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At line 2 changed 1 line.
This is a tutorial to show how to create and manage Hibernate relationships within [AppFuse]. This tutorial was written for AppFuse 1.8 and the AppGen pieces may not work with previous versions.
This is a tutorial to show how to create and manage Hibernate relationships within [AppFuse]. This tutorial was written using AppFuse 1.8.2. All of the code for this tutorial is downloadable at [http://static.appfuse.org/downloads/appfuse-hr.zip].
At line 6 added 2 lines.
%%note __NOTE:__ Copying the Java code in this tutorials [doesn't work in Firefox|http://raibledesigns.com/page/rd?anchor=java2html_plugin_for_jspwiki_causes]. A workaround is to CTRL+Click (Command+Click on OS X) the code block and then copy it.%%
At line 7 changed 2 lines.
* [1] Create Weblog.java, Entry.java and add XDoclet tags
* [2] [[Many-to-One] Create a new Category object and modify Entry.java to use it
* [1] Create Weblog.java, Entry.java and Category.java domain objects
* [2] [[Many-to-Many] A Weblogs can have many Users, a User can have many Weblogs
At line 10 changed 3 lines.
* [4] [[Many-to-Many] Shared Weblogs are possible for multiple Users
* [5] Lazy-Loading Issues
* [6] Managing relationships and indexed properties in the UI
* [4] [[Many-to-One] A Category object can be assigned to many entries
At line 16 changed 1 line.
In this example, the ''Weblog'' object is used to indentify a person's blog. This class has the following properties:
The ''Weblog'' object is used to indentify a person's blog. This class has the following properties:
At line 19 removed 1 line.
* username
At line 31 changed 1 line.
The first thing you need to do in this tutorial is these two object to persist. Create both a ''Weblog.java'' class and an ''Entry.java'' class (in the src/dao/**/model directory). The necessary XDoclet tags for these entities is included on the ''getter'' method's javadoc.
Below is a class diagram of these two objects, as well as the others you'll create in this tutorial.
At line 33 changed 2 lines.
* [View Weblog.java|Weblog.java]
* [View Entry.java|Entry.java]
[ER-Diagram.jpg]
At line 36 changed 1 line.
;:''Rather than fill up this tutorial with large blocks of Java code, the necessary files are attached and linked to. Small code snippets are used where appropriate.''
The first thing you need to do in this tutorial is these two object to persist. Create a __Weblog.java__ class and an __Entry.java__ class (in the src/dao/**/model directory). The necessary XDoclet tags for these entities is included on the ''getter'' method's javadoc. You can download these files using the links below. Note that javadocs have been eliminated for brevity.
At line 38 changed 1 line.
%%note __Tip:__ The equals(), hashCode() and toString() methods can be generated by your IDE. If you're using Eclipse, get the [Commonclipse|http://commonclipse.sourceforge.net/] plugin. For IDEA, the first two are built into the "Generate..." dialog, and toString() is a plugin you can download.%%
* [Download Weblog.java|Weblog.java]
* [Download Entry.java|Entry.java]
At line 40 changed 1 line.
!![[Many-to-One] Create a new Category object and modify Entry.java to use it [#2]
;:''Rather than fill up this tutorial with large blocks of Java code, the necessary files are attached and linked to. Small code snippets are used where appropriate. You should be able to easily download the files by right-clicking on them and selecting "Save Target As...".''
At line 42 changed 1 line.
A category object will act as an entity for persisting category information about weblog entries. A category object will consist of an id (primary key), category name, and a description. Each category can have many entries.
Create a __Category.java__ object to act as an entity for persisting category information about weblog entries. Each category can have many entries. This class contains the following properties:
At line 44 changed 1 line.
* [View Category.java|Category.java]
* categoryId
* name
* description
At line 46 changed 1 line.
The many-to-one relationship between entry and category can be established using XDoclet tags. Hibernate relationships can typically be established on either side of the relationship or as a bi-directional one as well. For our purposes,this relationship will be maintained by an extra property and collection held by Entry. The list of possible categories for a weblog entry will eventually be represented as a drop-down on the UI.
* [Download Category.java|Category.java]
At line 48 changed 1 line.
[{Java2HtmlPlugin
!Configure Spring
At line 50 changed 3 lines.
private Long categoryId;
private Category category;
Add the 3 new mapping files (that will be generated) to the "sessionFactory" bean's ''mappingResources'' property in __src/org/appfuse/dao/hibernate/applicationContext-hibernate.xml__.
At line 54 removed 29 lines.
/**
* @hibernate.many-to-one insert="false" update="false" cascade="none"
* column="category_id" outer-join="true"
*/
public Category getCategory() {
return category;
}
public void setCategory(Category category) {
this.category = category;
}
/**
* @hibernate.property column="category_id"
*/
public Long getCategoryId() {
return categoryId;
}
public void setCategoryId(Long categoryId) {
this.categoryId = categoryId;
}
}]
!![[One-to-Many] A Weblog object can have many Entries [#3]
Modify the Weblog object and Entry object to represent the multiplicity of a weblog that can have many entries. This relationship is set on the Weblog class using a list. XDoclet tags are used to establish this relationship using a __bag__ as the Hibernate collection type.
At line 85 changed 16 lines.
private List entries;
/**
* @return Returns the entries.
*
* @hibernate.bag name="entries" lazy="true" inverse="true" cascade="delete"
* @hibernate.collection-key column="weblog_id"
* @hibernate.collection-one-to-many class="org.appfuse.model.Entry"
*/
public List getEntries() {
return entries;
}
public void setEntries(List entries) {
this.entries = entries;
}
<property name="mappingResources">
<list>
<value>org/appfuse/model/Role.hbm.xml</value>
<value>org/appfuse/model/User.hbm.xml</value>
<value>org/appfuse/model/Weblog.hbm.xml</value>
<value>org/appfuse/model/Entry.hbm.xml</value>
<value>org/appfuse/model/Category.hbm.xml</value>
</list>
</property>
At line 103 changed 1 line.
The Entry class is modified slightly to provide a placeholder for the relationships between Weblog and Entry.
!![[Many-to-Many] A Weblogs can have many Users, a User can have many Weblogs [#2]
At line 105 changed 1 line.
[{Java2HtmlPlugin
A Weblog can have many Users. Basically the idea is of a shared weblog that is a place where many users can express themselves about a particular topic of interest. For this bit of functionality the User object will be modified to have a many-to-many relationship with Weblog.
At line 107 changed 1 line.
private Long weblogId;
Add the following ''users'' property and accessor methods to __Weblog.java__.
At line 109 removed 18 lines.
/**
* @hibernate.property column="weblog_id"
*/
public Long getWeblogId() {
return weblogId;
}
public void setWeblogId(Long weblogId) {
this.weblogId = weblogId;
}
}]
!![[Many-to-Many] [#4]
The Weblog system that we are developing allows one additional bit of functionality. A particular Weblog can have many Users. Basically the idea is of a shared weblog that is a place where many users can express themselves about a particular topic of interest. For this bit of functionality the User object will be modified to have a many-to-many relationship with Weblog.
Add the following ''users'' property and accessor methods to ''Weblog.java''.
At line 129 changed 1 line.
private Set users = new HashSet();
private List users = new ArrayList();
At line 132 changed 1 line.
* @hibernate.set table="weblog_user" cascade="none" lazy="false"
* @hibernate.bag table="weblog_user" cascade="save-update" lazy="true"
At line 136 changed 1 line.
public Set getUsers() {
public List getUsers() {
At line 144 changed 1 line.
public void setUsers(Set users) {
public void setUsers(List users) {
At line 94 added 2 lines.
%%note __NOTE:__ The reason a java.util.List is used instead of a java.util.Set is because this is because [Sets aren't supported for indexed properties in Struts|http://www.mail-archive.com/[email protected]/msg26289.html].%%
At line 151 changed 1 line.
In addition to allow navigation from a Weblog object to their list of users, you need to add a Set of Weblogs to the User object - allowing that path of navigation as well. Modify ''User.java'' to add a ''weblogs'' Set and accessor methods.
To allow navigation from a User objec to a list of Weblogs, you need to add a List of Weblogs to the User object. Modify ''User.java'' to add a ''weblogs'' List and accessor methods.
At line 155 changed 3 lines.
protected Set weblogs;
public Set getWeblogs() {
protected List weblogs;
/**
* @hibernate.bag table="weblog_user" cascade="save-update" lazy="true"
* @hibernate.collection-key column="username"
* @hibernate.collection-many-to-many class="org.appfuse.model.Weblog" column="weblog_id"
*/
public List getWeblogs() {
At line 161 changed 1 line.
public void setWeblogs(Set weblogs) {
public void setWeblogs(List weblogs) {
At line 166 changed 1 line.
!!DAO Stuff
!Test it!
At line 168 changed 1 line.
In order to test that all of this works, you need to create a ''WeblogDaoTest.java'' class. Create this class in ''test/dao/**/dao'' and fill it with the following code.
Create a unit test so you can verify that everything actually works. Create a __WeblogDaoTest__ class in your test/dao/**/dao directory. This file should extend GenericDaoTest. If you're using anything less than AppFuse 1.9, you may have to modify GenericDAOTest's "dao" variable so its __protected__ instead of private. Copy the code below into this test:
At line 170 removed 2 lines.
!WeblogDaoTest
At line 178 removed 3 lines.
import org.appfuse.Constants;
import org.appfuse.model.Address;
import org.appfuse.model.Weblog;
At line 182 changed 2 lines.
import org.springframework.dao.DataAccessException;
import org.springframework.dao.DataIntegrityViolationException;
import org.appfuse.model.Weblog;
At line 185 changed 1 line.
public class WeblogDaoTest extends BaseDaoTestCase {
public class WeblogDaoTest extends GenericDAOTest {
At line 187 changed 34 lines.
private WeblogDAO wldao = null;
private Weblog weblog = null;
private UserDAO udao = null;
private User user = null;
protected void setUp() throws Exception {
super.setUp();
wldao = (WeblogDAO) ctx.getBean("weblogDAO");
udao = (UserDAO) ctx.getBean("userDAO");
}
protected void tearDown() throws Exception {
super.tearDown();
wldao = null;
}
public void testGetWeblog() throws Exception {
weblog = wldao.getWeblog(new Long(1));
assertNotNull(weblog);
assertEquals(2, weblog.getUsers().size());
}
public void testUpdateWeblog() throws Exception {
weblog = wldao.getWeblog(new Long(2));
weblog.setBlogTitle("Testing Update Weblog");
wldao.saveWeblog(weblog);
assertEquals("Testing Update Weblog", weblog.getBlogTitle());
}
public void testAddWeblogUser() throws Exception {
weblog = wldao.getWeblog(new Long(2));
assertEquals(1, weblog.getUsers().size());
public void testWeblogAndUsers() throws Exception {
Weblog w = new Weblog();
w.setBlogTitle("My New Weblog");
w.setDateCreated(new Date());
At line 222 changed 3 lines.
user = udao.getUser("tomcat");
weblog.addUser(user);
wldao.saveWeblog(weblog);
// add it to the database
dao.saveObject(w);
At line 226 changed 1 line.
assertEquals(2, weblog.getUsers().size());
w = (Weblog) dao.getObject(Weblog.class, w.getWeblogId());
At line 228 changed 5 lines.
// add the same user twice - should result in no additional user
weblog.addUser(user);
wldao.saveWeblog(weblog);
assertEquals("more than 2 of the same users", 2, weblog.getUsers().size());
assertTrue(w.getUsers().isEmpty());
At line 234 changed 11 lines.
weblog.getUsers().remove(user);
wldao.saveWeblog(weblog);
assertEquals(1, weblog.getUsers().size());
}
public void testAddAndRemoveWeblog() throws Exception {
weblog = new Weblog();
weblog.setBlogTitle("A new test for adding and then deleting a weblog");
weblog.setDateCreated(new Date(2005-04-17));
weblog.setUsername("Cartman");
// add a user
User u = (User) dao.getObject(User.class, "mraible");
w.addUser(u);
At line 246 changed 1 line.
wldao.saveWeblog(weblog);
dao.saveObject(w);
At line 248 changed 2 lines.
assertNotNull(weblog.getBlogTitle());
assertEquals("Cartman", weblog.getUsername());
w = (Weblog) dao.getObject(Weblog.class, w.getWeblogId());
At line 251 changed 1 line.
wldao.removeWeblog(weblog.getWeblogId());
assertTrue(w.getUsers().size() == 1);
At line 253 changed 6 lines.
try {
weblog = wldao.getWeblog(weblog.getWeblogId());
fail("saveWeblog didn't throw DataAccessException");
} catch (DataAccessException d) {
assertNotNull(d);
}
// remove the user
w.setUsers(null);
dao.saveObject(w);
w = (Weblog) dao.getObject(Weblog.class, w.getWeblogId());
assertNull(w.getUsers());
At line 263 changed 1 line.
This test relies on some sample data, so add the following XML to __metadata/sql/sample-data.xml__.
Make sure you run __ant setup-db__ before running __ant test-dao -Dtestcase=UserDAO__. When running the test, you'll probably get a ''LazyInitializationException''. To solve this, change BaseDaoTestCase to extend Spring's [AbstractTransactionalDataSourceSpringContextTests|http://www.springframework.org/docs/api/org/springframework/test/AbstractTransactionalDataSourceSpringContextTests.html] if it doesn't already. In additional, you'll need to make a few changes to the existing tests so all the tests pass. [Here is a patch|LazyDaoTests.diff]. At a minimum, you'll need to fix BaseDAOTestCase and GenericDAOTest (onSetUp() -> onSetupBeforeTransaction()).
At line 265 changed 38 lines.
<div style="color: blue !important; margin-left: 50px">
{{{
<table name='weblog'>
<column>weblog_id</column>
<column>blog_title</column>
<column>date_created</column>
<column>username</column>
<row>
<value>1</value>
<value><![CDATA[Sponge Bob is Cool]]></value>
<value>2004-03-31</value>
<value>tomcat</value>
</row>
<row>
<value>2</value>
<value><![CDATA[Java Development = Fun]]></value>
<value>2005-01-05</value>
<value>mraible</value>
</row>
</table>
<table name='weblog_user'>
<column>weblog_id</column>
<column>username</column>
<row>
<value>1</value>
<value>tomcat</value>
</row>
<row>
<value>1</value>
<value>mraible</value>
</row>
<row>
<value>2</value>
<value>mraible</value>
</row>
</table>
}}}
</div>
Because the WeblogDaoTest is now extending AbstractTransactionalDataSourceSpringContextTests (ATDSSCT), there is a "jdbcTemplate" variable you can use to do additional querying. For instance, you could add the following at the end of your ''testWeblogAndUsers()'' method:
At line 304 removed 2 lines.
Before this test will compile, you need to create the WeblogDAO interface and implementation. Create a ''WeblogDAO.java'' interface in src/dao/**/dao:
At line 308 changed 11 lines.
package org.appfuse.dao;
import java.util.List;
import org.appfuse.model.Weblog;
public interface WeblogDAO extends Dao{
public Weblog getWeblog(Long weblogId);
public List getWeblogs(Weblog weblog);
public void saveWeblog(Weblog weblog);
public void removeWeblog(Long weblogId);
}
String qry = "select count(*) from weblog_user where username = 'mraible' " +
" and weblog_id = " + w.getWeblogId();
assertEquals(0, jdbcTemplate.queryForInt(qry));
At line 177 added 1 line.
!![[One-to-Many] A Weblog object can have many Entries [#3]
At line 322 changed 1 line.
Then create the Hibernate implementation of this interface in the src/dao/**/dao/hibernate directory.
Now you'll modify the __Weblog__ object and __Entry__ object to represent the multiplicity of a weblog that can have many entries. This relationship is set on the Weblog class using a java.util.List. XDoclet tags are used to establish this relationship using a __bag__ as the Hibernate collection type. Add the following code to your __Weblog.java__ class.
At line 326 changed 1 line.
package org.appfuse.dao.hibernate;
private List entries;
At line 328 changed 1 line.
import java.util.List;
/**
* @return Returns the entries.
*
* @hibernate.bag name="entries" lazy="false" cascade="all"
* @hibernate.collection-key column="weblog_id"
* @hibernate.collection-one-to-many class="org.appfuse.model.Entry"
*/
public List getEntries() {
return entries;
}
At line 330 changed 3 lines.
import org.appfuse.dao.WeblogDAO;
import org.appfuse.model.Weblog;
import org.springframework.orm.ObjectRetrievalFailureException;
public void setEntries(List entries) {
this.entries = entries;
}
}]
At line 334 changed 4 lines.
public class WeblogDAOHibernate extends BaseDaoHibernate implements WeblogDAO {
public Weblog getWeblog(Long weblogId) {
Weblog weblog = (Weblog) getHibernateTemplate().get(Weblog.class, weblogId);
Modify the __Entry__ class is so it contains a foreign key to its parent __Weblog__ class.
At line 339 changed 4 lines.
if (weblog == null) {
log.warn("uh oh, weblog '" + weblogId + "' not found...");
throw new ObjectRetrievalFailureException(Weblog.class, weblogId);
}
[{Java2HtmlPlugin
At line 344 changed 2 lines.
return weblog;
}
private Long weblogId;
At line 347 changed 2 lines.
public List getWeblogs(Weblog weblog) {
return getHibernateTemplate().find("from Weblog wl order by upper(wl.blogTitle)");
/**
* @hibernate.property column="weblog_id"
*/
public Long getWeblogId() {
return weblogId;
At line 351 changed 2 lines.
public void saveWeblog(final Weblog weblog) {
getHibernateTemplate().saveOrUpdate(weblog);
public void setWeblogId(Long weblogId) {
this.weblogId = weblogId;
At line 354 removed 5 lines.
public void removeWeblog(Long weblogId) {
getHibernateTemplate().delete(getWeblog(weblogId));
}
}
At line 361 changed 1 line.
!Configure Spring for WeblogDAO
At this point, you could add an additional test method to WeblogDaoTest to test that this relationship works. Of course, you'll need to run __ant setup-db__ to make sure your database knows about the relationship.
At line 363 changed 1 line.
Modifications need to be made in applicationContext-hibernate.xml for the 3 new entities you created in this tutorial.
!![[Many-to-One] A Category object can be assigned to many entries [#4]
At line 223 added 2 lines.
The ''many-to-one'' relationship between __Category__ and __Entry__ can be established using XDoclet tags. Hibernate relationships can be established on either side of the relationship or bi-directionally. For this tutorial, this relationship is maintained by a __categoryId__ property and a __Category__ object in __Entry__. The list of possible categories for a weblog entry will eventually be represented as a drop-down on the UI. Add the following code to your __Entry.java__ class. Notice that the relationship to __Category__ has ''insert="false" update="false"''. This is because the object is read-only. This can be useful for displaying a category's name on the UI when you're viewing an Entry.
At line 367 changed 11 lines.
<property name="mappingResources">
<list>
<value>org/appfuse/model/Role.hbm.xml</value>
<value>org/appfuse/model/User.hbm.xml</value>
<value>org/appfuse/model/UserCookie.hbm.xml</value>
<value>org/appfuse/model/Weblog.hbm.xml</value>
<value>org/appfuse/model/Entry.hbm.xml</value>
<value>org/appfuse/model/Category.hbm.xml</value>
</list>
</property>
}]
private Long categoryId;
private Category category;
At line 230 added 7 lines.
/**
* @hibernate.many-to-one insert="false" update="false" cascade="none"
* column="category_id" outer-join="true"
*/
public Category getCategory() {
return category;
}
At line 380 changed 1 line.
Also, you need to add the "weblogDAO" bean definition.
public void setCategory(Category category) {
this.category = category;
}
At line 382 changed 1 line.
[{Java2HtmlPlugin
/**
* @hibernate.property column="category_id"
*/
public Long getCategoryId() {
return categoryId;
}
At line 384 changed 4 lines.
<!-- WeblogDAO: Hibernate implementation -->
<bean id="weblogDAO" class="org.appfuse.dao.hibernate.WeblogDAOHibernate">
<property name="sessionFactory"><ref local="sessionFactory"/></property>
</bean>
public void setCategoryId(Long categoryId) {
this.categoryId = categoryId;
}
At line 254 added 1 line.
After making these changes, your __WeblogDaoTest__ should still pass. Verify it does by running __ant setup-db test-dao -Dtestcase=Weblog__.
At line 391 changed 1 line.
After making these changes, you should be able to run __ant test-dao -Dtestcase=WeblogDAO__. All of the tests should pass successfully.
''__Yeah baby, Yeah!__''
%%(color: green)
BUILD SUCCESSFUL\\
Total time: 24 seconds
%%
At line 393 changed 1 line.
!!Lazy-Loading Issues [#5]
Before working on the UI, it's helpful to have some sample data so you don't have to do manual data entry. Add the following XML to the bottom of __metadata/sql/sample-data.xml__.
At line 395 changed 1 line.
!!Managing relationships and indexed properties in the UI [#6]
<div style="color: blue !important; margin-left: 50px">
{{{
<table name='weblog'>
<column>weblog_id</column>
<column>blog_title</column>
<column>date_created</column>
<row>
<value>1</value>
<value><![CDATA[Sponge Bob is Cool]]></value>
<value>2004-03-31</value>
</row>
<row>
<value>2</value>
<value><![CDATA[Java Development = Fun]]></value>
<value>2005-01-05</value>
</row>
</table>
<table name='weblog_user'>
<column>weblog_id</column>
<column>username</column>
<row>
<value>1</value>
<value>tomcat</value>
</row>
<row>
<value>1</value>
<value>mraible</value>
</row>
<row>
<value>2</value>
<value>mraible</value>
</row>
</table>
<table name='category'>
<column>category_id</column>
<column>name</column>
<column>description</column>
<row>
<value>1</value>
<value><![CDATA[Struts vs. Spring MVC]]></value>
<value><![CDATA[Comparing implementations of the MVC Design Pattern]]></value>
</row>
<row>
<value>2</value>
<value><![CDATA[Cycling Notes]]></value>
<value><![CDATA[All about cycling in the US.]]></value>
</row>
<row>
<value>3</value>
<value><![CDATA[Cyclocross]]></value>
<value><![CDATA[Bog Trotters Unite!]]></value>
</row>
</table>
<table name='entry'>
<column>entry_id</column>
<column>entry_text</column>
<column>time_created</column>
<column>weblog_id</column>
<column>category_id</column>
<row>
<value>1</value>
<value><![CDATA[Testing]]></value>
<value>2005-04-11 01:02:03.4</value>
<value>1</value>
<value>1</value>
</row>
<row>
<value>2</value>
<value><![CDATA[Test Value]]></value>
<value>2005-04-12 01:02:03.4</value>
<value>1</value>
<value>1</value>
</row>
<row>
<value>3</value>
<value><![CDATA[Test Value 3]]></value>
<value>2005-04-12 01:02:03.4</value>
<value>2</value>
<value>3</value>
</row>
</table>
}}}
</div>
----
''Next Up:'' __Part II:__ [Create Weblog UI|HibernateRelationshipsUI] - Creating a UI to manage the relationships created in this tutorial.

Back to HibernateRelationships, or to the Page History.