Spring Boot JPA: How to avoid creating multiple repositories for identical databases? - database

Question

My spring boot mvc project interacts with a database via a repository interface, which works nicely using Spring boot default configurations:
spring:
datasource:
url: jdbc:mysql://localhost/some_schema
username:
...
#Configuration
#EnableJpaRepositories(basePackages = {"my.path.to.repository"})
public class Application extends WebMvcConfigurerAdapter {
....
Now depending on some runtime condition, I need to interact with an identical second database (same schema) in a separate location. The solutions I found all point to creating a separate repository package per datasource.
Since the databases are identical, however, is there an elegant way to avoid duplicating the repository package for each added datasource?

Answer 1

You can accomplish this with a Spring AbstractRoutingDataSource.
Roughly:
public class ChooseOneDataSource extends AbstractRoutingDataSource {
#Override
protected Object determineCurrentLookupKey() {
if (***some runtime condition***) {
return "dataSource1";
} else {
return "dataSource2";
}
}
}
And in your conguration:
#Bean
#ConfigurationProperties(prefix = "dataSource1")
DataSource dataSource1() {
return DataSourceBuilder.create().build();
}
#Bean
#ConfigurationProperties(prefix = "dataSource2")
DataSource dataSource2() {
return DataSourceBuilder.create().build();
}
#Bean
DataSource dataSource() {
AbstractRoutingDataSource dataSource = new ChooseOneDataSource();
Map<Object,Object> resolvedDataSources = new HashMap<>();
resolvedDataSource.put("dataSource1", dataSource1());
resolvedDataSource.put("dataSource2", dataSource2());
dataSource.setDefaultTargetDataSource(dataSource1()); // << default
dataSource.setTargetDataSources(resolvedDataSources);
return dataSource;
}
For more info/examples:
http://fizzylogic.nl/2016/01/24/Make-your-Spring-boot-application-multi-tenant-aware-in-2-steps/
https://spring.io/blog/2007/01/23/dynamic-datasource-routing/