In src/groovy, create a groovy class named 'UserHolder' with following contents:
package a.b.c
/**
* Created by pritom on 14/08/2014.
*/
class UserHolder {
public static Integer DEFAULT = 1;
private static final ThreadLocal contextHolder = new ThreadLocal();
public static String DS_PREFIX = "dataSource_";
public static String DS_POSTFIX = "User";
static void setEnvironment(Map environment) {
contextHolder.set(environment);
}
static getEnvironment() {
return contextHolder.get();
}
static void clear() {
contextHolder.remove();
}
}
Also create a groovy class named 'SwitchableDataSource' in src/groovy with following contents:
package a.b.c
import grails.util.Holders
import org.springframework.context.ApplicationContext
import org.springframework.jdbc.datasource.DriverManagerDataSource
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource
import javax.sql.DataSource
/**
* Created by pritom on 14/08/2014.
*/
class SwitchableDataSource extends AbstractRoutingDataSource {
def applicationContext
public void setApplicationContext(ApplicationContext applicationContext) {
this.applicationContext = applicationContext
}
protected DataSource determineTargetDataSource() {
def user = UserHolder.getEnvironment();
try {
DriverManagerDataSource ds = super.determineTargetDataSource();
return ds;
}
catch (Exception ex) {
println "--->Error:: ${ex.getMessage()}";
try {
def ga = Holders.getGrailsApplication();
String beanFullName = UserHolder.DS_PREFIX + user.id + UserHolder.DS_POSTFIX;
if(user && user.id && ga.mainContext.containsBean( beanFullName ) ) {
println "Using data source: '${beanFullName}'";
return ga.mainContext.getBean(beanFullName);
}
}
catch (Exception ex2) {
println "--->Error:: ${ex2.getMessage()}";
}
}
}
@Override
protected Object determineCurrentLookupKey() {
def user = UserHolder.getEnvironment();
return user?.id ?: UserHolder.DEFAULT;
}
@Override
public void setTargetDataSources(Map<Object, Object> targetDataSources) {
super.setTargetDataSources(targetDataSources);
}
}
Edit resource.groovy file under grails-app/conf/spring folder:
import a.b.c.SwitchableDataSource
import a.b.c.UserHolder
import org.springframework.jdbc.datasource.DriverManagerDataSource
// Place your Spring DSL code here
beans = {
parentDataSource(DriverManagerDataSource) { bean ->
bean.'abstract' = true;
driverClassName = 'com.mysql.jdbc.Driver'
username = "root"
}
"rootDataSource"(DriverManagerDataSource) { bean ->
bean.parent = parentDataSource;
bean.scope = 'prototype';
url = "jdbc:mysql://localhost/user${UserHolder.DEFAULT}?useUnicode=yes&characterEncoding=UTF-8";
username = "root"
}
def dataSources = [:]
dataSources[UserHolder.DEFAULT] = ref("rootDataSource");
dataSource(SwitchableDataSource) {
targetDataSources = dataSources
}
}
Now create another groovy class named 'DataSourceService' to bind datasource to your project dynamically/runtime with following contents:
package a.b.c
import grails.spring.BeanBuilder
import org.codehaus.groovy.grails.commons.GrailsApplication
import org.springframework.beans.BeansException
import org.springframework.context.ApplicationContext
import org.springframework.context.ApplicationContextAware
import org.springframework.context.support.GenericApplicationContext
/**
* Created by pritom on 14/08/2014.
*/
class DataSourceService implements ApplicationContextAware {
ApplicationContext applicationContext;
public GrailsApplication grailsApplication;
@Override
void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
this.applicationContext = applicationContext;
}
/**
* Add new bean to system
* @param beanName
* @param dsurl
* @param uid
* @param pwd
* @return
*/
def registerBean( String beanName, String dsurl, String uid, String pwd ) {
String beanFullName = UserHolder.DS_PREFIX + beanName + UserHolder.DS_POSTFIX;
if( !applicationContext.containsBean( beanFullName ) ) {
def bb = new BeanBuilder()
bb.beans {
"$beanFullName" { bean ->
bean.parent = ref('parentDataSource');
bean.scope = 'prototype';
url = dsurl;
username = uid
password = pwd
}
}
bb.registerBeans( applicationContext );
println "Added $beanFullName"
}
else {
println "Already got a bean called $beanFullName"
}
}
/**
* Remove bean from system
* @param beanName
* @return
*/
def deRegisterBean( String beanName ) {
if( applicationContext.containsBean( beanName ) ) {
(applicationContext as GenericApplicationContext).removeBeanDefinition( beanName )
println "Removed $beanName"
}
else {
println "Trying to deRegister a bean $beanName that I don't know about"
}
}
}
Now create a filter in grails-app/filters named 'SecurityFilters' with following contents:
package filters
import a.b.c.UserHolder
class SecurityFilters {
def filters = {
all(controller: '*', action: '*') {
before = {
/* This line is for specify which user request to handle */
if (params.int('user')) {
UserHolder.setEnvironment([id: params.int('user')]);
}
}
after = { Map model ->
}
afterView = { Exception e ->
}
}
}
}
Example of adding a new datasource to system:
DataSourceService dataSourceService = new DataSourceService();
dataSourceService.setApplicationContext(grailsApplication.mainContext);
dataSourceService.grailsApplication = grailsApplication;
dataSourceService.registerBean(params.user, "jdbc:mysql://localhost/user${params.user}?useUnicode=yes&characterEncoding=UTF-8", "root", "");
Suppose params.user = 3 here.
That's it
