Implement ASP.NET Identity into an existing database

Question

I have an existing project and SQL database with a Users table (let's call it ""MyOldUsersTable") and attached tables (address, phones, positions, etc) with PK-FK relationships.

NB: This database doesn't use either Membership or Identity. It is a database extracted from another project and "MyOldUsersTable" doesn't contain any login info (password, last login, etc...)

I started by using a Web Api project with identity, but it generates the defaults tables (AspNetUsers, AspNetUserRoles, AspNetUserLogins...)

Goal: get ASP.NET Identity to use the existing tables

I tried this solution: How can I change the table names when using Visual Studio 2013 ASP.NET Identity? But Identity renames "MyOldUsersTable" to "MyOldUsersTable1" and Renames the "AspNetUsers" table to "MyOldUsersTable". That wasn't very usefull.

What would be the best way to proceed? I see three options:

Solution 1: Move the "MyOldUsersTable" table fields to the "ASPNETUser" table and change the PK-FK with the other tables
Solution 2: Make Identity understand that the users table is now "MyOldUsersTable"
Solution 3: Keep the two systems and just add a PK-FK between "AspNetUsers" and "MyOldUsersTable"

So....where do the passwords and other data live? It sounds like your scenario would be better served by deploying the "AspNetUsers" table(s) and migrating your data over, and having all users reset their passwords? — Brendan Green
The first system didn't have any login/password. It was just input into the system. But the records in "MyOldUsersTable" are now converted into real accounts. Problem is, "MyOldUsersTable" is not the only table. It has many dependencies PK/FK with other tables. So if I use "AspNetUsers", I will have to recreate all the 10+ table constraints. On top of everything, the PKs of "AspNetUsers" (nvarchar) and "MyOldUsersTable" (int) are different. — Eric Software Engineering
Solution 3. Just add new cross-table between "AspNetUsers" and "MyOldUsersTable". You must obtain which login belongs to concrete user — Hemid Abbasov

Ze French Accent Ze French Accent · Accepted Answer · 2018-07-11T06:13:37

Solution 2: Keep the two systems and just add a PK-FK between "AspNetUsers" and "MyOldUsersTable". Possible, but there can be duplicates in the fields (emails, phone). Also having two users tables to maintain is not ideal.

It works when adding One to Zero to One relationship between the tables like this:

        modelBuilder.Entity<MyOldUsersTable>()
            .HasOptional(e => e.ApplicationUser)
            .WithRequired(e => e.MyOldUsersTable)
            .Map(m => m.MapKey("MyOldUsersTableId"))
            .WillCascadeOnDelete(false);

Best: Solution 3. Make Identity understand that the users table is now "MyOldUsersTable" by removing all the default behaviors coming from the IdentityUser.

First step is to remove the reference to the IdentityDbContext by replacing:

public class ApplicationDbContext : IdentityDbContext<ApplicationUser>

by:

public class ApplicationDbContext : DbContext

Then replace the default UserStore with a custom one:

var manager = new ApplicationUserManager(new UserStore<ApplicationUser>(context.Get<ApplicationDbContext>()));

Replaced by:

var manager = new ApplicationUserManager(new CustomUserStore(context.Get<ApplicationDbContext>()));

Finally, the CustomUserStore is implemented using the interfaces needed. For instance for password, email and security stamp:

public class CustomUserStore : IUserStore<MyOldUsersTable, int>, IUserPasswordStore<MyOldUsersTable, int>, IUserEmailStore<MyOldUsersTable, int>,  IUserSecurityStampStore<MyOldUsersTable, int>

Implement ASP.NET Identity into an existing database

1 Answers