Posts Tagged ‘database’

The @Bean annotation is a great way to declare Spring beans when writing code.  This allows the programmer to control which beans get instantiated and with what arguments.   Some situations call for deciding if beans should be instantiated at runtime based on configuration this is often done with the @Conditional annotation on @Configuration classes.   The @Conditional annotation works well if you are enabling or disabling a particular bean through configuration but sometimes the number of beans needs to be completely dynamic.

This often comes up if your application needs to connect to a bunch of external services such as a database.  You want the number of  services or databases that the application connects to be configurable.


I was recently working on a project where we had about half a dozen developers working on an established code base. All of the developers were new to the code base and I knew that we were going to be making a fair number of database schema and data-seeding changes in a short period of time. Each developer had their own development environment with a dedicated database (PostgreSQL). The developers on the project had their hands full learning about the code base and I didn’t want to distract them by having to take a lot of their time managing their development database instances.

I decided to try using Alembic to manage the database schema migrations.