Skip to main content

Part IV : A Simple and Smart Result Mapper

In my last post, I have shown how the dao support class changed to convert list of maps to list of domain objects. Now the DAO implementation class must also change to use these new methods. Here is the modified DAO class.
Listing – UserDaoImpl.java
package net.sf.dms.security.dao.impl;
import java.util.List;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import net.sf.dms.security.dao.api.UserDao;
import net.sf.dms.security.domain.User;
import net.sf.spring.dao.AbstractBaseDaoSupport;

/**
* @author dhrubo
* 
*/
public class UserDaoImpl extends AbstractBaseDaoSupport implements UserDao {

private Logger logger = LoggerFactory.getLogger(UserDaoImpl.class);
@Override
public List<User> listUsers() {
return (List<User>)this.queryForList("listUsers", User.class);
}

@Override
public void save(User user) {
this.insert("saveUser", user.getEmail(),
user.getPassword(), user.getFirstName(), user.getLastName());
}

@Override
public void update(User user) {

}
@Override
public User findUserByUserName(String username) {
logger.debug("Loading user details as part of authentication");
return (User)this.queryForObject("findUserByUserName", User.class, username);  
}

@Override
public List<User> findUsersStartingWith(String nameStartsWith) {
return (List<User>)this.queryForList("findUsersStartingWith", User.class, nameStartsWith + "%");  
}
}


Now you can see clearly that the list or finder queries have been reduced to just 1 line. I guess this code reduction is same as in any ORM or datamapper. Now let us see how the SQL has changed. I have tested this code on Postgresql 8.3 and should work with any sensible database available.
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">

<bean id="secSqlMap" class="org.springframework.beans.factory.config.MapFactoryBean">
<property name="sourceMap">
<map>
<entry key="listUsers">
<value>
<![CDATA[
SELECT first_name "firstName",last_name "lastName",email "userCode",user_id "userId" FROM t_user

]]>

</value>

</entry>

<entry key="saveUser">
<value>
<![CDATA[
INSERT INTO t_user(user_id, email, password, first_name,last_name) VALUES (nextval('t_user_seq'), ?, ?, ?, ?)

]]>

</value>

</entry>

<entry key="findUserByUserName">
<value>
<![CDATA[
SELECT first_name "firstName",last_name "latName",email "userCode",user_id "userId" FROM t_user WHERE email = ?

]]>

</value>

</entry>

<entry key="findUsersStartingWith">
<value>
<![CDATA[
SELECT first_name "firstName",last_name "latName",email "userCode",user_id "userId" FROM t_user 
WHERE first_name LIKE ?;

]]>

</value>

</entry>

</map>


</property>
</bean>

</beans>

Now you can see my source of meta data and how I use them to run this simple data mapper and move towards my goal of lightweight persistence and database independence.

Comments

Popular posts from this blog

Why do you need Spring Cloud Config server?

Last month I wrote a primer on concepts around 12 factor app. Before getting into the details of the Spring Cloud Config Server, I must refresh on the principle #3 from the list presented in that post.

3 – ConfigurationStore config in the environments
Configuration information must be separate from the source code. This may seem so obvious, but often we are guilty of leaving critical configuration parameters in the scattered in the code. Instead, applications should have environment specific configuration files. The sensitive information like database password or API key should be stored in these environment configuration files in encrypted format.
 The key takeaways from this postulate for a cloud-native microservices application are:
Do not store configuration as part of the deployable unit (in the case of lead microservice - inside the jar or war if you are still deploying war like the good old days). Instead, store it in an external location and make it easily accessible during run-…

Changing the root web application in Tomcat 6

These days I am very busy developing a large and complex web application, which is nearing its first release. This web based product runs on Tomcat 6 and will be deployed on http://www.mydomain.com
But if I deploy my web application on Tomcat 6, I need to specify the context root. Well this is no good, why will the users of this website be willing to remember the context root. What if the context root changes. In other words the users would not be interest in typing the following - http://www.mydomain.com/myappcontext to visit this site.
Hence it is necessary that I change the default / root web application of Tomcat and point it to my application. I wanted to try and test this on localhost first. As always I Googled and found a number of posts and none seem to work. I also read the documentation it was helpful in understanding the concepts but was not effective as I could not get it working. Finally after few hours of trial and error one of my colleague Joyeeta Majumdar found the so…

Part 3 - Integrating Tiles, Thymeleaf and Spring MVC 3

In this post I will demonstrate how to integrate Apache Tiles with Thymeleaf. This is very simple. The first step is to include the tiles and thymeleaf-tiles extension dependencies. I will include them in the pom.xml. Note we wil lbe using Tiles 2.2.2Listing 1 - parent/pom.xml --- thymeleaf-tiles and tiles dependencies <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<!-- Tiles -->
<!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->

<dependency>
<groupId>org.apache.tiles</groupId>
<artifactId>tiles-core</artifactId>
<version>${tiles.version}</version>
<scope>compile</scope>
</dependency>
<dependency>
<groupId>org.apache.tiles</groupId>
<artifactId>tiles-template</artifactId>
<version>${tiles.version}</version>
<scope>compile</scope>