EF Core 2.0 多对多关系

Question

我正在尝试让我的多对多关系在我的应用程序中发挥作用。

我的模型：

public class BaseEntity
{
    [Key, Required]
    public Guid Id { get; set; }

    public DateTime Created { get; set; }

    #region reference
    public Guid CreatedBy { get; set; }
    #endregion

    public BaseEntity()
    {
        Id = Guid.NewGuid();
        Created = DateTime.Now;
    }
}

public class Person : BaseEntity
{
    /// <summary>
    /// Firstname of the person. Required
    /// </summary>
    [Required]
    public string FirstName { get; set; }

    /// <summary>
    /// Middlename of the contact person. Not required
    /// </summary>
    public string MiddleName { get; set; }

    /// <summary>
    /// Lastname of the contact person. Required
    /// </summary>
    [Required]
    public string LastName { get; set; }

    public Gender Gender { get; set; }

    [NotMapped]
    public string FullName
    {
        get
        {
            StringBuilder sb = new StringBuilder();

            sb.Append(FirstName);
            if (!string.IsNullOrEmpty(MiddleName))
                sb.Append($" {MiddleName}");
            sb.Append($" {LastName}");

            return sb.ToString().TrimEnd(' ');
        }
    }
}

public class User : Person
{
    #region public properties
    [Required]
    public string UserName { get; set; }
    [Required]
    public string Email { get; set; }
    [Required]
    public byte[] Password { get; private set; }
    public byte[] Salt { get; set; }
    public int WorkFactor { get; set; }

    public virtual ICollection<UserRole> UserRoles { get; set; }

    #endregion

    #region constructor

    public User() : base()
    {
        //security settings
        Salt = SecurityHelper.GenerateSalt(12);
        WorkFactor = 5;
        UserRoles = new List<UserRole>();
    }
    #endregion

    #region public methods

    public void SetPassword(string password)
    {
        Password = SecurityHelper.GenerateHash(Encoding.UTF8.GetBytes(password), Salt, WorkFactor, 128);
    }
    #endregion

    public bool ComparePassword(string password)
    {
        return StructuralComparisons.StructuralEqualityComparer.Equals(Password, SecurityHelper.GenerateHash(Encoding.UTF8.GetBytes(password), Salt, WorkFactor, 128));
    }
}

public class Role : BaseEntity
{
    #region public properties
    [Required]
    public string ReadableId { get; set; }
    [Required]
    public string Name { get; set; }
    public string Description { get; set; }

    public virtual ICollection<SecurityPrivilege> Privileges { get; set; } = new List<SecurityPrivilege>();
    public virtual ICollection<UserRole> UserRoles { get; set; }

    #endregion

    #region constructor

    public Role() : base()
    {
        UserRoles = new List<UserRole>();
    }
    #endregion
}

public class UserRole
{
    public Guid UserId { get; set; }
    public Guid RoleId { get; set; }

    [ForeignKey("UserId")]
    public User User { get; set; }
    [ForeignKey("RoleId")]
    public Role Role { get; set; }
}

现在，我想要完成的是，用户能够属于任意数量的角色。

在我的播种器中，我将记录添加到用户的 UserRoles 列表中，只要将数据存储在表中即可。

当我在控制器中（在 API 中）查询时，我无法再次检索此数据：

                var user = _context.Users.Include(x => x.UserRoles).FirstOrDefault(u => u.UserName == request.UserName);

这里，UserRoles 列表总是空的，即使我可以在表格中看到，我应该有行，因为 UserId 字段与 User 对象匹配。

上下文定义：

public class TMContext : DbContext
{
    public TMContext(DbContextOptions<TMContext> options) : base(options)
    {

    }

    #region system sets
    public DbSet<ServerSetting> Settings { get; set; }
    public DbSet<User> Users { get; set; }
    public DbSet<Role> Roles { get; set; }
    public DbSet<SecurityItem> SecurityItems { get; set; }
    public DbSet<UserSession> UserSessions { get; set; }
    public DbSet<SecurityRight> SecurityRights { get; set; }
    public DbSet<SecurityOrgGroup> SecurityOrgGroups { get; set; }
    public DbSet<SecurityPrivilege> Privileges { get; set; }
    #endregion

    #region Core sets
    public DbSet<Tournament> Tournaments { get; set; }
    public DbSet<TournamentSetting> TournamentSettings { get; set; }
    public DbSet<Club> Clubs { get; set; }
    public DbSet<Team> Teams { get; set; }
    public DbSet<TournamentClass> Classes { get; set; }
    public DbSet<Group> Groups { get; set; }
    public DbSet<MatchSet> MatchSets { get; set; }
    #endregion

    #region global sets
    public DbSet<GeoPoint> GeoPositions { get; set; }
    public DbSet<Country> Countries { get; set; }
    #endregion

    protected override void OnModelCreating(ModelBuilder builder)
    {
        base.OnModelCreating(builder);

        builder.Entity<UserRole>()
            .HasKey(t => new { t.UserId, t.RoleId });

        builder.Entity<UserRole>()
            .HasOne(ur => ur.User)
            .WithMany(l => l.UserRoles)
            .HasForeignKey(ur => ur.UserId);

        builder.Entity<UserRole>()
            .HasOne(ur => ur.Role)
            .WithMany(l => l.UserRoles)
            .HasForeignKey(ur => ur.RoleId);

        builder.Entity<ItemRight>()
            .HasKey(t => new {t.SecurityItemId, t.SecurityRightId});

    }
}

我的播种机代码：

public static class DbContextExtension
{

    public static bool AllMigrationsApplied(this DbContext context)
    {
        var applied = context.GetService<IHistoryRepository>()
            .GetAppliedMigrations()
            .Select(m => m.MigrationId);

        var total = context.GetService<IMigrationsAssembly>()
            .Migrations
            .Select(m => m.Key);

        return !total.Except(applied).Any();
    }

    public static void EnsureSeeded(this TMContext context)
    {
        #region users
        //add admin user
        if (!context.Users.Any())
        {
            User admin = new User
            {
                UserName = "admin",
                FirstName = "Admin",
                LastName = "User",
                Email = "mail@email.org",
            };
            admin.CreatedBy = admin.Id;
            admin.SetPassword("admin");
            context.Users.Add(admin);
            context.SaveChanges();
        }
        Guid adminId = context.Users.First(x => x.UserName == "admin").Id;
        #endregion

        #region server settings
        //server settings
        if (!context.Settings.Any())
        {
            context.Settings.Add(new ServerSetting
            {
                Key = "ServerType",
                Section = "Public",
                SortOrder = 0,
                TargetDataType = "System.String",
                Value = "TMLocalServer"
            });
            context.Settings.Add(new ServerSetting
            {
                Key = "Instance",
                Section = "Public",
                SortOrder = 1,
                TargetDataType = "System.Guid",
                Value = Guid.NewGuid().ToString()
            });
            context.SaveChanges();
        }
        #endregion

        #region security rights
        //security rights
        if (!context.SecurityRights.Any())
        {
            context.SecurityRights.Add(new SecurityRight { Name = "Read", CreatedBy = adminId });
            context.SecurityRights.Add(new SecurityRight { Name = "Insert", CreatedBy = adminId });
            context.SecurityRights.Add(new SecurityRight { Name = "Update", CreatedBy = adminId });
            context.SecurityRights.Add(new SecurityRight { Name = "Delete", CreatedBy = adminId });
            context.SaveChanges();
        }
        #endregion

        #region org groups
        //org groups
        if (!context.SecurityOrgGroups.Any())
        {
            #region security groups

            context.SecurityOrgGroups.Add(new SecurityOrgGroup
            {
                ReadableId = "SecurityManagement",
                ParentId = null,
                Text = "Security Management",
                Description = "All seetings concerning basic security",
                CreatedBy = adminId
            });
            context.SaveChanges();
            #endregion

            context.SecurityOrgGroups.Add(new SecurityOrgGroup
            {
                ReadableId = "MasterFiles",
                ParentId = null,
                Text = "Master Files",
                Description = "Management of the Master Files for the application",
                CreatedBy = adminId
            });

            #region operations
            context.SecurityOrgGroups.Add(new SecurityOrgGroup
            {
                ReadableId = "Operations",
                ParentId = null,
                Text = "Operations",
                Description = "Security settings for operations functions",
                CreatedBy = adminId
            });
            context.SaveChanges();
            #endregion
        }
        #endregion

        #region security items
        //security items
        if (!context.SecurityItems.Any())
        {
            SecurityItem item = new SecurityItem { ReadableId = "UserManagement", Name = "User Management", Description = "User management and role membership", CreatedBy = adminId };
            AddItemToGroup(context, "SecurityManagement", item);
            AddAvailableRights(context, item, new List<string> { "Read", "Insert", "Update", "Delete" });
            context.SecurityItems.Add(item);

            item = new SecurityItem { ReadableId = "RoleManagement", Name = "Role Management", Description = "Manage roles and their configuration", CreatedBy = adminId };
            AddItemToGroup(context, "SecurityManagement", item);
            AddAvailableRights(context, item, new List<string> { "Read", "Insert", "Update", "Delete" });
            context.SecurityItems.Add(item);
            context.SaveChanges();

            item = new SecurityItem { ReadableId = "CountryManagement", Name = "Country Management", Description = "Manage list of countries", CreatedBy = adminId };
            AddItemToGroup(context, "MasterFiles", item);
            AddAvailableRights(context, item, new List<string> { "Read", "Insert", "Update", "Delete" });
            context.SecurityItems.Add(item);
            context.SaveChanges();

        }
        #endregion

        #region security roles
        //security roles
        if (!context.Roles.Any())
        {
            context.Roles.Add(new Role
            {
                ReadableId = "SysAdmin",
                Name = "System Administrator",
                Description = "Users can do everything",
                CreatedBy = adminId
            });
            context.SaveChanges();

            AddUserToRoles(context, "admin", new List<string> { "SysAdmin" });
            AddPrivilegesToRole(context, "SysAdmin", "UserManagement", new List<string> { "Read", "Insert", "Update", "Delete" });
            AddPrivilegesToRole(context, "SysAdmin", "RoleManagement", new List<string> { "Read", "Insert", "Update", "Delete" });
            AddPrivilegesToRole(context, "SysAdmin", "CountryManagement", new List<string> { "Read", "Insert", "Update", "Delete" });
            context.SaveChanges();
        }
        #endregion


    }

    #region security helpers

    private static void AddAvailableRights(TMContext dbcontext, SecurityItem item, List<string> rights)
    {
        foreach (string right in rights)
        {
            var r = dbcontext.SecurityRights.FirstOrDefault(x => x.Name == right);
            if (r != null)
            {
                ItemRight ir = new ItemRight { SecurityItemId = item.Id, SecurityRightId = r.Id };
                item.ItemRights.Add(ir);
            }
        }
    }

    private static void AddPrivilegesToRole(TMContext dbcontext, string roleid, string itemid, List<string> rights)
    {
        SecurityItem item = dbcontext.SecurityItems.FirstOrDefault(x => x.ReadableId == itemid);
        Role role = dbcontext.Roles.FirstOrDefault(x => x.ReadableId == roleid);
        if (item != null && role != null)
            foreach (string right in rights)
            {
                var r = dbcontext.SecurityRights.FirstOrDefault(x => x.Name == right);
                if (r != null)
                {
                    SecurityPrivilege privilege = new SecurityPrivilege { CreatedBy = item.CreatedBy, SecurityItemId = item.Id, SecurityRightId = r.Id, RoleId = role.Id, SortOrder = rights.IndexOf(right)};
                    role.Privileges.Add(privilege);
                }
            }
    }

    private static void AddItemToGroup(TMContext dbcontext, string groupid, SecurityItem item)
    {
        SecurityOrgGroup group = dbcontext.SecurityOrgGroups.FirstOrDefault(x => x.ReadableId == groupid);
        if (group != null)
            item.OrgGroupId = group.Id;
    }

    private static void AddOrgGroupToParent(TMContext dbcontext, string parentid, SecurityOrgGroup newgroup)
    {
        SecurityOrgGroup parent = dbcontext.SecurityOrgGroups.FirstOrDefault(x => x.ReadableId == parentid);
        if (parent != null)
        {
            newgroup.ParentId = parent.Id;
            dbcontext.SecurityOrgGroups.Add(newgroup);
        }
    }

    private static void AddUserToRoles(TMContext dbcontext, string username, List<string> roles)
    {
        User user = dbcontext.Users.FirstOrDefault(x => x.UserName == username);
        if (user != null)
        {
            foreach (string readablerole in roles)
            {
                Role role = dbcontext.Roles.FirstOrDefault(x => x.ReadableId == readablerole);
                if (role != null)
                    user.UserRoles.Add(new UserRole { User = user, Role = role });
            }
        }
    }

    private static void AssignRightsToItem()
    {

    }
    #endregion
}

Answer 1

我真的看不出您的代码中有任何错误。可能是播种时出现问题，或者 request.UserName 包含不存在的用户名。

如果您考虑以下种子代码（在某种程度上适合您的实体）：

var users = new User[]
{
    new User{ Id = Guid.NewGuid(), FirstName= "Bob", LastName ="b", UserName = "bob" },
    new User{ Id = Guid.NewGuid(), FirstName= "Alice", LastName ="a", UserName = "alice" }
};

var roles = new Role[]
{
    new Role{ Id = Guid.NewGuid(), CreatedBy = users[0].Id, Name = "role1", ReadableId="role1" },
    new Role{ Id = Guid.NewGuid(), CreatedBy = users[0].Id, Name = "role2", ReadableId="role2" }
};

_context.Users.AddRange(users);
_context.Roles.AddRange(roles);
_context.SaveChanges();

var userroles = new UserRole[]
{
    new UserRole{ User = users[0], Role = roles[0] }, 
    new UserRole{ User = users[0], Role = roles[1] }, //bob is assigned 2 roles
    new UserRole{ User = users[1], Role = roles[1] }, 
};

然后你调用以下方法：

var user = _context.Users.Include(x => x.UserRoles).FirstOrDefault(u => u.UserName == "bob");

那么用户将包含 2 个用户角色。在观察窗口中验证：

== 编辑 ==

您说您的 UserRoles 的 Role 属性等于 null。您需要使用ThenInclude() 扩展方法来包含这些内容。此方法允许您包含更深几个级别的导航属性，如下所示：

var user = _context.Users
        .Include(u => u.UserRoles)
        .ThenInclude(ur => ur.Role)
        .FirstOrDefault(u => u.UserName == "bob");