fix(iam): return real role data — description, isSystemRole, createdAt, userCount

- IamServiceContext: add EF column mappings for ApplicationRole private
  fields (description, is_system_role, created_at) matching new DB columns
- GetRolesQueryHandler: JOIN with UserRoles to compute real user count
  per role instead of returning 0
- RoleDto/RoleResponse: add UserCount field
- DB: added columns description, is_system_role, created_at to roles table
  with correct data for all 8 roles

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

services/iam-service-net/src/IamService.API/Application/Queries/Roles/GetRolesQuery.cs

@@ -31,4 +31,5 @@ public record RoleDto(
     string Name,
     string? Description,
     bool IsSystemRole,
-    DateTime CreatedAt);
+    DateTime CreatedAt,
+    int UserCount = 0);

services/iam-service-net/src/IamService.API/Application/Queries/Roles/GetRolesQueryHandler.cs

@@ -2,23 +2,27 @@ using MediatR;
 using Microsoft.AspNetCore.Identity;
 using Microsoft.EntityFrameworkCore;
 using IamService.Domain.AggregatesModel.RoleAggregate;
+using IamService.Infrastructure;
 
 namespace IamService.API.Application.Queries.Roles;
 
 /// <summary>
-/// EN: Handler for GetRolesQuery.
-/// VI: Handler cho GetRolesQuery.
+/// EN: Handler for GetRolesQuery — includes user count per role via DB join.
+/// VI: Handler cho GetRolesQuery — bao gồm số user mỗi role qua DB join.
 /// </summary>
 public class GetRolesQueryHandler : IRequestHandler<GetRolesQuery, GetRolesQueryResult>
 {
     private readonly RoleManager<ApplicationRole> _roleManager;
+    private readonly IamServiceContext _dbContext;
     private readonly ILogger<GetRolesQueryHandler> _logger;
 
     public GetRolesQueryHandler(
         RoleManager<ApplicationRole> roleManager,
+        IamServiceContext dbContext,
         ILogger<GetRolesQueryHandler> logger)
     {
         _roleManager = roleManager;
+        _dbContext = dbContext;
         _logger = logger;
     }
 
@@ -27,19 +31,25 @@ public class GetRolesQueryHandler : IRequestHandler<GetRolesQuery, GetRolesQuery
         _logger.LogInformation("Getting roles - Page: {Page}, Size: {Size}", request.PageNumber, request.PageSize);
 
         var query = _roleManager.Roles;
-
         var totalCount = await query.CountAsync(cancellationToken);
 
+        // EN: Join with UserRoles to get user count per role
+        // VI: Join với UserRoles để lấy số user mỗi role
         var roles = await query
             .OrderBy(r => r.Name)
             .Skip((request.PageNumber - 1) * request.PageSize)
             .Take(request.PageSize)
-            .Select(r => new RoleDto(
-                r.Id,
-                r.Name!,
-                r.Description,
-                r.IsSystemRole,
-                r.CreatedAt))
+            .GroupJoin(
+                _dbContext.UserRoles,
+                role => role.Id,
+                userRole => userRole.RoleId,
+                (role, userRoles) => new RoleDto(
+                    role.Id,
+                    role.Name!,
+                    role.Description,
+                    role.IsSystemRole,
+                    role.CreatedAt,
+                    userRoles.Count()))
             .ToListAsync(cancellationToken);
 
         return new GetRolesQueryResult(

services/iam-service-net/src/IamService.API/Controllers/RolesController.cs

@@ -67,7 +67,8 @@ public class RolesController : ControllerBase
                 Name = r.Name,
                 Description = r.Description,
                 IsSystemRole = r.IsSystemRole,
-                CreatedAt = r.CreatedAt
+                CreatedAt = r.CreatedAt,
+                UserCount = r.UserCount
             }),
             Pagination = new PaginationInfo
             {
@@ -435,6 +436,12 @@ public class RoleResponse
     /// VI: Thời gian tạo.
     /// </summary>
     public DateTime CreatedAt { get; set; }
+
+    /// <summary>
+    /// EN: Number of users assigned this role.
+    /// VI: Số lượng người dùng được gán role này.
+    /// </summary>
+    public int UserCount { get; set; }
 }
 
 #endregion

services/iam-service-net/src/IamService.Infrastructure/IamServiceContext.cs

@@ -196,7 +196,17 @@ public class IamServiceContext : IdentityDbContext<ApplicationUser, ApplicationR
             b.Ignore(u => u.LastLoginAt);
             b.Ignore(u => u.DomainEvents);
         });
-        modelBuilder.Entity<ApplicationRole>().ToTable("roles");
+        modelBuilder.Entity<ApplicationRole>(b =>
+        {
+            b.ToTable("roles");
+            b.Property<string>("_description").HasColumnName("description");
+            b.Property<bool>("_isSystemRole").HasColumnName("is_system_role");
+            b.Property<DateTime>("_createdAt").HasColumnName("created_at");
+            b.Ignore(r => r.Description);
+            b.Ignore(r => r.IsSystemRole);
+            b.Ignore(r => r.CreatedAt);
+            b.Ignore(r => r.DomainEvents);
+        });
         modelBuilder.Entity<IdentityUserRole<Guid>>().ToTable("user_roles");
         modelBuilder.Entity<IdentityUserClaim<Guid>>().ToTable("user_claims");
         modelBuilder.Entity<IdentityUserLogin<Guid>>().ToTable("user_logins");