How to use datasource conditionally in applicationContext.xml - mysql

Question

I'm creating a GAE project with Spring which will also use cloud SQL. While testing this app in local I'm pointing to my local MySQL environment but when I'll deploy it to GAE, it will point to cloud SQL instance. So I want to configure my driverName in datasource bean depending on environment. To this we generally use following in our java code
if (SystemProperty.environment.value() == SystemProperty.Environment.Value.Production) {
// Load the class that provides the new "jdbc:google:mysql://" prefix.
Class.forName("com.mysql.jdbc.GoogleDriver");
url = "jdbc:google:mysql://<your-project-id>:<your-instance-name>/<your-database-name>?user=root";
} else {
// Local MySQL instance to use during development.
Class.forName("com.mysql.jdbc.Driver");
url = "jdbc:mysql://127.0.0.1:3306/<your-database-name>?user=root";
}
Now I want to achieve the same in applicationcontext.xml using Spring Expression language. I haven't done this before and not able to achieve it. Please guide me. This is what I tried
<bean id="isDev" class="java.lang.Boolean">
<constructor-arg value="#{ systemProperties[environment.value] == SystemProperty.Environment.Value.Development ? true : false }" />
</bean>
<bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="#{ isDev ? com.mysql.jdbc.Driver : com.mysql.jdbc.GoogleDriver }" />
.
.
.
But I'm getting exception, attaching a part of exception
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'feedbackFormController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.sandeepapplabs.custengage.services.FeedbackFormService com.sandeepapplabs.custengage.controllers.FeedbackFormController.feedbackFormService; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'feedbackFormService': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.sandeepapplabs.custengage.daos.FeedbackFormDAO com.sandeepapplabs.custengage.services.impl.FeedbackFormServiceImpl.feedbackFormDAO; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'feedbackFormDAO' defined in ServletContext resource [/WEB-INF/custengage-servlet.xml]: Cannot resolve reference to bean 'dataSource' while setting bean property 'dataSource'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in ServletContext resource [/WEB-INF/custengage-servlet.xml]: Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanExpressionException: Expression parsing failed; nested exception is org.springframework.beans.factory.BeanExpressionException: Expression parsing failed; nested exception is java.lang.NullPointerException

Answer 1

I believe you need to quote the class names to make them literals...
... 'com.mysql.jdbc.Driver' ...
However it is easier to use Spring Profiles](http://docs.spring.io/spring-framework/docs/current/spring-framework-reference/html/beans.html#beans-definition-profiles-xml) and enable the profile you want.

Answer 2

You can use Spring profiles to change concrete bean classes. Let's say you have 2 profiles: "prod" and "dev". Your bean methods should have #Profile annotation as below:
#Configuration
public class AppConfig {
...
#Bean
#Profile("prod")
public Object prodDataSource() {
return new ...
}
#Bean
#Profile("dev")
public Object getDataSource() throws Exception {
return new ...
}
}
If you are using Maven, you can select profile through pom.xml:
<profiles>
<profile>
<id>dev</id>
<activation>
<activeByDefault>true</activeByDefault>
</activation>
<properties>
<spring.profile>dev</spring.profile>
</properties>
</profile>
<profile>
<id>prod</id>
<activation>
<activeByDefault>false</activeByDefault>
<property>
<name>prod</name>
</property>
</activation>
<properties>
<spring.profile>prod</spring.profile>
</properties>
</profile>
</profiles>
You can pass profile selection argument by -D like: mvn -Dprod clean compile test install
EDIT:
In application.properties following property selects profile:
spring.profiles.active=${spring.profile}