EFCore 连接表和 AutoMapper

Question

我想从我的 ASP.net Identity Users 表中查询所有用户，并将它们映射到一个简单的 DTO，如下所示：

public class UserDto
{
    public string Firstname { get; set; }
    public string Lastname { get; set; }
    public string Email { get; set; }
    public IEnumerable<string> Roles { get; set; }
}

角色列表应该只包含角色的名称，所以我从角色表中加入角色并获取名称。现在我想通过使用 AutoMapper 来简化这个过程，并将结果直接映射到我的 DTO 中。

var users = await _userManager.Users
            .AsNoTracking()
            .Include(u => u.Roles)
            .Select(u => new {
                User = u,
                Roles = u.Roles
                    .Join(_roleManager.Roles, 
                            a => a.RoleId, 
                            b => b.Id, 
                            (a, b) => b.Name)
                    .ToList()
            })
            .ToListAsync();

我正在努力寻找一个很好的解决方案来使用 AutoMapper 将此数据映射到 UserDto 对象列表。我尝试ProjectTo<UserDto>在我的映射器配置中使用并实现表连接，但是我收到了很多 efcore 警告，表明我的查询是在客户端上执行的。

问题：是否有一种简单有效的方法可以使用 AutoMapper 和 efcore 做到这一点？

更新 即使没有 AutoMapper 它也会产生警告:(

var users = await _userManager.Users
            .AsNoTracking()
            .Include(u => u.Roles)
            .Select(u => new UserDto {
                Firstname = u.Firstname,
                Lastname = u.Lastname,
                Email = u.Email,
                Roles = u.Roles
                    .Join(_roleManager.Roles, 
                            a => a.RoleId, 
                            b => b.Id, 
                            (a, b) => b.Name)
                    .ToList()
            })                
            .ToListAsync();

这是 efcore 日志输出：

info: Microsoft.EntityFrameworkCore.Storage.IRelationalCommandBuilderFactory[1]
      Executed DbCommand (2ms) [Parameters=[@__get_Item_0='?' (Size = 450)], CommandType='Text', CommandTimeout='30']
      SELECT TOP(1) [e].[Id], [e].[AccessFailedCount], [e].[Address], [e].[City], [e].[ConcurrencyStamp], [e].[Country], [e].[CustomerIdentifier], [e].[Email], [e].[EmailConfirmed], [e].[Firstname], [e].[Gender], [e].[Lastname], [e].[LockoutEnabled], [e].[LockoutEnd], [e].[NormalizedEmail], [e].[NormalizedUserName], [e].[PasswordHash], [e].[PhoneNumber], [e].[PhoneNumberConfirmed], [e].[Region], [e].[SecurityStamp], [e].[TwoFactorEnabled], [e].[UserName], [e].[ZipCode]
      FROM [AspNetUsers] AS [e]
      WHERE [e].[Id] = @__get_Item_0

info: Microsoft.EntityFrameworkCore.Storage.IRelationalCommandBuilderFactory[1]
      Executed DbCommand (2ms) [Parameters=[@__normalizedRoleName_0='?' (Size = 256)], CommandType='Text', CommandTimeout='30']
      SELECT TOP(2) [r].[Id], [r].[ConcurrencyStamp], [r].[Name], [r].[NormalizedName]
      FROM [AspNetRoles] AS [r]
      WHERE [r].[NormalizedName] = @__normalizedRoleName_0

info: Microsoft.EntityFrameworkCore.Storage.IRelationalCommandBuilderFactory[1]
      Executed DbCommand (6ms) [Parameters=[@__get_Item_0='?' (Size = 450), @__get_Item_1='?' (Size = 450)], CommandType='Text', CommandTimeout='30']
      SELECT TOP(1) [e].[UserId], [e].[RoleId]
      FROM [AspNetUserRoles] AS [e]
      WHERE ([e].[UserId] = @__get_Item_0) AND ([e].[RoleId] = @__get_Item_1)

warn: Microsoft.EntityFrameworkCore.Query.Internal.SqlServerQueryCompilationContextFactory[6]
      The Include operation for navigation: 'u.Roles' was ignored because the target navigation is not reachable in the final query results. To configure this warning use the DbContextOptionsBuilder.ConfigureWarnings API (event id 'CoreEventId.IncludeIgnoredWarning'). ConfigureWarnings can be used when overriding the DbContext.OnConfiguring method or using AddDbContext on the application service provider.

info: Microsoft.EntityFrameworkCore.Storage.IRelationalCommandBuilderFactory[1]
      Executed DbCommand (1ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
      SELECT [u].[Firstname], [u].[Lastname], [u].[Email], [u].[Id]
      FROM [AspNetUsers] AS [u]

info: Microsoft.EntityFrameworkCore.Storage.IRelationalCommandBuilderFactory[1]
      Executed DbCommand (2ms) [Parameters=[@_outer_Id='?' (Size = 450)], CommandType='Text', CommandTimeout='30']
      SELECT [b].[Name]
      FROM [AspNetUserRoles] AS [a]
      INNER JOIN [AspNetRoles] AS [b] ON [a].[RoleId] = [b].[Id]
      WHERE @_outer_Id = [a].[UserId]

info: Microsoft.EntityFrameworkCore.Storage.IRelationalCommandBuilderFactory[1]
      Executed DbCommand (1ms) [Parameters=[@_outer_Id='?' (Size = 450)], CommandType='Text', CommandTimeout='30']
      SELECT [b].[Name]
      FROM [AspNetUserRoles] AS [a]
      INNER JOIN [AspNetRoles] AS [b] ON [a].[RoleId] = [b].[Id]
      WHERE @_outer_Id = [a].[UserId]

更新 2

在警告之后，我刚刚删除了 Include 语句并找到了一个有效的解决方案：

var users = await _userManager.Users
            .AsNoTracking()
            .Select(u => new UserDto {
                Firstname = u.Firstname,
                Lastname = u.Lastname,
                Email = u.Email,
                Roles = u.Roles
                    .Join(_roleManager.Roles, 
                            a => a.RoleId, 
                            b => b.Id, 
                            (a, b) => b.Name)
                    .ToList()
            })                
            .ToListAsync();

Answer 1

我从查询中删除了 Include 语句，将 select 语句移动到我的 AutoMapper 配置文件中，并将角色表作为参数添加到我的 ProjectTo 语句中。现在它按预期工作并且不会产生任何 efcore 警告。

有效查询

        var users = await _userManager.Users
            .AsNoTracking()
            .ProjectTo<UserDto>(new { roles = _roleManager.Roles })              
            .ToListAsync();

自动映射器配置文件

        IQueryable<IdentityRole> roles = null;
        CreateMap<User, UserDto>()
            .ForMember(x => x.Roles, opt => 
                opt.MapFrom(src => 
                    src.Roles
                        .Join(roles, a => a.RoleId, b => b.Id, (a, b) => b.Name)
                        .ToList()
                )
            );