How do I access the database from within a jakarta servlet Filter?

Question

I'm working on a Spring Boot web application and I'm implementing a filter (jakarta.servlet.Filter) for authentication. The filter needs some information from the database before it can authenticate the provided credentials, but I can't figure out how to get at the data because it's outside of the context of the Spring framework.

If I define a reference to a repository (org.springframework.stereotype.Repository) it doesn't get populated, it remains null. eg:

@Component
public class AuthFilter implements Filter {
    private SystemPropertyReposity spr;   // <-- null

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        SystemProperty sp = spr.findByPropertyKey(CLIENT_ID_KEY); // <-- NullPointerException because spr is null.
    }
}

@Repository
public interface SystemPropertyRepository extends JpaRepository<SystemProperty, Integer>{
    SystemProperty findByPropertyKey(String propertyKey);
}

I have the following set in my application.properties:

spring.datasource.url=jdbc:postgresql://localhost:5432/mypostgresdb
spring.datasource.username=####
spring.datasource.password=####
spring.jpa.properties.hibernate.jdbc.lob.non_contextual_creation= true
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.PostgreSQLDialect

Elsewhere in my application, wherever it's within a Spring framework context, I'm able to access the database without problem. It's probably something simple I've overlooked, but how am I supposed to get at my database from within my filter?

Answer 1

You are missing an @Autowired on the SystemPropertyReposity spr field or, even better a constructor