Infrastructure: DatabaseName is only used by tooling and shouldn't be public runtime API

[rigofunc]

Today, I test some ef core features, I assume the test_db1 and test_db2 in the same machine:
step1: I use database named test_db1 in connection string
step2: I change the database name in OnModelCreating(ModelBuilder modelBuilder) method like this:

builder.Model.Relational().DatabaseName = "test_db2";

step3: I check where the data inserted, in test_db1? or in test_db2?

The result is data inserted into test_db1, so, my question is waht's the DatabaseName property of RelationalModelAnnotations used for?

[ajcvickers]

@xyting The database to use is controlled only by the connection string. The DatabaseName is stored in the model as part of the reverse engineering process, but is otherwise not used.

Note for triage: Consider removing sugar API for this annotation if it is only needed by reverse engineering.

[rigofunc]

@ajcvickers Thanks.

[bricelam]

Re-opening so we can discuss @ajcvickers's comment in triage.

[lajones]

Added breaking change tag as we would be removing public API.

[ajcvickers]

Should do this for 2.0, since it is a breaking change.

[lajones]

Fixed with PR #8247.

[rigofunc]

Good job, thanks!

[rigofunc]

@lajones Make it a Scaffolding() one instead is ok if it is only needed by reverse engineering, but, the reason why I test this feature is I want to dynamically change the database name at runtime. That's to say I want support multiple databases/tables sharding (in the same machine, I assume) in the same model. For MySQL, the Schema is the same as database, so for MySQL, I can dynamically change the the Schema to achieve the same purpose. see this implementation

[bricelam]

@xyting Could you just use a new connection string pointing to a different database?

var newConnectionString = new SqlConnectionStringBuilder(oldConnectionString) { InitialCatalog = newDatabase }.ToString();

You may also be looking for #4019

[rigofunc]

@bricelam Yes, this is one choice. Right row, I use a DbContextFactory to dynamic create DbContext to achieve different machine multiple databases/tables sharding in the same model. In the same machine, I do not need to recreate the DbContext, I only change the MySQL Schema to archeve the database change (I doesn't study all the ef core code, so maybe I not know the Model cache whether have any performance issues if I dynamic change the MySQL EntityType's Schema).

OK, the all for test purpose, I haven't use it in my production.