feat: 增加分页排序与FluentValidation

src/Application/TakeoutSaaS.Application/App/Merchants/Handlers/SearchMerchantsQueryHandler.cs

@@ -23,20 +23,44 @@ public sealed class SearchMerchantsQueryHandler(
         var tenantId = _tenantProvider.GetCurrentTenantId();
         var merchants = await _merchantRepository.SearchAsync(tenantId, request.Status, cancellationToken);
 
-        return merchants
-            .Select(merchant => new MerchantDto
-            {
-                Id = merchant.Id,
-                TenantId = merchant.TenantId,
-                BrandName = merchant.BrandName,
-                BrandAlias = merchant.BrandAlias,
-                LogoUrl = merchant.LogoUrl,
-                Category = merchant.Category,
-                ContactPhone = merchant.ContactPhone,
-                ContactEmail = merchant.ContactEmail,
-                Status = merchant.Status,
-                JoinedAt = merchant.JoinedAt
-            })
+        var sorted = ApplySorting(merchants, request.SortBy, request.SortDescending);
+        var paged = sorted
+            .Skip((request.Page - 1) * request.PageSize)
+            .Take(request.PageSize)
             .ToList();
+
+        return paged.Select(merchant => new MerchantDto
+        {
+            Id = merchant.Id,
+            TenantId = merchant.TenantId,
+            BrandName = merchant.BrandName,
+            BrandAlias = merchant.BrandAlias,
+            LogoUrl = merchant.LogoUrl,
+            Category = merchant.Category,
+            ContactPhone = merchant.ContactPhone,
+            ContactEmail = merchant.ContactEmail,
+            Status = merchant.Status,
+            JoinedAt = merchant.JoinedAt,
+            CreatedAt = merchant.CreatedAt
+        }).ToList();
+    }
+
+    private static IOrderedEnumerable<Domain.Merchants.Entities.Merchant> ApplySorting(
+        IReadOnlyCollection<Domain.Merchants.Entities.Merchant> merchants,
+        string? sortBy,
+        bool sortDescending)
+    {
+        return sortBy?.ToLowerInvariant() switch
+        {
+            "brandname" => sortDescending
+                ? merchants.OrderByDescending(x => x.BrandName)
+                : merchants.OrderBy(x => x.BrandName),
+            "status" => sortDescending
+                ? merchants.OrderByDescending(x => x.Status)
+                : merchants.OrderBy(x => x.Status),
+            _ => sortDescending
+                ? merchants.OrderByDescending(x => x.CreatedAt)
+                : merchants.OrderBy(x => x.CreatedAt)
+        };
     }
 }