I've seen examples of implementing ASP.NET Identity with an existing SQL database with no Identity tables.. But my question is how to implement ASP.NET Identity in a Blazor application with an existing SQL database that has Identity tables ALREADY implemented.
Is it as simple as just modifying the ApplicationUser model to meet the AspNetUsers table scheme? Or is there more to this way of implementing?
Blazor application is from scratch, wasm and ASP.NET Core Hosted.
Before you run the first time a new Blazor application with Identity (with individual user accounts) you must create an initial database migration, and run it on the target database.
If you look at the migration code, there are an Up and a Down methods that create (Up method) and delete (Down method) the Identity tables in the database.
After adding the migration, but before applying it to the target database, you can edit the .cs migration file, deleting or commenting code, so the migration doesn't create the tables but uses the already created ones. Leave the "insert into __migrations" sentence in the file, because this inserted row is what EF Core uses to test if the application current migration is aligned with the last migration applied to the database.
Of course, your model and existing database tables must be compatible. If you have made changes to the user model or any other identity aspects (change key types, for example), this approach could not be valid. In those cases you could rename the already existing tables, let the standard migration create the new tables, and then use an SQL script to migrate the users, roles, claims and other identity info from old tables to the new ones.
