
 	// can be either a function which accepts an iris.Context and returns a single value (dynamic binding)
 	// or a static struct value (service).
 	app.Register(
 		sessions.New(sessions.Config{}).Start,
 		&prefixedLogger{prefix: "DEV"},
+		accesslog.GetFields, // Set custom fields through a controller or controller's methods.
 	)
 
 	// GET: http://localhost:8080/basic
@@ -73,9 +83,9 @@ func (s *prefixedLogger) Log(msg string) {
 }
 
 type basicController struct {
-	Logger LoggerService
-
-	Session *sessions.Session
+	Logger    LoggerService     // the static logger service attached to this app.
+	Session   *sessions.Session // current HTTP session.
+	LogFields *accesslog.Fields // accesslog middleware custom fields.
 }
 
 func (c *basicController) BeforeActivation(b mvc.BeforeActivation) {
@@ -90,6 +100,7 @@ func (c *basicController) AfterActivation(a mvc.AfterActivation) {
 
 func (c *basicController) Get() string {
 	count := c.Session.Increment("count", 1)
+	c.LogFields.Set("count", count)
 
 	body := fmt.Sprintf("Hello from basicController\nTotal visits from you: %d", count)
 	c.Logger.Log(body)

middleware/accesslog/accesslog.go

@@ -31,6 +31,9 @@ const (
 // GetFields returns the accesslog fields for this request.
 // Returns a store which the caller can use to
 // set/get/remove custom log fields. Use its `Set` method.
+//
+// To use with MVC: Register(accesslog.GetFields).
+// DI Handlers: ConfigureContainer().RegisterDependency(accesslog.GetFields).
 func GetFields(ctx *context.Context) (fields *Fields) {
 	if v := ctx.Values().Get(fieldsContextKey); v != nil {
 		fields = v.(*Fields)
@@ -60,7 +63,6 @@ func shouldSkip(ctx *context.Context) bool {
 }
 
 type (
-
 	// Fields is a type alias for memstore.Store, used to set
 	// more than one field at serve-time. Same as FieldExtractor.
 	Fields = memstore.Store