Logged user based connection string in .NET Core

Question

I have an application that uses identity database to store users and customers.

Each customer has also a separate database with its data and its connection string is stored in Customer table in the identity database.

AspNetUsers has a field to tell which customer the user belongs to (also identity db).

I want to assign connection string to the user when he logs in and make it available in the application for the duration of the session.

I currently have customer model:

public partial class `Customer`
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int NoLicenses { get; set; }
    public bool? Enabled { get; set; }
    public string CustomerConnectionString { get; set; }
}

and user model:

public class ApplicationUser : IdentityUser
{
    public string CustomerId { get; set; }

    public bool? IsEnabled { get; set; }

    // there ideally I'd have a connstring property
}

The models map db table fields.

I'm using .NET Core 1.1 and EF Core.

Answer 1

With the defalut ASP.NET Identity template , you can :

1. extend the ApplicationUser class in Models folder :

   public class ApplicationUser : IdentityUser
   {
       public string CustomerId { get; set; }
   
       public bool? IsEnabled { get; set; }
   
       //add your custom claims
       public string CustomerConnectionString { get; set; }
   }
   

2. Add your custom model to ApplicationDbContext in Data folder :

   public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
   {
       public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
           : base(options)
       {
       }
   
       protected override void OnModelCreating(ModelBuilder builder)
       {
           base.OnModelCreating(builder);
           // Customize the ASP.NET Identity model and override the defaults if needed.
           // For example, you can rename the ASP.NET Identity table names and more.
           // Add your customizations after calling base.OnModelCreating(builder);
   
   
       }
   
       public DbSet<Customer> Customers { get; set; }
   }
   

3. Sync your database : Add-Migration xxxx , then run the Update-Database command in Package Manager Console . Now you have the Customer table and have CustomerConnectionString column in AspNetUsers table.

4. Create you own implementation of IUserClaimsPrincipalFactory by inheriting the default one to generate a ClaimsPrincipal from your user :

   public class AppClaimsPrincipalFactory : UserClaimsPrincipalFactory<ApplicationUser, IdentityRole>
   {
       public AppClaimsPrincipalFactory(
         UserManager<ApplicationUser> userManager
         , RoleManager<IdentityRole> roleManager
         , IOptions<IdentityOptions> optionsAccessor)
       : base(userManager, roleManager, optionsAccessor)
       { }
   
       public async override Task<ClaimsPrincipal> CreateAsync(ApplicationUser user)
       {
           var principal = await base.CreateAsync(user);
   
           if (!string.IsNullOrWhiteSpace(user.CustomerId))
           {
   
               ((ClaimsIdentity)principal.Identity).AddClaims(new[] {
               new Claim("customid", user.CustomerId)
               });
           }
   
           if (!string.IsNullOrWhiteSpace(user.CustomerConnectionString))
           {
   
               ((ClaimsIdentity)principal.Identity).AddClaims(new[] {
               new Claim("CustomerConnectionString", user.CustomerConnectionString)
               });
           }
           return principal;
       }
   }
   

5. Register the custom factory you just created in your application startup class, after adding Identity service:

   // Add framework services.
   services.AddDbContext<ApplicationDbContext>(options =>
           options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));
   
   services.AddIdentity<ApplicationUser, IdentityRole>()
           .AddEntityFrameworkStores<ApplicationDbContext>()
           .AddDefaultTokenProviders();
   
     services.AddScoped<Microsoft.AspNetCore.Identity.IUserClaimsPrincipalFactory<ApplicationUser>, AppClaimsPrincipalFactory>();
   

6. Then you could access the claims like :

   var connectString = User.Claims.FirstOrDefault(c => c.Type == "CustomerConnectionString").Value;
   

7. Modify the creating/editing user view/controller , add the customer dropdownlist on view , get the custom id in Register function in AccountController , query the connectingString of custom from db , and save in ApplicationUser object :

    var user = new ApplicationUser { UserName = model.Email, Email = model.Email };
    var result = await _userManager.CreateAsync(user, model.Password);