[MM-49265] Update translations when config is changed (#21987)

* update translations when config is changed

* wrap and return the error message

* use the configs directly instead of diff

api4/config.go

@@ -13,6 +13,7 @@ import (
 	"github.com/mattermost/mattermost-server/v6/audit"
 	"github.com/mattermost/mattermost-server/v6/config"
 	"github.com/mattermost/mattermost-server/v6/model"
+	"github.com/mattermost/mattermost-server/v6/shared/i18n"
 	"github.com/mattermost/mattermost-server/v6/shared/mlog"
 	"github.com/mattermost/mattermost-server/v6/utils"
 )
@@ -184,6 +185,15 @@ func updateConfig(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	// If the config for default server locale has changed, reinitialize the server's translations.
+	if oldCfg.LocalizationSettings.DefaultServerLocale != newCfg.LocalizationSettings.DefaultServerLocale {
+		s := newCfg.LocalizationSettings
+		if err = i18n.InitTranslations(*s.DefaultServerLocale, *s.DefaultClientLocale); err != nil {
+			c.Err = model.NewAppError("updateConfig", "api.config.update_config.translations.app_error", nil, "", http.StatusInternalServerError).Wrap(err)
+			return
+		}
+	}
+
 	diffs, err := config.Diff(oldCfg, newCfg)
 	if err != nil {
 		c.Err = model.NewAppError("updateConfig", "api.config.update_config.diff.app_error", nil, "", http.StatusInternalServerError).Wrap(err)

api4/team_test.go

@@ -93,6 +93,30 @@ func TestCreateTeam(t *testing.T) {
 		CheckForbiddenStatus(t, resp)
 	})
 
+	t.Run("should take under consideration the server language when creating a new team", func(t *testing.T) {
+		c := th.SystemAdminClient
+		cfg, _, err := c.GetConfig()
+		require.NoError(t, err)
+		newServerLang := "de"
+		cfg.LocalizationSettings.DefaultServerLocale = &newServerLang
+		translateFunc := i18n.GetUserTranslations(newServerLang)
+
+		_, _, err = c.UpdateConfig(cfg)
+		require.NoError(t, err)
+
+		team := th.CreateTeamWithClient(c)
+		channels, _, err := c.GetPublicChannelsForTeam(team.Id, 0, 1000, "")
+		require.NoError(t, err)
+		for _, ch := range channels {
+			if ch.Name == "off-topic" {
+				require.Equal(t, translateFunc("api.channel.create_default_channels.off_topic"), ch.DisplayName)
+			}
+			if ch.Name == "town-square" {
+				require.Equal(t, translateFunc("api.channel.create_default_channels.town_square"), ch.DisplayName)
+			}
+		}
+	})
+
 	t.Run("cloud limit reached returns 400", func(t *testing.T) {
 		th.App.Srv().SetLicense(model.NewTestLicense("cloud"))
 

i18n/en.json

@@ -1534,6 +1534,10 @@
     "id": "api.config.update_config.restricted_merge.app_error",
     "translation": "Failed to merge given config."
   },
+  {
+    "id": "api.config.update_config.translations.app_error",
+    "translation": "Failed to update server translations."
+  },
   {
     "id": "api.context.404.app_error",
     "translation": "Sorry, we could not find the page."