new app.MiddlewareExists method

Author: kataras

HISTORY.md

@@ -24,6 +24,42 @@ Developers are not forced to upgrade if they don't really need it. Upgrade whene
 
 Changes apply to `main` branch.
 
+- New `Application/Party.MiddlewareExists(handlerNameOrHandler)` method added, example:
+
+```go
+package main
+
+import (
+	"fmt"
+
+	"github.com/kataras/iris/v12"
+	"github.com/kataras/iris/v12/x/errors"
+)
+
+func main() {
+	app := iris.New()
+
+	app.UseRouter(errors.RecoveryHandler)
+
+	if app.MiddlewareExists(errors.RecoveryHandler) { // <- HERE.
+		fmt.Println("errors.RecoveryHandler exists")
+	}
+	// OR:
+	// if app.MiddlewareExists("iris.errors.recover") {
+	// 	fmt.Println("Iris.Errors.Recovery exists")
+	// }
+
+	app.Get("/", indexHandler)
+
+	app.Listen(":8080")
+}
+
+func indexHandler(ctx iris.Context) {
+	panic("an error here")
+	ctx.HTML("<h1>Index</h1>")
+}
+
+```
 - New `x/errors.Intercept(func(ctx iris.Context, req *CreateRequest, resp *CreateResponse) error{ ... })` package-level function.
 
 ```go

context/handler.go

@@ -38,6 +38,7 @@ var (
 		"iris.logger",
 		"iris.rate",
 		"iris.methodoverride",
+		"iris.errors.recover",
 	}
 )
 
@@ -111,20 +112,6 @@ type Handler = func(*Context)
 // See `Handler` for more.
 type Handlers = []Handler
 
-// CopyHandlers returns a copy of "handlers" Handlers slice.
-func CopyHandlers(handlers []Handler) Handlers {
-	handlersCp := make([]Handler, 0, len(handlers))
-	for _, handler := range handlers {
-		if handler == nil {
-			continue
-		}
-
-		handlersCp = append(handlersCp, handler)
-	}
-
-	return handlersCp
-}
-
 func valueOf(v interface{}) reflect.Value {
 	if val, ok := v.(reflect.Value); ok {
 		return val
@@ -378,3 +365,50 @@ reg:
 
 	return h1
 }
+
+// CopyHandlers returns a copy of "handlers" Handlers slice.
+func CopyHandlers(handlers Handlers) Handlers {
+	handlersCp := make(Handlers, 0, len(handlers))
+	for _, handler := range handlers {
+		if handler == nil {
+			continue
+		}
+
+		handlersCp = append(handlersCp, handler)
+	}
+
+	return handlersCp
+}
+
+// HandlerExists reports whether a handler exists in the "handlers" slice.
+func HandlerExists(handlers Handlers, handlerNameOrFunc any) bool {
+	if handlerNameOrFunc == nil {
+		return false
+	}
+
+	var matchHandler func(any) bool
+
+	switch v := handlerNameOrFunc.(type) {
+	case string:
+		matchHandler = func(handler any) bool {
+			return HandlerName(handler) == v
+		}
+	case Handler:
+		handlerName := HandlerName(v)
+		matchHandler = func(handler any) bool {
+			return HandlerName(handler) == handlerName
+		}
+	default:
+		matchHandler = func(handler any) bool {
+			return reflect.TypeOf(handler) == reflect.TypeOf(v)
+		}
+	}
+
+	for _, handler := range handlers {
+		if matchHandler(handler) {
+			return true
+		}
+	}
+
+	return false
+}

core/router/api_builder.go

@@ -1370,6 +1370,26 @@ func (api *APIBuilder) DoneGlobal(handlers ...context.Handler) {
 	api.doneGlobalHandlers = append(api.doneGlobalHandlers, handlers...)
 }
 
+// MiddlewareExists reports whether the given handler exists in the middleware chain.
+func (api *APIBuilder) MiddlewareExists(handlerNameOrFunc any) bool {
+	if handlerNameOrFunc == nil {
+		return false
+	}
+
+	var handlers context.Handlers
+
+	if filter, ok := api.routerFilters[api]; ok {
+		handlers = append(handlers, filter.Handlers...)
+	}
+
+	handlers = append(handlers, api.middleware...)
+	handlers = append(handlers, api.doneHandlers...)
+	handlers = append(handlers, api.beginGlobalHandlers...)
+	handlers = append(handlers, api.doneGlobalHandlers...)
+
+	return context.HandlerExists(handlers, handlerNameOrFunc)
+}
+
 // RemoveHandler deletes a handler from begin and done handlers
 // based on its name or the handler pc function.
 // Note that UseGlobal and DoneGlobal handlers cannot be removed

core/router/party.go

@@ -234,6 +234,8 @@ type Party interface {
 	// Done appends to the very end, Handler(s) to the current Party's routes and child routes.
 	// The difference from .Use is that this/or these Handler(s) are being always running last.
 	Done(handlers ...context.Handler)
+	// MiddlewareExists reports whether the given handler exists in the middleware chain.
+	MiddlewareExists(handlerNameOrFunc any) bool
 	// RemoveHandler deletes a handler from begin and done handlers
 	// based on its name or the handler pc function.
 	//

iris_guide.go

@@ -4,6 +4,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/kataras/iris/v12/context"
 	"github.com/kataras/iris/v12/core/router"
 
 	"github.com/kataras/iris/v12/middleware/cors"
@@ -508,8 +509,13 @@ func (s *step7) Build() *Application {
 	app.SetContextErrorHandler(errors.DefaultContextErrorHandler)
 	app.Macros().SetErrorHandler(errors.DefaultPathParameterTypeErrorHandler)
 
-	app.UseRouter(recover.New())
-	app.UseRouter(s.step6.step5.routerMiddlewares...)
+	routeFilters := s.step6.step5.routerMiddlewares
+	if !context.HandlerExists(routeFilters, errors.RecoveryHandler) {
+		// If not errors.RecoveryHandler registered, then use the default one.
+		app.UseRouter(recover.New())
+	}
+
+	app.UseRouter(routeFilters...)
 	app.UseRouter(func(ctx Context) {
 		ctx.Header("Server", "Iris")
 		if dev := s.step6.step5.step4.step3.developer; dev != "" {

middleware/recover/recover.go

@@ -11,7 +11,7 @@ import (
 )
 
 func init() {
-	context.SetHandlerName("iris/middleware/recover.*", "iris.recover")
+	context.SetHandlerName("iris/middleware/recover.*", "iris.recover") // this name won't work because New() is a function that returns a handler.
 }
 
 // New returns a new recovery middleware,

x/errors/errors.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"log/slog"
 	"net/http"
 
 	"github.com/kataras/iris/v12/context"
@@ -20,6 +21,11 @@ type LogErrorFunc = func(ctx *context.Context, err error)
 // LogError can be modified to customize the way an error is logged to the server (most common: internal server errors, database errors et.c.).
 // Can be used to customize the error logging, e.g. using Sentry (cloud-based error console).
 var LogError LogErrorFunc = func(ctx *context.Context, err error) {
+	if ctx == nil {
+		slog.Error(err.Error())
+		return
+	}
+
 	ctx.Application().Logger().Error(err)
 }
 

x/errors/handlers.go

@@ -13,6 +13,10 @@ import (
 	"golang.org/x/exp/constraints"
 )
 
+func init() {
+	context.SetHandlerName("iris/x/errors.RecoveryHandler.*", "iris.errors.recover")
+}
+
 // RecoveryHandler is a middleware which recovers from panics and sends an appropriate error response
 // to the logger and the client.
 func RecoveryHandler(ctx *context.Context) {