applied sync.Once to make 'app' to be the only root App

internal/genny/actions/_fixtures/inputs/clean/actions/app.go

@@ -1,18 +1,23 @@
 package actions
 
 import (
+	"sync"
+
 	"github.com/gobuffalo/buffalo"
 )
 
-var app *buffalo.App
+var (
+	app     *buffalo.App
+	appOnce sync.Once
+)
 
 func App() *buffalo.App {
-	if app == nil {
+	appOnce.Do(func() {
 		app = buffalo.New(buffalo.Options{})
 		app.GET("/", HomeHandler)
 
 		app.ServeFiles("/", assetsBox) // serve files from the public directory
-	}
+	})
 
 	return app
 }

internal/genny/actions/_fixtures/outputs/clean/actions/app.go.tmpl

@@ -1,19 +1,24 @@
 package actions
 
 import (
+	"sync"
+
 	"github.com/gobuffalo/buffalo"
 )
 
-var app *buffalo.App
+var (
+	app     *buffalo.App
+	appOnce sync.Once
+)
 
 func App() *buffalo.App {
-	if app == nil {
+	appOnce.Do(func() {
 		app = buffalo.New(buffalo.Options{})
 		app.GET("/", HomeHandler)
 
 		app.GET("/user/index", UserIndex)
 		app.ServeFiles("/", assetsBox) // serve files from the public directory
-	}
+	})
 
 	return app
 }

internal/genny/actions/_fixtures/outputs/multi/actions/app.go.tmpl

@@ -1,20 +1,25 @@
 package actions
 
 import (
+	"sync"
+
 	"github.com/gobuffalo/buffalo"
 )
 
-var app *buffalo.App
+var (
+	app     *buffalo.App
+	appOnce sync.Once
+)
 
 func App() *buffalo.App {
-	if app == nil {
+	appOnce.Do(func() {
 		app = buffalo.New(buffalo.Options{})
 		app.GET("/", HomeHandler)
 
 		app.GET("/user/show", UserShow)
 		app.GET("/user/edit", UserEdit)
 		app.ServeFiles("/", assetsBox) // serve files from the public directory
-	}
+	})
 
 	return app
 }

internal/genny/actions/actions.go

@@ -68,6 +68,7 @@ func updateApp(pres *presenter) genny.RunFn {
 		if err != nil {
 			return err
 		}
+
 		var lines []string
 		body := f.String()
 		for _, a := range pres.Actions {
@@ -76,9 +77,19 @@ func updateApp(pres *presenter) genny.RunFn {
 				lines = append(lines, e)
 			}
 		}
-		f, err = gogen.AddInsideBlock(f, "app == nil", strings.Join(lines, "\n\t\t"))
+
+		f, err = gogen.AddInsideBlock(f, "appOnce.Do(func() {", strings.Join(lines, "\n\t\t"))
 		if err != nil {
-			return err
+			if strings.Contains(err.Error(), "could not find desired block") {
+				f, err = gogen.AddInsideBlock(f, "if app == nil {", strings.Join(lines, "\n\t\t"))
+				if err != nil {
+					return err
+				} else {
+					r.Logger.Warnf("This app was built with CLI v0.18.8 or older. See https://gobuffalo.io/documentation/known-issues/#cli-v0.18.8")
+				}
+			} else {
+				return err
+			}
 		}
 		return r.File(f)
 	}

internal/genny/newapp/api/templates/actions/app.go.tmpl

@@ -1,6 +1,8 @@
 package actions
 
 import (
+	"sync"
+
 	{{ if .opts.App.WithPop -}}
 	"{{ .opts.App.ModelsPkg }}"
 	{{ end -}}
@@ -24,8 +26,9 @@ import (
 var ENV = envy.Get("GO_ENV", "development")
 
 var (
-	app *buffalo.App
-	T   *i18n.Translator
+	app     *buffalo.App
+	appOnce sync.Once
+	T       *i18n.Translator
 )
 
 // App is where all routes and middleware for buffalo
@@ -42,7 +45,7 @@ var (
 // placed last in the route declarations, as it will prevent routes
 // declared after it to never be called.
 func App() *buffalo.App {
-	if app == nil {
+	appOnce.Do(func() {
 		app = buffalo.New(buffalo.Options{
 			Env:          ENV,
 			SessionStore: sessions.Null{},
@@ -69,7 +72,7 @@ func App() *buffalo.App {
 		{{ end -}}
 
 		app.GET("/", HomeHandler)
-	}
+	})
 
 	return app
 }

internal/genny/newapp/core/templates/actions/app.go.tmpl

@@ -1,6 +1,8 @@
 package actions
 
 import (
+	"sync"
+
 	"github.com/gobuffalo/buffalo"
 	"github.com/gobuffalo/envy"
 	forcessl "github.com/gobuffalo/mw-forcessl"
@@ -11,7 +13,11 @@ import (
 // ENV is used to help switch settings based on where the
 // application is being run. Default is "development".
 var ENV = envy.Get("GO_ENV", "development")
-var app *buffalo.App
+
+var (
+	app     *buffalo.App
+	appOnce sync.Once
+)
 
 // App is where all routes and middleware for buffalo
 // should be defined. This is the nerve center of your
@@ -27,7 +33,7 @@ var app *buffalo.App
 // placed last in the route declarations, as it will ensure routes
 // declared after it will never be called.
 func App() *buffalo.App {
-	if app == nil {
+	appOnce.Do(func() {
 		app = buffalo.New(buffalo.Options{
 			Env:         ENV,
 			SessionName: "_{{.opts.App.Name.File}}_session",
@@ -40,7 +46,7 @@ func App() *buffalo.App {
 		app.Use(paramlogger.ParameterLogger)
 
 		app.GET("/", HomeHandler)
-	}
+	})
 
 	return app
 }

internal/genny/newapp/web/templates/actions/app.go.tmpl

@@ -2,6 +2,7 @@ package actions
 
 import (
 	"net/http"
+	"sync"
 
 	"{{ .opts.App.PackagePkg }}/locales"
 	{{ if .opts.App.WithPop -}}
@@ -26,8 +27,9 @@ import (
 var ENV = envy.Get("GO_ENV", "development")
 
 var (
-	app *buffalo.App
-	T   *i18n.Translator
+	app     *buffalo.App
+	appOnce sync.Once
+	T       *i18n.Translator
 )
 
 // App is where all routes and middleware for buffalo
@@ -44,7 +46,7 @@ var (
 // placed last in the route declarations, as it will prevent routes
 // declared after it to never be called.
 func App() *buffalo.App {
-	if app == nil {
+	appOnce.Do(func() {
 		app = buffalo.New(buffalo.Options{
 			Env:         ENV,
 			SessionName: "_{{.opts.App.Name.File}}_session",
@@ -73,7 +75,7 @@ func App() *buffalo.App {
 		app.GET("/", HomeHandler)
 
 		app.ServeFiles("/", http.FS(public.FS())) // serve files from the public directory
-	}
+	})
 
 	return app
 }

internal/genny/resource/_fixtures/default/actions/app.go.tmpl

@@ -2,6 +2,7 @@ package actions
 
 import (
 	"net/http"
+	"sync"
 
 	"github.com/markbates/coke/locales"
 	"github.com/markbates/coke/public"
@@ -20,8 +21,9 @@ import (
 var ENV = envy.Get("GO_ENV", "development")
 
 var (
-	app *buffalo.App
-	T   *i18n.Translator
+	app     *buffalo.App
+	appOnce sync.Once
+	T       *i18n.Translator
 )
 
 // App is where all routes and middleware for buffalo
@@ -38,7 +40,7 @@ var (
 // placed last in the route declarations, as it will prevent routes
 // declared after it to never be called.
 func App() *buffalo.App {
-	if app == nil {
+	appOnce.Do(func() {
 		app = buffalo.New(buffalo.Options{
 			Env:         ENV,
 			SessionName: "_resource_session",
@@ -61,7 +63,7 @@ func App() *buffalo.App {
 
 		app.Resource("/widgets", WidgetsResource{})
 		app.ServeFiles("/", http.FS(public.FS())) // serve files from the public directory
-	}
+	})
 
 	return app
 }

internal/genny/resource/_fixtures/nested/actions/app.go.tmpl

@@ -2,6 +2,7 @@ package actions
 
 import (
 	"net/http"
+	"sync"
 
 	"github.com/markbates/coke/locales"
 	"github.com/markbates/coke/public"
@@ -20,8 +21,9 @@ import (
 var ENV = envy.Get("GO_ENV", "development")
 
 var (
-	app *buffalo.App
-	T   *i18n.Translator
+	app     *buffalo.App
+	appOnce sync.Once
+	T       *i18n.Translator
 )
 
 // App is where all routes and middleware for buffalo
@@ -38,7 +40,7 @@ var (
 // placed last in the route declarations, as it will prevent routes
 // declared after it to never be called.
 func App() *buffalo.App {
-	if app == nil {
+	appOnce.Do(func() {
 		app = buffalo.New(buffalo.Options{
 			Env:         ENV,
 			SessionName: "_resource_session",
@@ -61,7 +63,7 @@ func App() *buffalo.App {
 
 		app.Resource("/admin/widgets", AdminWidgetsResource{})
 		app.ServeFiles("/", http.FS(public.FS())) // serve files from the public directory
-	}
+	})
 
 	return app
 }

internal/genny/resource/actions.go

@@ -2,6 +2,7 @@ package resource
 
 import (
 	"fmt"
+	"strings"
 
 	"github.com/gobuffalo/flect/name"
 	"github.com/gobuffalo/genny/v2"
@@ -14,11 +15,22 @@ func addResource(pres presenter) genny.RunFn {
 		if err != nil {
 			return err
 		}
+
 		stmt := fmt.Sprintf("app.Resource(\"/%s\", %sResource{})", pres.Name.URL(), pres.Name.Resource())
-		f, err = gogen.AddInsideBlock(f, "if app == nil {", stmt)
+		f, err = gogen.AddInsideBlock(f, "appOnce.Do(func() {", stmt)
 		if err != nil {
-			return err
+			if strings.Contains(err.Error(), "could not find desired block") {
+				f, err = gogen.AddInsideBlock(f, "if app == nil {", stmt)
+				if err != nil {
+					return err
+				} else {
+					r.Logger.Warnf("This app was built with CLI v0.18.8 or older. See https://gobuffalo.io/documentation/known-issues/#cli-v0.18.8")
+				}
+			} else {
+				return err
+			}
 		}
+
 		return r.File(f)
 	}
 }