It s unclear to me how the default connection works The docs

Question

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 · Answer

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 · Answer

Sure did It s the same problem that you can t control the connection order of beans

hichem fazai · Answer

Are you calling `Database connect` in your code

Joel · Answer

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 · Answer

which is stored in a `ThreadLocal` unsure how that works with coroutines

tapac · Answer

< Joel> why do you need to call `Database connect` Do you work with different databases

Joel · Answer

< tapac> yes indeed

Joel · Answer

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

Joel · Answer

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 · Answer

I would advice either use primary db instance as an argument too or make function like ```fun lt T gt primaryTransaction body Transaction gt T = transaction primaryDbInstance body ```

Joel · Answer

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 · Answer

< 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 · Answer

< hichem fazai> that is what I am attempting to create

Joel · Answer

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 · Answer

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