Associate Table Prefixes with DBs

[Articdive]

Would be an amazing feature if we could give DBs custom Table prefixes (so 1 model has a different table prefix in different DBs e.g. in DB 1: HELLO_USERS and in DB 2: BYE_USERS), I'm currently working on a project and need to convert data from 1 DB to the other, but they have different table prefixes, I currently use a little reflection to make it somewhat possible but I could see this as a useful feature. Let me know if you would like some help with Impl..

[ipolevoy]

Did you find a way to do this ?

[Articdive]

@ipolevoy I managed to use reflection to make it work and loaded it all into memory once (using reflection to change the @ Table annotation for load_prefix) and then changed the model's DB to the save DB also using reflection to change the @ Table (save_prefix) Annotation. Pretty much

• Change into load prefix
• Load into Memory
• Close ActiveJDBC (actively close all connections)
• Change DBName and Table prefix for save
• Reinit ActiveJDBC
  It's a very hacky way around it, I realized (the reason why I close this) is that models are only linked to 1 DB and this feature would therefore be kinda useless for my case. If models could be linked to multiple DBs (I haven't researched ACtiveJDBC enough to know) then it could become a very useful feature.

[ipolevoy]

@Articdive would something like this work for you: https://javalite.io/database_connection_management#multiple-database-example ?

[Articdive]

@ipolevoy unfortuantely that wouldn't work, I really need 1 Model (not 2 different ones) to be saved/loaded in 2 different DBs, I realized however that this does kind off defeat the purpose of ActiveJDBC.

[ipolevoy]

@Articdive actually, you can do this like this:

public class Person extends Model{}

Base.open(driver, url1, user1, password1);
List<Person> people = Person..where(...);
Base.close(); 

Base.open(driver, url2, user2, password2);
for(Person p: people){
   p.set("first_name", "John").saveIt();
}
Base.close(); 

so, what happens here, you read data from one database then modify it and write to another. The model only cares that there is an available default connection.

Will this help?

[Articdive]

This is pretty much what I do, this simplifies the process I use by using the Base db (instead of reinit and stuffs) and stuff so that already helps a ton. Now it would be amazing if we could have a setTablePrefix("") or something so that we can set the table prefix, at the moment I use reflection to change the @ Table annotation and change the referenced table. So this ticket could be reopened for this exact case (a table prefix for a db)!

[ipolevoy]

@Articdive there is a way to fake it by using a sharding method, please see https://javalite.io/sharding.
I think between the example above and sharding, you can do what you need without any additional changes or reflection

[Articdive]

okay this seems to have worked thank you @ipolevoy!

[ipolevoy]

Awesome!