Protect changing in parallel using HTTP 412 precondition failed

Makefile

@@ -1,3 +1,18 @@
+start: examples/base/pocketbase
+	examples/base/pocketbase serve --dir examples/base/data
+
+examples/base/pocketbase: **/*.go ui/dist lubinas/dist
+	go build -o examples/base/pocketbase examples/base/main.go
+
+ui/dist: ui/node_modules ui/vite.config.js ui/index.html ui/src/**/* ui/public/**/*
+	npm --prefix ui run build
+
+ui/node_modules: ui/package.json
+	npm --prefix ui install
+
+clean:
+	rm -rf ui/node_modules examples/base/pocketbase
+
 lint:
 	golangci-lint run -c ./golangci.yml ./...
 

examples/base/main.go

@@ -3,129 +3,51 @@ package main
 import (
 	"log"
 	"net/http"
-	"os"
-	"path/filepath"
 
 	"github.com/pocketbase/pocketbase"
-	"github.com/pocketbase/pocketbase/apis"
 	"github.com/pocketbase/pocketbase/core"
-	"github.com/pocketbase/pocketbase/plugins/ghupdate"
-	"github.com/pocketbase/pocketbase/plugins/jsvm"
-	"github.com/pocketbase/pocketbase/plugins/migratecmd"
-	"github.com/pocketbase/pocketbase/tools/hook"
-	"github.com/pocketbase/pocketbase/tools/osutils"
 )
 
 func main() {
 	app := pocketbase.New()
 
-	// ---------------------------------------------------------------
+	app.OnRecordViewRequest().BindFunc(addLastModified)
-	// Optional plugin flags:
-	// ---------------------------------------------------------------
 
-	var hooksDir string
+	app.OnRecordUpdateRequest().BindFunc(ifUnmodifiedSince)
-	app.RootCmd.PersistentFlags().StringVar(
-		&hooksDir,
-		"hooksDir",
-		"",
-		"the directory with the JS app hooks",
-	)
 
-	var hooksWatch bool
+	app.OnRecordDeleteRequest().BindFunc(ifUnmodifiedSince)
-	app.RootCmd.PersistentFlags().BoolVar(
-		&hooksWatch,
-		"hooksWatch",
-		true,
-		"auto restart the app on pb_hooks file change; it has no effect on Windows",
-	)
-
-	var hooksPool int
-	app.RootCmd.PersistentFlags().IntVar(
-		&hooksPool,
-		"hooksPool",
-		15,
-		"the total prewarm goja.Runtime instances for the JS app hooks execution",
-	)
-
-	var migrationsDir string
-	app.RootCmd.PersistentFlags().StringVar(
-		&migrationsDir,
-		"migrationsDir",
-		"",
-		"the directory with the user defined migrations",
-	)
-
-	var automigrate bool
-	app.RootCmd.PersistentFlags().BoolVar(
-		&automigrate,
-		"automigrate",
-		true,
-		"enable/disable auto migrations",
-	)
-
-	var publicDir string
-	app.RootCmd.PersistentFlags().StringVar(
-		&publicDir,
-		"publicDir",
-		defaultPublicDir(),
-		"the directory to serve static files",
-	)
-
-	var indexFallback bool
-	app.RootCmd.PersistentFlags().BoolVar(
-		&indexFallback,
-		"indexFallback",
-		true,
-		"fallback the request to index.html on missing static path, e.g. when pretty urls are used with SPA",
-	)
-
-	app.RootCmd.ParseFlags(os.Args[1:])
-
-	// ---------------------------------------------------------------
-	// Plugins and hooks:
-	// ---------------------------------------------------------------
-
-	// load jsvm (pb_hooks and pb_migrations)
-	jsvm.MustRegister(app, jsvm.Config{
-		MigrationsDir: migrationsDir,
-		HooksDir:      hooksDir,
-		HooksWatch:    hooksWatch,
-		HooksPoolSize: hooksPool,
-	})
-
-	// migrate command (with js templates)
-	migratecmd.MustRegister(app, app.RootCmd, migratecmd.Config{
-		TemplateLang: migratecmd.TemplateLangJS,
-		Automigrate:  automigrate,
-		Dir:          migrationsDir,
-	})
-
-	// GitHub selfupdate
-	ghupdate.MustRegister(app, app.RootCmd, ghupdate.Config{})
-
-	// static route to serves files from the provided public dir
-	// (if publicDir exists and the route path is not already defined)
-	app.OnServe().Bind(&hook.Handler[*core.ServeEvent]{
-		Func: func(e *core.ServeEvent) error {
-			if !e.Router.HasRoute(http.MethodGet, "/{path...}") {
-				e.Router.GET("/{path...}", apis.Static(os.DirFS(publicDir), indexFallback))
-			}
-
-			return e.Next()
-		},
-		Priority: 999, // execute as latest as possible to allow users to provide their own route
-	})
 
 	if err := app.Start(); err != nil {
 		log.Fatal(err)
 	}
 }
 
-// the default pb_public dir location is relative to the executable
+func addLastModified(e *core.RecordRequestEvent) error {
-func defaultPublicDir() string {
+	updated := e.Record.GetString("updated")
-	if osutils.IsProbablyGoRun() {
+
-		return "./pb_public"
+	if updated != "" {
+		e.Response.Header().Add("Last-Modified", updated)
 	}
 
-	return filepath.Join(os.Args[0], "../pb_public")
+	return e.Next()
+}
+
+func ifUnmodifiedSince(e *core.RecordRequestEvent) error {
+	updated := e.Record.GetString("updated")
+
+	if updated != "" {
+		header := e.Request.Header.Get("If-Unmodified-Since")
+
+		if header == "" || header != updated {
+			e.Response.Header().Add("Last-Modified", updated)
+
+			if header == "" {
+				return e.Error(http.StatusPreconditionRequired, "Header If-Unmodified-Since is required", nil)
+			} else if header != updated {
+				return e.Error(http.StatusPreconditionFailed, "Record was modified after retrieval", nil)
+			}
+		}
+	}
+
+	return e.Next()
 }

ui/src/components/records/RecordUpsertPanel.svelte

@@ -278,7 +278,11 @@
             if (isNew) {
                 result = await ApiClient.collection(collection.id).create(data);
             } else {
-                result = await ApiClient.collection(collection.id).update(record.id, data);
+                result = await ApiClient.collection(collection.id).update(record.id, data, {
+                    headers: {
+                        "If-Unmodified-Since": record.updated,
+                    },
+                });
             }
 
             addSuccessToast(isNew ? "Successfully created record." : "Successfully updated record.");
@@ -318,7 +322,11 @@
 
         confirm(`Do you really want to delete the selected record?`, () => {
             return ApiClient.collection(original.collectionId)
-                .delete(original.id)
+                .delete(original.id, {
+                    headers: {
+                        "If-Unmodified-Since": record.updated,
+                    },
+                })
                 .then(() => {
                     forceHide();
                     addSuccessToast("Successfully deleted record.");