Refactor i18n, use Locale to provide i18n/translation related functions (#18648)

* remove unnecessary web context data fields, and unify the i18n/translation related functions to `Locale`
* in development, show an error if a translation key is missing
* remove the unnecessary loops `for _, lang := range translation.AllLangs()` for every request, which improves the performance slightly
* use `ctx.Locale.Language()` instead of `ctx.Data["Lang"].(string)`
* add more comments about how the Locale/LangType fields are used

modules/context/context.go

@@ -38,7 +38,6 @@ import (
 	"gitea.com/go-chi/session"
 	chi "github.com/go-chi/chi/v5"
 	"github.com/unknwon/com"
-	"github.com/unknwon/i18n"
 	"github.com/unrolled/render"
 	"golang.org/x/crypto/pbkdf2"
 )
@@ -738,15 +737,7 @@ func Contexter() func(next http.Handler) http.Handler {
 			ctx.Data["UnitProjectsGlobalDisabled"] = unit.TypeProjects.UnitGlobalDisabled()
 
 			ctx.Data["i18n"] = locale
-			ctx.Data["Tr"] = i18n.Tr
-			ctx.Data["Lang"] = locale.Language()
 			ctx.Data["AllLangs"] = translation.AllLangs()
-			for _, lang := range translation.AllLangs() {
-				if lang.Lang == locale.Language() {
-					ctx.Data["LangName"] = lang.Name
-					break
-				}
-			}
 
 			next.ServeHTTP(ctx.Resp, ctx.Req)
 

modules/translation/translation.go

@@ -25,17 +25,18 @@ type Locale interface {
 
 // LangType represents a lang type
 type LangType struct {
-	Lang, Name string
+	Lang, Name string // these fields are used directly in templates: {{range .AllLangs}}{{.Lang}}{{.Name}}{{end}}
 }
 
 var (
 	matcher       language.Matcher
-	allLangs      []LangType
+	allLangs      []*LangType
+	allLangMap    map[string]*LangType
 	supportedTags []language.Tag
 )
 
 // AllLangs returns all supported languages sorted by name
-func AllLangs() []LangType {
+func AllLangs() []*LangType {
 	return allLangs
 }
 
@@ -81,14 +82,17 @@ func InitLocales() {
 	}
 	i18n.SetDefaultLang("en-US")
 
-	allLangs = make([]LangType, 0, i18n.Count()-1)
+	allLangs = make([]*LangType, 0, i18n.Count())
+	allLangMap = map[string]*LangType{}
 	langs := i18n.ListLangs()
-	names := i18n.ListLangDescs()
+	descs := i18n.ListLangDescs()
 	for i, v := range langs {
-		allLangs = append(allLangs, LangType{v, names[i]})
+		l := &LangType{v, descs[i]}
+		allLangs = append(allLangs, l)
+		allLangMap[v] = l
 	}
 
-	// Sort languages case insensitive according to their name - needed for the user settings
+	// Sort languages case-insensitive according to their name - needed for the user settings
 	sort.Slice(allLangs, func(i, j int) bool {
 		return strings.ToLower(allLangs[i].Name) < strings.ToLower(allLangs[j].Name)
 	})
@@ -102,13 +106,18 @@ func Match(tags ...language.Tag) language.Tag {
 
 // locale represents the information of localization.
 type locale struct {
-	Lang string
+	Lang, LangName string // these fields are used directly in templates: .i18n.Lang
 }
 
 // NewLocale return a locale
 func NewLocale(lang string) Locale {
+	langName := "unknown"
+	if l, ok := allLangMap[lang]; ok {
+		langName = l.Name
+	}
 	return &locale{
-		Lang: lang,
+		Lang:     lang,
+		LangName: langName,
 	}
 }
 
@@ -118,7 +127,16 @@ func (l *locale) Language() string {
 
 // Tr translates content to target language.
 func (l *locale) Tr(format string, args ...interface{}) string {
-	return i18n.Tr(l.Lang, format, args...)
+	if setting.IsProd {
+		return i18n.Tr(l.Lang, format, args...)
+	}
+
+	// in development, we should show an error if a translation key is missing
+	s, ok := TryTr(l.Lang, format, args...)
+	if !ok {
+		log.Error("missing i18n translation key: %q", format)
+	}
+	return s
 }
 
 // Language specific rules for translating plural texts