服务器端分页优化

src/Jiaowu.Api/Controllers/UsersController.cs

@@ -1,5 +1,6 @@
 using System.ComponentModel.DataAnnotations;
 using System.Security.Claims;
+using Jiaowu.Api.Contracts;
 using Jiaowu.Api.Domain.Academic;
 using Jiaowu.Api.Domain.Identity;
 using Jiaowu.Api.Infrastructure.Persistence;
@@ -19,10 +20,35 @@ public sealed class UsersController(
     RoleManager<ApplicationRole> roleManager) : ControllerBase
 {
     [HttpGet]
-    public async Task<ActionResult<object>> GetUsers(CancellationToken cancellationToken)
+    public async Task<ActionResult<PagedResult<UserListItem>>> GetUsers(
+        int page = 1,
+        int pageSize = 20,
+        string? keyword = null,
+        CancellationToken cancellationToken = default)
     {
-        var users = await userManager.Users.AsNoTracking()
+        if (page < 1 || pageSize is < 1 or > 100)
+            return ValidationProblem("页码必须大于 0，且每页条数应在 1 至 100 之间。");
+
+        var query = userManager.Users.AsNoTracking();
+        if (!string.IsNullOrWhiteSpace(keyword))
+        {
+            keyword = keyword.Trim();
+            query = query.Where(user =>
+                user.UserName!.Contains(keyword) ||
+                user.DisplayName.Contains(keyword) ||
+                (user.StaffNumber != null && user.StaffNumber.Contains(keyword)) ||
+                (from userRole in db.UserRoles
+                 join role in db.Roles on userRole.RoleId equals role.Id
+                 where userRole.UserId == user.Id && role.Name!.Contains(keyword)
+                 select role.Id).Any());
+        }
+
+        var total = await query.CountAsync(cancellationToken);
+        var users = await query
             .OrderBy(x => x.UserName)
+            .ThenBy(x => x.Id)
+            .Skip((page - 1) * pageSize)
+            .Take(pageSize)
             .Select(x => new
             {
                 x.Id,
@@ -36,26 +62,34 @@ public sealed class UsersController(
             })
             .ToListAsync(cancellationToken);
 
-        var result = new List<object>();
-        foreach (var user in users)
-        {
-            var identityUser = await userManager.FindByIdAsync(user.Id.ToString());
-            result.Add(new
-            {
-                user.Id,
-                user.UserName,
-                user.DisplayName,
-                user.StaffNumber,
-                user.CollegeId,
-                user.IsEnabled,
-                user.LastLoginAt,
-                user.CreatedAt,
-                Roles = identityUser is null
-                    ? []
-                    : await userManager.GetRolesAsync(identityUser)
-            });
-        }
-        return Ok(result);
+        var userIds = users.Select(x => x.Id).ToArray();
+        var roleRows = await (
+            from userRole in db.UserRoles.AsNoTracking()
+            join role in db.Roles.AsNoTracking() on userRole.RoleId equals role.Id
+            where userIds.Contains(userRole.UserId)
+            select new { userRole.UserId, RoleName = role.Name! })
+            .ToListAsync(cancellationToken);
+        var rolesByUser = roleRows
+            .GroupBy(x => x.UserId)
+            .ToDictionary(
+                group => group.Key,
+                group => (IReadOnlyCollection<string>)group
+                    .Select(x => x.RoleName)
+                    .OrderBy(x => x)
+                    .ToArray());
+
+        var items = users.Select(user => new UserListItem(
+            user.Id,
+            user.UserName ?? string.Empty,
+            user.DisplayName,
+            user.StaffNumber,
+            user.CollegeId,
+            user.IsEnabled,
+            user.LastLoginAt,
+            user.CreatedAt,
+            rolesByUser.GetValueOrDefault(user.Id, Array.Empty<string>())))
+            .ToArray();
+        return Ok(new PagedResult<UserListItem>(items, total, page, pageSize));
     }
 
     [HttpGet("roles")]
@@ -281,6 +315,16 @@ public sealed record CreateUserRequest(
     [MinLength(1)] string[] Roles);
 
 public sealed record SetUserStatusRequest(bool IsEnabled);
+public sealed record UserListItem(
+    Guid Id,
+    string UserName,
+    string DisplayName,
+    string? StaffNumber,
+    Guid? CollegeId,
+    bool IsEnabled,
+    DateTime? LastLoginAt,
+    DateTime CreatedAt,
+    IReadOnlyCollection<string> Roles);
 public sealed record SetRolesRequest(
     [MaxLength(30)] string? StaffNumber,
     Guid? CollegeId,