Set default `TimeZone` to empty and get from local time.

docs/en/Community-Articles/2025-03-11-Developing-A-Multi-Timezone-Application-Using-The-ABP-Framework/post.md

@@ -8,7 +8,7 @@ In this article, we'll show you step by step how to handle multi-timezone in the
 
 ## Timezone Settings
 
-The ABP framework provides a setting called `Abp.Timing.TimeZone` for setting and getting the timezone of users, tenants, or applications. The default value is `UTC`. Check out the [Timing documentation](https://abp.io/docs/latest/framework/infrastructure/timing) for more information.
+The ABP framework provides a setting called `Abp.Timing.TimeZone` for setting and getting the timezone of users, tenants, or applications. The default value is empty, which means the application will use the server's time zone. Check out the [Timing documentation](https://abp.io/docs/latest/framework/infrastructure/timing) for more information.
 
 ## ISO 8601 Date Time Format
 

docs/en/framework/infrastructure/timing.md

@@ -157,7 +157,7 @@ This section covers the ABP infrastructure related to managing time zones.
 
 ### TimeZone Setting
 
-ABP defines **a setting**, named `Abp.Timing.TimeZone`, that can be used to set and get the time zone for a user, [tenant](../architecture/multi-tenancy) or globally for the application. The default value is `UTC`.
+ABP defines **a setting**, named `Abp.Timing.TimeZone`, that can be used to set and get the time zone for a user, [tenant](../architecture/multi-tenancy) or globally for the application. The default value is empty, which means the application will use the server's time zone.
 
 You can change your host/tenant global time zone in the [Settings Management UI](../../modules/setting-management#setting-management-ui)
 

framework/src/Volo.Abp.AspNetCore/Microsoft/AspNetCore/Timing/AbpTimeZoneMiddleware.cs

@@ -34,10 +34,9 @@ public class AbpTimeZoneMiddleware : AbpMiddlewareBase, ITransientDependency
             timezone = await settingProvider.GetOrNullAsync(TimingSettingNames.TimeZone);
         }
 
-        if (timezone.IsNullOrEmpty())
+        if (timezone.IsNullOrWhiteSpace())
         {
-            await next(context);
-            return;
+            timezone = context.RequestServices.GetRequiredService<ITimezoneProvider>().GetCurrentIanaTimezoneName();
         }
 
         var currentTimezoneProvider = context.RequestServices.GetRequiredService<ICurrentTimezoneProvider>();

framework/src/Volo.Abp.Http.Client/Volo/Abp/Http/Client/ClientProxying/ClientProxyBase.cs

@@ -20,6 +20,7 @@ using Volo.Abp.Json;
 using Volo.Abp.MultiTenancy;
 using Volo.Abp.Reflection;
 using Volo.Abp.Threading;
+using Volo.Abp.Timing;
 using Volo.Abp.Tracing;
 
 namespace Volo.Abp.Http.Client.ClientProxying;
@@ -33,6 +34,7 @@ public class ClientProxyBase<TService> : ITransientDependency
     protected ICorrelationIdProvider CorrelationIdProvider => LazyServiceProvider.LazyGetRequiredService<ICorrelationIdProvider>();
     protected ICurrentTenant CurrentTenant => LazyServiceProvider.LazyGetRequiredService<ICurrentTenant>();
     protected IOptions<AbpCorrelationIdOptions> AbpCorrelationIdOptions => LazyServiceProvider.LazyGetRequiredService<IOptions<AbpCorrelationIdOptions>>();
+    protected ICurrentTimezoneProvider CurrentTimezoneProvider => LazyServiceProvider.LazyGetRequiredService<ICurrentTimezoneProvider>();
     protected IProxyHttpClientFactory HttpClientFactory => LazyServiceProvider.LazyGetRequiredService<IProxyHttpClientFactory>();
     protected IRemoteServiceConfigurationProvider RemoteServiceConfigurationProvider => LazyServiceProvider.LazyGetRequiredService<IRemoteServiceConfigurationProvider>();
     protected IOptions<AbpHttpClientOptions> ClientOptions => LazyServiceProvider.LazyGetRequiredService<IOptions<AbpHttpClientOptions>>();
@@ -337,6 +339,12 @@ public class ClientProxyBase<TService> : ITransientDependency
 
         //X-Requested-With
         requestMessage.Headers.Add("X-Requested-With", "XMLHttpRequest");
+
+        //Timezone
+        if (!CurrentTimezoneProvider.TimeZone.IsNullOrWhiteSpace())
+        {
+            requestMessage.Headers.Add(TimeZoneConsts.DefaultTimeZoneKey, CurrentTimezoneProvider.TimeZone);
+        }
     }
 
     protected virtual StringSegment RemoveQuotes(StringSegment input)

framework/src/Volo.Abp.Timing/Volo/Abp/Timing/ITimezoneProvider.cs

@@ -14,4 +14,8 @@ public interface ITimezoneProvider
     string IanaToWindows(string ianaTimeZoneName);
 
     TimeZoneInfo GetTimeZoneInfo(string windowsOrIanaTimeZoneId);
+
+    string GetCurrentWindowsTimezoneName();
+
+    string GetCurrentIanaTimezoneName();
 }

framework/src/Volo.Abp.Timing/Volo/Abp/Timing/TZConvertTimezoneProvider.cs

@@ -32,4 +32,15 @@ public class TZConvertTimezoneProvider : ITimezoneProvider, ITransientDependency
     {
         return TZConvert.GetTimeZoneInfo(windowsOrIanaTimeZoneId);
     }
+
+    public virtual string GetCurrentWindowsTimezoneName()
+    {
+        return TimeZoneInfo.Local.StandardName;;
+    }
+
+    public virtual string GetCurrentIanaTimezoneName()
+    {
+        var timezone = GetCurrentWindowsTimezoneName();
+        return TZConvert.WindowsToIana(timezone);
+    }
 }

framework/src/Volo.Abp.Timing/Volo/Abp/Timing/TimingSettingProvider.cs

@@ -10,7 +10,7 @@ public class TimingSettingProvider : SettingDefinitionProvider
     {
         context.Add(
             new SettingDefinition(TimingSettingNames.TimeZone,
-                "UTC",
+                "",
                 L("DisplayName:Abp.Timing.Timezone"),
                 L("Description:Abp.Timing.Timezone"),
                 isVisibleToClients: true)

framework/test/Volo.Abp.AspNetCore.Mvc.Tests/Volo/Abp/AspNetCore/Mvc/Timing/AbpTimeZoneMiddleware_Tests.cs

@@ -18,11 +18,13 @@ namespace Volo.Abp.AspNetCore.Mvc.Timing;
 public class AbpTimeZoneMiddleware_Tests : AspNetCoreMvcTestBase
 {
     private readonly ICurrentTimezoneProvider _currentTimezoneProvider;
+    private readonly ITimezoneProvider _timezoneProvider;
     private readonly FakeUserClaims _fakeRequiredService;
 
     public AbpTimeZoneMiddleware_Tests()
     {
         _currentTimezoneProvider = GetRequiredService<ICurrentTimezoneProvider>();
+        _timezoneProvider = GetRequiredService<ITimezoneProvider>();
         _fakeRequiredService = GetRequiredService<FakeUserClaims>();
     }
 
@@ -40,7 +42,7 @@ public class AbpTimeZoneMiddleware_Tests : AspNetCoreMvcTestBase
         using (_currentTimezoneProvider.Change("UTC"))
         {
             var result = await Client.GetStringAsync("api/timing-test");
-            result.ShouldBe("UTC");
+            result.ShouldBe(_timezoneProvider.GetCurrentIanaTimezoneName());
         }
 
         // Query string
@@ -87,14 +89,15 @@ public class AbpTimeZoneMiddleware_Tests : AspNetCoreMvcTestBase
         using (_currentTimezoneProvider.Change("Europe/Berlin"))
         {
             var result = await Client.GetStringAsync("api/timing-test");
-            result.ShouldBe("UTC");
+
+            result.ShouldBe(_timezoneProvider.GetCurrentIanaTimezoneName());
         }
 
         // Query string
         using (_currentTimezoneProvider.Change("Europe/Berlin"))
         {
             var result = await Client.GetStringAsync("api/timing-test?__timezone=Europe/Istanbul");
-            result.ShouldBe("UTC");
+            result.ShouldBe(_timezoneProvider.GetCurrentIanaTimezoneName());
         }
 
         // Header