Grails: Create dynamic SQL-Connection

Question

For my application I need dynamic database connections at runtime. I know, there are ways to create multiple datasources but they are not that dynamically I think. Scenari

Answer 1

You can do this sort of thing to register DataSource beans at runtime:

Given a Grails Service:

package whatever

import groovy.sql.Sql
import org.springframework.context.*
import org.apache.tomcat.jdbc.pool.DataSource
import org.springframework.context.support.GenericApplicationContext

class DataSourceService implements ApplicationContextAware {

    ApplicationContext  applicationContext

    def registerBean( String beanName, String dsurl, String uid, String pwd ) {
        if( !applicationContext.containsBean( beanName ) ) {
            def bb = new grails.spring.BeanBuilder()
            bb.beans {
                "$beanName"( DataSource ) {
                    driverClassName = "com.mysql.jdbc.Driver"
                    url             = dsurl
                    username        = uid
                    password        = pwd
                    validationQuery = "SELECT 1"
                    testOnBorrow    = true
                    maxActive       = 1
                    maxIdle         = 1
                    minIdle         = 1
                    initialSize     = 1
                }
            }
            bb.registerBeans( applicationContext )
            log.info "Added $beanName"
        }
        else {
            log.error "Already got a bean called $beanName"
        }
    }

    def deRegisterBean( String beanName ) {
        if( applicationContext.containsBean( beanName ) ) {
            (applicationContext as GenericApplicationContext).removeBeanDefinition( beanName )
            log.info "Removed $beanName"
        }
        else {
            log.error "Trying to deRegister a bean $beanName that I don't know about"
        }
    }

    def getSql( String beanName ) {
        Sql.newInstance( applicationContext.getBean( beanName ) )
    }
}

Then, you should be able to call the service to register a new datasource:

dataSourceService.registerBean( 'myDS', 'jdbc:mysql://localhost:3306/mysql', 'test', 'test' )

Get a Groovy Sql object for it:

dataSourceService.getSql( 'myDS' ).rows( 'SELECT * FROM whatever' )

And remove the bean when done

dataSourceService.deRegisterBean( 'myDS' )

Fingers crossed... I've yanked that code from a project of mine and changed/not-tested it ;-)

Update

The runtime-datasources plugin has been created which uses the approach outlined in this post to allow datasources to be added/removed at runtime.