Add support for decoding content-language header from request

auth/handlers/handler.go

@@ -239,7 +239,7 @@ func (h *AuthHandlers) handle(fn handlerFn) http.HandlerFunc {
 			// because we need request's context to detect the language from!
 			ttf = func(t *template.Template) *template.Template {
 				return t.Funcs(map[string]interface{}{
-					"language": func() string { return locale.GetLanguageFromContext(req.Context()).String() },
+					"language": func() string { return locale.GetAcceptLanguageFromContext(req.Context()).String() },
 					"tr": func(key string, pp ...interface{}) template.HTML {
 						ss := make([]string, len(pp))
 						for i := range pp {

compose/service/module.go

@@ -131,7 +131,7 @@ func (svc module) Find(ctx context.Context, filter types.ModuleFilter) (set type
 		}
 
 		// i18n
-		tag := locale.GetLanguageFromContext(ctx)
+		tag := locale.GetAcceptLanguageFromContext(ctx)
 		set.Walk(func(m *types.Module) error {
 			m.DecodeTranslations(svc.locale.Locale().ResourceTranslations(tag, m.ResourceTranslation()))
 
@@ -353,7 +353,7 @@ func (svc module) updater(ctx context.Context, namespaceID, moduleID uint64, act
 			tt = append(tt, f.EncodeTranslations()...)
 		}
 
-		tt.SetLanguage(locale.GetLanguageFromContext(ctx))
+		tt.SetLanguage(locale.GetAcceptLanguageFromContext(ctx))
 		err = svc.locale.Upsert(ctx, tt)
 		if err != nil {
 			return err

compose/service/namespace.go

@@ -110,7 +110,7 @@ func (svc namespace) Find(ctx context.Context, filter types.NamespaceFilter) (se
 		}
 
 		// i18n
-		tag := locale.GetLanguageFromContext(ctx)
+		tag := locale.GetAcceptLanguageFromContext(ctx)
 		set.Walk(func(n *types.Namespace) error {
 			n.DecodeTranslations(svc.locale.Locale().ResourceTranslations(tag, n.ResourceTranslation()))
 			return nil

compose/service/page.go

@@ -144,7 +144,7 @@ func (svc page) search(ctx context.Context, filter types.PageFilter) (set types.
 		}
 
 		// i18n
-		tag := locale.GetLanguageFromContext(ctx)
+		tag := locale.GetAcceptLanguageFromContext(ctx)
 		set.Walk(func(p *types.Page) error {
 			p.DecodeTranslations(svc.locale.Locale().ResourceTranslations(tag, p.ResourceTranslation()))
 			return nil
@@ -362,7 +362,7 @@ func (svc page) updater(ctx context.Context, namespaceID, pageID uint64, action
 
 		// i18n
 		tt := p.EncodeTranslations()
-		tt.SetLanguage(locale.GetLanguageFromContext(ctx))
+		tt.SetLanguage(locale.GetAcceptLanguageFromContext(ctx))
 		err = svc.locale.Upsert(ctx, tt)
 		if err != nil {
 			return err
@@ -403,7 +403,7 @@ func (svc page) lookup(ctx context.Context, namespaceID uint64, lookup func(*pag
 			return err
 		}
 
-		p.DecodeTranslations(svc.locale.Locale().ResourceTranslations(locale.GetLanguageFromContext(ctx), p.ResourceTranslation()))
+		p.DecodeTranslations(svc.locale.Locale().ResourceTranslations(locale.GetAcceptLanguageFromContext(ctx), p.ResourceTranslation()))
 
 		aProps.setPage(p)
 

pkg/locale/context.go

@@ -6,15 +6,30 @@ import (
 	"golang.org/x/text/language"
 )
 
-func SetLanguageToContext(ctx context.Context, code language.Tag) context.Context {
+func SetAcceptLanguageToContext(ctx context.Context, code language.Tag) context.Context {
 	return context.WithValue(ctx, language.Tag{}, code)
 }
 
-// GetLanguageFromContext always returns language, either valid or default
-func GetLanguageFromContext(ctx context.Context) language.Tag {
+// GetAcceptLanguageFromContext always returns language, either valid or default
+func GetAcceptLanguageFromContext(ctx context.Context) language.Tag {
 	if tag, ok := ctx.Value(language.Tag{}).(language.Tag); ok {
 		return tag
 	} else {
 		return defaultLanguage
 	}
 }
+
+type contentLanguageCtx struct{}
+
+func SetContentLanguageToContext(ctx context.Context, code language.Tag) context.Context {
+	return context.WithValue(ctx, contentLanguageCtx{}, code)
+}
+
+// GetContentLanguageFromContext always returns language, either valid or default
+func GetContentLanguageFromContext(ctx context.Context) language.Tag {
+	if tag, ok := ctx.Value(contentLanguageCtx{}).(language.Tag); ok {
+		return tag
+	} else {
+		return language.Und
+	}
+}

pkg/locale/http.go

@@ -8,20 +8,48 @@ import (
 )
 
 const AcceptLanguageHeader = "Accept-Language"
+const ContentLanguageHeader = "Content-Language"
 
 func DetectLanguage(ll *service) func(next http.Handler) http.Handler {
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-			next.ServeHTTP(w, upgradeRequest(ll, r))
+			var ctx = r.Context()
+
+			// resolve accept-language header
+			ctx = SetAcceptLanguageToContext(ctx, resolveAcceptLanguageHeaders(ll, r))
+
+			// resolve content-language header
+			ctx = SetContentLanguageToContext(ctx, resolveContentLanguageHeaders(r.Header, ll.Default().Tag))
+
+			next.ServeHTTP(w, r.WithContext(ctx))
 		})
 	}
 }
 
-func upgradeRequest(ll *service, r *http.Request) *http.Request {
-	return r.WithContext(SetLanguageToContext(r.Context(), detectLanguage(ll, r)))
+// reads Content-Language headers from the request and returns
+// parsed value as language.Tag
+//
+// There are 4 valid scenarios for :
+//  - lang == 'skip':   returns und & services will (likely) ignore all translatable content
+//  - invalid language: (same as skip)
+//  - valid language:   returns valid language; services will treat translatable content from the payload as translations
+//  - no header:        returns default language; (same as valid language)
+func resolveContentLanguageHeaders(h http.Header, def language.Tag) language.Tag {
+	var cLang = h.Get(ContentLanguageHeader)
+
+	if cLang == "skip" || cLang == "" {
+		// more than 1 header or value equal to skip
+		return language.Und
+	}
+
+	if tag, err := language.Parse(cLang); err != nil {
+		return language.Und
+	} else {
+		return tag
+	}
 }
 
-func detectLanguage(ll *service, r *http.Request) (tag language.Tag) {
+func resolveAcceptLanguageHeaders(ll *service, r *http.Request) (tag language.Tag) {
 	if ll.opt.DevelopmentMode {
 		if err := ll.ReloadStatic(); err != nil {
 			// when in development mode, refresh languages for every request

pkg/locale/service.go

@@ -302,7 +302,7 @@ func (svc *service) LocalizedList(ctx context.Context) []*Language {
 	var (
 		l       *Language
 		ll      = make([]*Language, 0, len(svc.set))
-		reqLang = GetLanguageFromContext(ctx)
+		reqLang = GetAcceptLanguageFromContext(ctx)
 	)
 
 	for _, tag := range svc.tags {
@@ -365,7 +365,7 @@ func (svc *service) EncodeExternal(w io.Writer, app string, ll ...language.Tag)
 // Language is picked from the context
 func (svc *service) NS(ctx context.Context, ns string) func(key string, rr ...string) string {
 	var (
-		tag = GetLanguageFromContext(ctx)
+		tag = GetAcceptLanguageFromContext(ctx)
 	)
 
 	return func(key string, rr ...string) string {
@@ -377,7 +377,7 @@ func (svc *service) NS(ctx context.Context, ns string) func(key string, rr ...st
 //
 // Language is picked from the context
 func (svc *service) T(ctx context.Context, ns, key string, rr ...string) string {
-	return svc.t(GetLanguageFromContext(ctx), ns, key, rr...)
+	return svc.t(GetAcceptLanguageFromContext(ctx), ns, key, rr...)
 }
 
 // T returns translated key from namespaces using list of replacement pairs
@@ -392,7 +392,7 @@ func (svc *service) TFor(tag language.Tag, ns, key string, rr ...string) string
 // Language is picked from the context
 func (svc *service) TResource(ctx context.Context, ns, key string, rr ...string) string {
 
-	return svc.tResource(GetLanguageFromContext(ctx), ns, key, rr...)
+	return svc.tResource(GetAcceptLanguageFromContext(ctx), ns, key, rr...)
 }
 
 // TResourceFor returns translated key for resource using list of replacement pairs