Preferred language for the user

api/App.Tests/ApiEndpointsTests.cs

@@ -212,8 +212,9 @@ public class ProductionAuthTests(ProductionApiTestFactory factory) : IClassFixtu
     {
       username = "editor",
       password = "editorpass",
-      isAdmin = false,
+      displayName = "Editor User",
-      displayName = "Editor User"
+      preferredLanguage = "fi",
+      roles = Array.Empty<string>()
     });
 
     Assert.Equal(HttpStatusCode.Created, createResponse.StatusCode);
@@ -227,14 +228,16 @@ public class ProductionAuthTests(ProductionApiTestFactory factory) : IClassFixtu
     var updateResponse = await _client.PutAsJsonAsync("/users/editor", new
     {
       password = "editorpass2",
-      isAdmin = true,
+      displayName = "Editor Admin",
-      displayName = "Editor Admin"
+      preferredLanguage = "en",
+      roles = new[] { "admin" }
     });
 
     Assert.Equal(HttpStatusCode.OK, updateResponse.StatusCode);
     var updatedUser = await updateResponse.Content.ReadFromJsonAsync<UserDto>();
     Assert.NotNull(updatedUser);
-    Assert.True(updatedUser.IsAdmin);
+    Assert.Contains("admin", updatedUser.Roles);
+    Assert.Equal("en", updatedUser.PreferredLanguage);
     Assert.Equal("Editor Admin", updatedUser.DisplayName);
 
     var deleteResponse = await _client.DeleteAsync("/users/editor");
@@ -332,7 +335,9 @@ public class AuthTokenDto
 
   public string DisplayName { get; set; } = string.Empty;
 
-  public bool IsAdmin { get; set; }
+  public string PreferredLanguage { get; set; } = string.Empty;
+
+  public List<string> Roles { get; set; } = [];
 
   public string TokenType { get; set; } = string.Empty;
 
@@ -347,7 +352,9 @@ public class UserDto
 
   public DateTime LastUpdated { get; set; }
 
-  public bool IsAdmin { get; set; }
-
   public string DisplayName { get; set; } = string.Empty;
+
+  public string PreferredLanguage { get; set; } = string.Empty;
+
+  public List<string> Roles { get; set; } = [];
 }

api/App/Endpoints/AuthEndpoints.cs

@@ -53,6 +53,7 @@ public static class AuthEndpoints
         new(ClaimTypes.Name, authenticatedUser.Username),
         new("username", authenticatedUser.Username),
         new("display_name", authenticatedUser.DisplayName),
+        new("preferred_language", authenticatedUser.PreferredLanguage),
       };
 
       foreach (var role in authenticatedUser.Roles)
@@ -74,6 +75,7 @@ public static class AuthEndpoints
         AccessToken = tokenValue,
         Username = authenticatedUser.Username,
         DisplayName = authenticatedUser.DisplayName,
+        PreferredLanguage = authenticatedUser.PreferredLanguage,
         Roles = authenticatedUser.Roles,
         TokenType = "Bearer",
         ExpiresIn = 43200

api/App/Models/AppUser.cs

@@ -6,6 +6,23 @@ public static class AppRoles
   public static readonly IReadOnlyList<string> All = [Lok, Admin];
 }
 
+public static class AppLanguages
+{
+  public const string Finnish = "fi";
+  public const string English = "en";
+  public const string Slovak = "sk";
+
+  public static readonly IReadOnlyList<string> All = [Finnish, English, Slovak];
+
+  public static string NormalizeOrDefault(string? language)
+  {
+    var normalized = language?.Trim().ToLowerInvariant();
+    return !string.IsNullOrWhiteSpace(normalized) && All.Contains(normalized)
+      ? normalized
+      : Finnish;
+  }
+}
+
 public class AppUser
 {
   public long Id { get; set; }
@@ -20,6 +37,8 @@ public class AppUser
 
   public string DisplayName { get; set; } = string.Empty;
 
+  public string PreferredLanguage { get; set; } = AppLanguages.Finnish;
+
   public List<string> Roles { get; set; } = [];
 }
 
@@ -33,6 +52,8 @@ public class AppUserView
 
   public string DisplayName { get; set; } = string.Empty;
 
+  public string PreferredLanguage { get; set; } = AppLanguages.Finnish;
+
   public List<string> Roles { get; set; } = [];
 }
 
@@ -44,6 +65,8 @@ public class AppUserCreateRequest
 
   public string DisplayName { get; set; } = string.Empty;
 
+  public string PreferredLanguage { get; set; } = AppLanguages.Finnish;
+
   public List<string> Roles { get; set; } = [];
 }
 
@@ -53,5 +76,7 @@ public class AppUserUpdateRequest
 
   public string DisplayName { get; set; } = string.Empty;
 
+  public string PreferredLanguage { get; set; } = AppLanguages.Finnish;
+
   public List<string> Roles { get; set; } = [];
 }

api/App/Program.cs

@@ -241,6 +241,22 @@ public class Program
                         SELECT id, 'admin' FROM Users WHERE isAdmin = 1;";
                     command.ExecuteNonQuery();
                 }
+
+                // Migration: add preferredLanguage to Users if missing and backfill with Finnish
+                command.CommandText = "SELECT COUNT(*) FROM pragma_table_info('Users') WHERE name = 'preferredLanguage';";
+                var usersHasPreferredLanguage = Convert.ToInt32(command.ExecuteScalar()) > 0;
+
+                if (!usersHasPreferredLanguage)
+                {
+                    command.CommandText = "ALTER TABLE Users ADD COLUMN preferredLanguage TEXT NOT NULL DEFAULT 'fi';";
+                    command.ExecuteNonQuery();
+                }
+
+                command.CommandText = @"
+                    UPDATE Users
+                    SET preferredLanguage = 'fi'
+                    WHERE preferredLanguage IS NULL OR TRIM(preferredLanguage) = '';";
+                command.ExecuteNonQuery();
             }
         }
 

api/App/Services/UserService.cs

@@ -19,12 +19,13 @@ public class UserService
 
     await using var upsertCommand = _connection.CreateCommand();
     upsertCommand.CommandText = @"
-      INSERT INTO Users (username, password, added, lastUpdated, displayName)
+      INSERT INTO Users (username, password, added, lastUpdated, displayName, preferredLanguage)
-      VALUES (@username, @password, @added, @lastUpdated, @displayName)
+      VALUES (@username, @password, @added, @lastUpdated, @displayName, @preferredLanguage)
       ON CONFLICT(username) DO UPDATE SET
         password = excluded.password,
         lastUpdated = excluded.lastUpdated,
-        displayName = excluded.displayName;
+        displayName = excluded.displayName,
+        preferredLanguage = excluded.preferredLanguage;
       SELECT id FROM Users WHERE username = @username;";
 
     upsertCommand.Parameters.AddWithValue("@username", normalizedUsername);
@@ -32,6 +33,7 @@ public class UserService
     upsertCommand.Parameters.AddWithValue("@added", now.ToString("O"));
     upsertCommand.Parameters.AddWithValue("@lastUpdated", now.ToString("O"));
     upsertCommand.Parameters.AddWithValue("@displayName", admin.DisplayName.Trim());
+    upsertCommand.Parameters.AddWithValue("@preferredLanguage", AppLanguages.Finnish);
 
     var userId = Convert.ToInt64(await upsertCommand.ExecuteScalarAsync());
 
@@ -49,7 +51,7 @@ public class UserService
 
     await using var command = _connection.CreateCommand();
     command.CommandText = @"
-      SELECT u.id, u.username, u.password, u.added, u.lastUpdated, u.displayName,
+      SELECT u.id, u.username, u.password, u.added, u.lastUpdated, u.displayName, u.preferredLanguage,
              GROUP_CONCAT(ur.roleName) AS roles
       FROM Users u
       LEFT JOIN UserRoles ur ON ur.userId = u.id
@@ -81,7 +83,7 @@ public class UserService
 
     await using var command = _connection.CreateCommand();
     command.CommandText = @"
-      SELECT u.id, u.username, u.added, u.lastUpdated, u.displayName,
+      SELECT u.id, u.username, u.added, u.lastUpdated, u.displayName, u.preferredLanguage,
              GROUP_CONCAT(ur.roleName) AS roles
       FROM Users u
       LEFT JOIN UserRoles ur ON ur.userId = u.id
@@ -99,6 +101,7 @@ public class UserService
         Added = ParseDate(reader["added"]?.ToString()),
         LastUpdated = ParseDate(reader["lastUpdated"]?.ToString()),
         DisplayName = reader["displayName"]?.ToString() ?? string.Empty,
+        PreferredLanguage = AppLanguages.NormalizeOrDefault(reader["preferredLanguage"]?.ToString()),
         Roles = ParseRoles(reader["roles"]?.ToString())
       });
     }
@@ -112,11 +115,12 @@ public class UserService
 
     var now = DateTime.UtcNow;
     var normalizedUsername = request.Username.Trim().ToLowerInvariant();
+    var preferredLanguage = AppLanguages.NormalizeOrDefault(request.PreferredLanguage);
 
     await using var insertCommand = _connection.CreateCommand();
     insertCommand.CommandText = @"
-      INSERT INTO Users (username, password, added, lastUpdated, displayName)
+      INSERT INTO Users (username, password, added, lastUpdated, displayName, preferredLanguage)
-      VALUES (@username, @password, @added, @lastUpdated, @displayName);
+      VALUES (@username, @password, @added, @lastUpdated, @displayName, @preferredLanguage);
       SELECT last_insert_rowid();";
 
     insertCommand.Parameters.AddWithValue("@username", normalizedUsername);
@@ -124,6 +128,7 @@ public class UserService
     insertCommand.Parameters.AddWithValue("@added", now.ToString("O"));
     insertCommand.Parameters.AddWithValue("@lastUpdated", now.ToString("O"));
     insertCommand.Parameters.AddWithValue("@displayName", request.DisplayName.Trim());
+    insertCommand.Parameters.AddWithValue("@preferredLanguage", preferredLanguage);
 
     var insertedId = Convert.ToInt64(await insertCommand.ExecuteScalarAsync());
 
@@ -143,6 +148,7 @@ public class UserService
       Added = now,
       LastUpdated = now,
       DisplayName = request.DisplayName.Trim(),
+      PreferredLanguage = preferredLanguage,
       Roles = validRoles
     };
   }
@@ -153,6 +159,7 @@ public class UserService
 
     var normalizedUsername = username.Trim().ToLowerInvariant();
     var now = DateTime.UtcNow;
+    var preferredLanguage = AppLanguages.NormalizeOrDefault(request.PreferredLanguage);
 
     var currentUser = await GetUserByUsername(normalizedUsername);
     if (currentUser is null)
@@ -165,13 +172,15 @@ public class UserService
       UPDATE Users
       SET password = @password,
           lastUpdated = @lastUpdated,
-          displayName = @displayName
+          displayName = @displayName,
+          preferredLanguage = @preferredLanguage
       WHERE username = @username;";
 
     command.Parameters.AddWithValue("@username", normalizedUsername);
     command.Parameters.AddWithValue("@password", string.IsNullOrWhiteSpace(request.Password) ? currentUser.Password : request.Password);
     command.Parameters.AddWithValue("@lastUpdated", now.ToString("O"));
     command.Parameters.AddWithValue("@displayName", request.DisplayName.Trim());
+    command.Parameters.AddWithValue("@preferredLanguage", preferredLanguage);
 
     var affectedRows = await command.ExecuteNonQueryAsync();
     if (affectedRows == 0)
@@ -192,6 +201,7 @@ public class UserService
       Added = currentUser.Added,
       LastUpdated = now,
       DisplayName = request.DisplayName.Trim(),
+      PreferredLanguage = preferredLanguage,
       Roles = validRoles
     };
   }
@@ -225,7 +235,7 @@ public class UserService
 
     await using var command = _connection.CreateCommand();
     command.CommandText = @"
-      SELECT u.id, u.username, u.added, u.lastUpdated, u.displayName,
+      SELECT u.id, u.username, u.added, u.lastUpdated, u.displayName, u.preferredLanguage,
              GROUP_CONCAT(ur.roleName) AS roles
       FROM Users u
       LEFT JOIN UserRoles ur ON ur.userId = u.id
@@ -247,6 +257,7 @@ public class UserService
       Added = ParseDate(reader["added"]?.ToString()),
       LastUpdated = ParseDate(reader["lastUpdated"]?.ToString()),
       DisplayName = reader["displayName"]?.ToString() ?? string.Empty,
+      PreferredLanguage = AppLanguages.NormalizeOrDefault(reader["preferredLanguage"]?.ToString()),
       Roles = ParseRoles(reader["roles"]?.ToString())
     };
   }
@@ -272,7 +283,7 @@ public class UserService
   {
     await using var command = _connection.CreateCommand();
     command.CommandText = @"
-      SELECT u.id, u.username, u.password, u.added, u.lastUpdated, u.displayName,
+      SELECT u.id, u.username, u.password, u.added, u.lastUpdated, u.displayName, u.preferredLanguage,
              GROUP_CONCAT(ur.roleName) AS roles
       FROM Users u
       LEFT JOIN UserRoles ur ON ur.userId = u.id
@@ -301,6 +312,7 @@ public class UserService
       Added = ParseDate(reader["added"]?.ToString()),
       LastUpdated = ParseDate(reader["lastUpdated"]?.ToString()),
       DisplayName = reader["displayName"]?.ToString() ?? string.Empty,
+      PreferredLanguage = AppLanguages.NormalizeOrDefault(reader["preferredLanguage"]?.ToString()),
       Roles = ParseRoles(reader["roles"]?.ToString())
     };
   }

api/Database/init.sql

@@ -16,7 +16,8 @@ CREATE TABLE IF NOT EXISTS Users (
   password TEXT NOT NULL,
   added TEXT NOT NULL,
   lastUpdated TEXT NOT NULL,
-  displayName TEXT NOT NULL DEFAULT ''
+  displayName TEXT NOT NULL DEFAULT '',
+  preferredLanguage TEXT NOT NULL DEFAULT 'fi'
 );
 
 CREATE TABLE IF NOT EXISTS UserRoles (

ui/src/api/index.ts

@@ -4,6 +4,7 @@ type AuthTokenResponse = {
   accessToken: string;
   username: string;
   displayName: string;
+  preferredLanguage: "fi" | "en" | "sk";
   roles: string[];
   tokenType: string;
   expiresIn: number;
@@ -64,6 +65,7 @@ export type User = {
   added: string;
   lastUpdated: string;
   displayName: string;
+  preferredLanguage: "fi" | "en" | "sk";
   roles: string[];
 };
 
@@ -71,12 +73,14 @@ export type CreateUserInput = {
   username: string;
   password: string;
   displayName: string;
+  preferredLanguage: "fi" | "en" | "sk";
   roles: string[];
 };
 
 export type UpdateUserInput = {
   password?: string;
   displayName: string;
+  preferredLanguage: "fi" | "en" | "sk";
   roles: string[];
 };
 

ui/src/app.tsx

@@ -19,12 +19,14 @@ function AppShell() {
   const setSession = useSetRecoilState(sessionAtom);
 
   useEffect(() => {
-    initializeLanguage(setLanguage);
+    const storedPreferredLanguage = localStorage.getItem("session-preferred-language");
+    initializeLanguage(setLanguage, storedPreferredLanguage === "en" || storedPreferredLanguage === "sk" ? storedPreferredLanguage : "fi");
   }, [setLanguage]);
 
   useEffect(() => {
     const storedUsername = localStorage.getItem("session-username");
     const storedDisplayName = localStorage.getItem("session-display-name");
+    const storedPreferredLanguage = localStorage.getItem("session-preferred-language");
     const storedRoles = localStorage.getItem("session-roles");
     const storedToken = localStorage.getItem("session-token");
     if (!storedUsername || !storedDisplayName || !storedToken) {
@@ -35,6 +37,7 @@ function AppShell() {
     setSession({
       username: storedUsername,
       displayName: storedDisplayName,
+      preferredLanguage: storedPreferredLanguage === "en" || storedPreferredLanguage === "sk" ? storedPreferredLanguage : "fi",
       roles: (storedRoles ?? "").split(",").filter(Boolean),
       token: storedToken,
     });

ui/src/components/Nav.tsx

@@ -15,7 +15,8 @@ export default function Nav() {
     setSession(null);
     localStorage.removeItem("session-username");
     localStorage.removeItem("session-display-name");
-    localStorage.removeItem("session-is-admin");
+    localStorage.removeItem("session-preferred-language");
+    localStorage.removeItem("session-roles");
     localStorage.removeItem("session-token");
     navigate("/login");
   };

ui/src/i18n.ts

@@ -71,6 +71,10 @@ const translations = {
     "management.username": "Username",
     "management.password": "Password",
     "management.displayName": "Display name",
+    "management.preferredLanguage": "Preferred language",
+    "management.language.fi": "Finnish",
+    "management.language.en": "English",
+    "management.language.sk": "Slovak",
     "management.added": "Added",
     "management.updated": "Last updated",
     "management.loading": "Loading users...",
@@ -156,6 +160,10 @@ const translations = {
     "management.username": "Käyttäjätunnus",
     "management.password": "Salasana",
     "management.displayName": "Näyttönimi",
+    "management.preferredLanguage": "Ensisijainen kieli",
+    "management.language.fi": "Suomi",
+    "management.language.en": "Englanti",
+    "management.language.sk": "Slovakki",
     "management.added": "Lisätty",
     "management.updated": "Viimeksi päivitetty",
     "management.loading": "Ladataan käyttäjiä...",
@@ -243,6 +251,10 @@ const translations = {
     "management.username": "Používateľské meno",
     "management.password": "Heslo",
     "management.displayName": "Zobrazované meno",
+    "management.preferredLanguage": "Preferovaný jazyk",
+    "management.language.fi": "Fínčina",
+    "management.language.en": "Angličtina",
+    "management.language.sk": "Slovenčina",
     "management.added": "Pridané",
     "management.updated": "Naposledy aktualizované",
     "management.loading": "Načítavajú sa používatelia...",
@@ -268,11 +280,19 @@ const translations = {
 export type TranslationKey = keyof typeof translations.en;
 
 export const normalizeLanguage = (value: unknown): Language =>
-  value === "fi" || value === "sk" ? value : "en";
+  value === "en" || value === "sk" ? value : "fi";
 
-export const initializeLanguage = (setLanguage: (lang: Language) => void) => {
+export const initializeLanguage = (
-  const stored = normalizeLanguage(localStorage.getItem(STORAGE_KEY));
+  setLanguage: (lang: Language) => void,
-  setLanguage(stored);
+  fallbackLanguage?: Language,
+) => {
+  const storedValue = localStorage.getItem(STORAGE_KEY);
+  if (storedValue !== null) {
+    setLanguage(normalizeLanguage(storedValue));
+    return;
+  }
+
+  setLanguage(normalizeLanguage(fallbackLanguage));
 };
 
 export const useLanguage = () => {

ui/src/routes/login.tsx

@@ -2,11 +2,12 @@ import { FormEvent, useEffect, useState } from "react";
 import { useNavigate } from "react-router-dom";
 import { useRecoilState } from "recoil";
 import { requestAuthToken } from "~/api";
-import { useT } from "~/i18n";
+import { normalizeLanguage, useLanguage, useT } from "~/i18n";
 import { sessionAtom } from "~/state/appState";
 
 export default function Login() {
   const t = useT();
+  const { setLanguage } = useLanguage();
   const navigate = useNavigate();
   const [session, setSession] = useRecoilState(sessionAtom);
   const [username, setUsername] = useState("");
@@ -38,12 +39,17 @@ export default function Login() {
       setSession({
         username: auth.username,
         displayName: auth.displayName,
+        preferredLanguage: auth.preferredLanguage,
         roles: auth.roles,
         token: auth.accessToken,
       });
 
+      const preferredLanguage = normalizeLanguage(auth.preferredLanguage);
+      setLanguage(preferredLanguage);
+
       localStorage.setItem("session-username", auth.username);
       localStorage.setItem("session-display-name", auth.displayName);
+      localStorage.setItem("session-preferred-language", preferredLanguage);
       localStorage.setItem("session-roles", auth.roles.join(","));
       localStorage.setItem("session-token", auth.accessToken);
       setError("");

ui/src/routes/management.tsx

@@ -5,6 +5,7 @@ import { useT } from "~/i18n";
 const AVAILABLE_ROLES = ["lok", "admin"];
 
 type Mode = "create" | "edit";
+type LanguageOption = "fi" | "en" | "sk";
 
 export default function Management() {
   const t = useT();
@@ -13,6 +14,7 @@ export default function Management() {
   const [username, setUsername] = useState("");
   const [password, setPassword] = useState("");
   const [displayName, setDisplayName] = useState("");
+  const [preferredLanguage, setPreferredLanguage] = useState<LanguageOption>("fi");
   const [selectedRoles, setSelectedRoles] = useState<Set<string>>(new Set());
   const [selectedUsername, setSelectedUsername] = useState("");
   const [error, setError] = useState("");
@@ -44,6 +46,7 @@ export default function Management() {
     setUsername("");
     setPassword("");
     setDisplayName("");
+    setPreferredLanguage("fi");
     setSelectedRoles(new Set());
     setSelectedUsername("");
   };
@@ -53,6 +56,7 @@ export default function Management() {
     setUsername(user.username);
     setPassword("");
     setDisplayName(user.displayName);
+    setPreferredLanguage(user.preferredLanguage);
     setSelectedRoles(new Set(user.roles));
     setSelectedUsername(user.username);
     setError("");
@@ -81,12 +85,14 @@ export default function Management() {
           username: username.trim(),
           password: password,
           displayName: displayName.trim(),
+          preferredLanguage,
           roles: [...selectedRoles],
         });
       } else {
         await updateUser(selectedUsername, {
           password: password.trim() ? password : undefined,
           displayName: displayName.trim(),
+          preferredLanguage,
           roles: [...selectedRoles],
         });
       }
@@ -153,6 +159,20 @@ export default function Management() {
           />
         </label>
 
+        <label htmlFor="management-language" className="block text-left">
+          {t("management.preferredLanguage")}
+          <select
+            id="management-language"
+            value={preferredLanguage}
+            onChange={(event) => setPreferredLanguage(event.target.value as LanguageOption)}
+            className="mt-1 block w-full rounded-md border border-[#C99763] bg-[#FFF7EE] px-4 py-2 focus:outline-none focus:ring-2 focus:ring-[#A56C38]"
+          >
+            <option value="fi">{t("management.language.fi")}</option>
+            <option value="en">{t("management.language.en")}</option>
+            <option value="sk">{t("management.language.sk")}</option>
+          </select>
+        </label>
+
         <div className="block text-left">
           <span className="block">{t("management.rolesAssign")}</span>
           <div className="mt-1 flex flex-wrap gap-3">
@@ -210,6 +230,9 @@ export default function Management() {
                     <div className="text-xs text-[#8E4F24]">
                       {t("management.updated")}: {new Date(user.lastUpdated).toLocaleString()}
                     </div>
+                    <div className="text-xs text-[#8E4F24]">
+                      {t("management.preferredLanguage")}: {t(`management.language.${user.preferredLanguage}` as "management.language.fi" | "management.language.en" | "management.language.sk")}
+                    </div>
                     {user.roles.length > 0 ? (
                       <div className="mt-1 flex flex-wrap gap-1">
                         {user.roles.map((role) => (

ui/src/state/appState.ts

@@ -6,6 +6,7 @@ export type Language = "fi" | "en" | "sk";
 export type Session = {
   username: string;
   displayName: string;
+  preferredLanguage: Language;
   roles: string[];
   token: string;
 };
@@ -19,7 +20,7 @@ export type Toast = {
 
 export const languageAtom = atom<Language>({
   key: "languageAtom",
-  default: "en",
+  default: "fi",
 });
 
 export const sessionAtom = atom<Session | null>({