It's unclear to me how the default connection work...

# exposed

[Joel]

It's unclear to me how the default connection works. The docs say the latest connection is the default. Does this truly mean that the latest call of Database.connect is the default db? This is inconvenient when working with Spring Boot because bean creation order is undefined.

[hichem fazai]

Did you make a try with exposed-spring-boot-starter (https://github.com/JetBrains/Exposed/tree/master/exposed-spring-boot-starter) ?
You just need to put you connection parameters in application.properties

[Joel]

Sure did. It’s the same problem that you can’t control the connection order of beans.

[hichem fazai]

Are you calling Database.connect in your code?

[Joel]

Yes. The spring starter calls it as well when it wires up the transaction manager. The problem is that the final call to Database.connect is considered the default connection if you call transaction without a db argument.

[Joel]

(which is stored in a ThreadLocal? unsure how that works with coroutines)

[tapac]

@Joel, why do you need to call Database.connect? Do you work with different databases?

[Joel]

@tapac yes indeed

[Joel]

We have a primary and a legacy that is being wired up for future migrations

[Joel]

All of the legacy queries specify the legacy database as a transaction argument, but we need to ensure that the default no-arg db is the primary

[tapac]

I would advice either use primary db instance as an argument too or make function like

fun <T> primaryTransaction(body : Transaction.()->T) = transaction(primaryDbInstance) { body() }

[Joel]

I have a number of methods that rely on the no-arg transaction. I'd prefer to not have to refactor all of them.

[hichem fazai]

@Joel If I understood correctly, you see that correct behaviour is that transaction(leagacy-db-con) uses leagacy db connection and transaction without arguments uses connection defined in application.properties ?

[Joel]

@hichem fazai that is what I am attempting to create

[Joel]

I've introduced the spring transaction manager which does a nice job at creating a context such that you don't need to specify transaction within models. However the spring transaction manager opens its own db connection, which also provides a bit of headache when trying to get these all in the correct order.

[Joel]

A solid improvement would be to create a spring transaction manager with a db argument so that I can control ordering myself.