利用EF6简单实现多租户的应用

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 = 0

  };
  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。

总结

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