使用EF6简实现多租户的应用

什么是多租户

网上有好多解释，有些上升到了架构设计，让你觉得似乎非常高深莫测，特别是目前流行的ABP架构中就有提到多租户（IMustHaveTenant），其实说的简单一点就是再每一张数据库的表中添加一个TenantId的字段，用于区分属于不同的租户（或是说不同的用户组）的数据。关键是现实的方式必须对开发人员来说是透明的，不需要关注这个字段的信息，由后台或是封装在基类中实现数据的筛选和更新。

基本原理

从新用户注册时就必须指定用户的TenantId,我的例子是用CompanyId,公司信息做为TenantId,哪些用户属于不同的公司，每个用户将来只能修改和查询属于本公司的数据。

接下来就是用户登录的时候获取用户信息的时候把TenantId保存起来，asp.net mvc（不是 core） 是通过 Identity 2.0实现的认证和授权，这里需要重写部分代码来实现。

最后用户对数据查询/修改/新增时把用户信息中TenantId，这里就需要设定一个Filter(过滤器)和每次SaveChange的插入TenantId

如何实现

第一步，扩展 Asp.net Identity user 属性，必须新增一个TenantId字段,根据Asp.net Mvc 自带的项目模板修改IdentityModels.cs 这个文件

   // You can add profile data for the user by adding more properties to your ApplicationUser class, please visit http://go.microsoft.com/fwlink/?LinkID=317594 to learn more.
   public class ApplicationUser : IdentityUser
   {
     public async Task<ClaimsIdentity> GenerateUserIdentityAsync(UserManager<ApplicationUser> manager, string authenticationType)
     {
       // Note the authenticationType must match the one defined in CookieAuthenticationOptions.AuthenticationType
       var userIdentity = await manager.CreateIdentityAsync(this, authenticationType);
       // Add custom user claims here
       userIdentity.AddClaim(new Claim("http://schemas.microsoft.com/identity/claims/tenantid", this.TenantId.ToString()));
       userIdentity.AddClaim(new Claim("CompanyName", this.CompanyName));
       userIdentity.AddClaim(new Claim("EnabledChat", this.EnabledChat.ToString()));
       userIdentity.AddClaim(new Claim("FullName", this.FullName));
       userIdentity.AddClaim(new Claim("AvatarsX50", this.AvatarsX50));
       userIdentity.AddClaim(new Claim("AvatarsX120", this.AvatarsX120));
       return userIdentity;
     }
     public async Task<ClaimsIdentity> GenerateUserIdentityAsync(UserManager<ApplicationUser> manager)
     {
       // Note the authenticationType must match the one defined in CookieAuthenticationOptions.AuthenticationType
       var userIdentity = await manager.CreateIdentityAsync(this, DefaultAuthenticationTypes.ApplicationCookie);
       // Add custom user claims here
       return userIdentity;
     }

     [Display(Name = "全名")]
     public string FullName { get; set; }
     [Display(Name = "性别")]
     public int Gender { get; set; }
     public int AccountType { get; set; }
     [Display(Name = "所属公司")]
     public string CompanyCode { get; set; }
     [Display(Name = "公司名称")]
     public string CompanyName { get; set; }
     [Display(Name = "是否在线")]
     public bool IsOnline { get; set; }
     [Display(Name = "是否开启聊天功能")]
     public bool EnabledChat { get; set; }
     [Display(Name = "小头像")]
     public string AvatarsX50 { get; set; }
     [Display(Name = "大头像")]
     public string AvatarsX120 { get; set; }
     [Display(Name = "租户ID")]
     public int TenantId { get; set; }
   }

   public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
   {
     public ApplicationDbContext()
         : base("DefaultConnection", throwIfV1Schema: false) => Database.SetInitializer<ApplicationDbContext>(null);

     public static ApplicationDbContext Create() => new ApplicationDbContext();

   }

　　第二步 修改注册用户的代码，注册新用户的时候需要选择所属的公司信息

  [HttpPost]
     [AllowAnonymous]
     [ValidateAntiForgeryToken]
     public async Task<ActionResult> Register(AccountRegistrationModel viewModel)
     {
       var data = this._companyService.Queryable().Select(x => new ListItem() { Value = x.Id.ToString(), Text = x.Name });
       this.ViewBag.companylist = data;

       // Ensure we have a valid viewModel to work with
       if (!this.ModelState.IsValid)
       {
         return this.View(viewModel);
       }

       // Try to create a user with the given identity
       try
       {
         // Prepare the identity with the provided information
         var user = new ApplicationUser
         {
           UserName = viewModel.Username,
           FullName = viewModel.Lastname + "." + viewModel.Firstname,
           CompanyCode = viewModel.CompanyCode,
           CompanyName = viewModel.CompanyName,
           TenantId=viewModel.TenantId,
           Email = viewModel.Email,
           AccountType = 

         };
         var result = await this.UserManager.CreateAsync(user, viewModel.Password);

         // If the user could not be created
         if (!result.Succeeded)
         {
           // Add all errors to the page so they can be used to display what went wrong
           this.AddErrors(result);

           return this.View(viewModel);
         }

         // If the user was able to be created we can sign it in immediately
         // Note: Consider using the email verification proces
         await this.SignInAsync(user, true);

         return this.RedirectToLocal();
       }
       catch (DbEntityValidationException ex)
       {
         // Add all errors to the page so they can be used to display what went wrong
         this.AddErrors(ex);

         return this.View(viewModel);
       }
     }

AccountController.cs

第三步 读取登录用户的TenantId 在用户查询和新增修改时把TenantId插入到表中,这里需要引用

Z.EntityFramework.Plus，这个是免费开源的一个类库，功能强大

  public StoreContext()
         : base("Name=DefaultConnection") {
       //获取登录用户信息,tenantid
       var claimsidentity = (ClaimsIdentity)HttpContext.Current.User.Identity;
       var tenantclaim = claimsidentity?.FindFirst("http://schemas.microsoft.com/identity/claims/tenantid");
       var tenantid = Convert.ToInt32(tenantclaim?.Value);
       //设置当对Work对象进行查询时默认添加过滤条件
       QueryFilterManager.Filter<Work>(q => q.Where(x => x.TenantId == tenantid));
       //设置当对Order对象进行查询时默认添加过滤条件
       QueryFilterManager.Filter<Order>(q => q.Where(x => x.TenantId == tenantid));
     }

  public override Task<int> SaveChangesAsync(CancellationToken cancellationToken)
     {
       var currentDateTime = DateTime.Now;
       var claimsidentity = (ClaimsIdentity)HttpContext.Current.User.Identity;
       var tenantclaim = claimsidentity?.FindFirst("http://schemas.microsoft.com/identity/claims/tenantid");
       var tenantid = Convert.ToInt32(tenantclaim?.Value);
       foreach (var auditableEntity in this.ChangeTracker.Entries<Entity>())
       {
         if (auditableEntity.State == EntityState.Added || auditableEntity.State == EntityState.Modified)
         {
           //auditableEntity.Entity.LastModifiedDate = currentDateTime;
           switch (auditableEntity.State)
           {
             case EntityState.Added:
               auditableEntity.Property("LastModifiedDate").IsModified = false;
               auditableEntity.Property("LastModifiedBy").IsModified = false;
               auditableEntity.Entity.CreatedDate = currentDateTime;
               auditableEntity.Entity.CreatedBy = claimsidentity.Name;
               auditableEntity.Entity.TenantId = tenantid;
               break;
             case EntityState.Modified:
               auditableEntity.Property("CreatedDate").IsModified = false;
               auditableEntity.Property("CreatedBy").IsModified = false;
               auditableEntity.Entity.LastModifiedDate = currentDateTime;
               auditableEntity.Entity.LastModifiedBy = claimsidentity.Name;
               auditableEntity.Entity.TenantId = tenantid;
               //if (auditableEntity.Property(p => p.Created).IsModified || auditableEntity.Property(p => p.CreatedBy).IsModified)
               //{
               //    throw new DbEntityValidationException(string.Format("Attempt to change created audit trails on a modified {0}", auditableEntity.Entity.GetType().FullName));
               //}
               break;
           }
         }
       }
       return base.SaveChangesAsync(cancellationToken);
     }

     public override int SaveChanges()
     {
       var currentDateTime = DateTime.Now;
       var claimsidentity =(ClaimsIdentity)HttpContext.Current.User.Identity;
       var tenantclaim = claimsidentity?.FindFirst("http://schemas.microsoft.com/identity/claims/tenantid");
       var tenantid = Convert.ToInt32(tenantclaim?.Value);
       foreach (var auditableEntity in this.ChangeTracker.Entries<Entity>())
       {
         if (auditableEntity.State == EntityState.Added || auditableEntity.State == EntityState.Modified)
         {
           auditableEntity.Entity.LastModifiedDate = currentDateTime;
           switch (auditableEntity.State)
           {
             case EntityState.Added:
               auditableEntity.Property("LastModifiedDate").IsModified = false;
               auditableEntity.Property("LastModifiedBy").IsModified = false;
               auditableEntity.Entity.CreatedDate = currentDateTime;
               auditableEntity.Entity.CreatedBy = claimsidentity.Name;
               auditableEntity.Entity.TenantId = tenantid;
               break;
             case EntityState.Modified:
               auditableEntity.Property("CreatedDate").IsModified = false;
               auditableEntity.Property("CreatedBy").IsModified = false;
               auditableEntity.Entity.LastModifiedDate = currentDateTime;
               auditableEntity.Entity.LastModifiedBy = claimsidentity.Name;
               auditableEntity.Entity.TenantId = tenantid;
               break;
           }
         }
       }
       return base.SaveChanges();
     }

DbContext.cs

经过以上3步就实现一个简单的多租户查询数据的功能。

希望对大家有用。