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HibernateRelationshi...




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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 using AppFuse 1.8. All of the code for this tutorial is downloadable. To begin, I created a new application with an app/db name of blog/blog.
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 4 lines.
* [4] [[Many-to-Many] Shared Weblogs are possible for multiple Users
* [5] [[DAO Stuff] Setting up Unit Tests and DAO classes for basic CRUD
* [6] Lazy-Loading Issues
* [7] Managing relationships and indexed properties in the UI
* [4] [[Many-to-One] A Category object can be assigned to many entries
At line 17 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 20 removed 1 line.
* username
At line 32 changed 1 line.
<div style="color: green; margin-left: 20px; background: #ffd">TODO: Create diagram of the tables and their relationships.</div>
Below is a class diagram of these two objects, as well as the others you'll create in this tutorial.
At line 34 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. You can download these files using the links below. Note that javadocs have been eliminated for brevity.
[ER-Diagram.jpg]
At line 34 added 2 lines.
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 39 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.''
;:''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 41 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.%%
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 43 changed 1 line.
!![[Many-to-One] Create a new Category object and modify Entry.java to use it [#2]
* categoryId
* name
* description
At line 45 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.
* [Download Category.java|Category.java]
At line 47 changed 1 line.
* [View Category.java|Category.java]
!Configure Spring
At line 49 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.
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 53 changed 27 lines.
private Long categoryId;
private Category category;
/**
* @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;
}
<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 82 changed 1 line.
!![[One-to-Many] A Weblog object can have many Entries [#3]
!![[Many-to-Many] A Weblogs can have many Users, a User can have many Weblogs [#2]
At line 84 changed 1 line.
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.
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 86 changed 1 line.
[{Java2HtmlPlugin
Add the following ''users'' property and accessor methods to __Weblog.java__.
At line 88 removed 20 lines.
private List entries;
/**
* @return Returns the entries.
*
* @hibernate.bag name="entries" lazy="false" 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;
}
}]
The Entry class is modified slightly to provide a placeholder for the relationships between Weblog and Entry.
At line 110 changed 23 lines.
private Long weblogId;
/**
* @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''.
[{Java2HtmlPlugin
private Set users = new HashSet();
private List users = new ArrayList();
At line 135 changed 1 line.
* @hibernate.set table="weblog_user" cascade="none" lazy="false"
* @hibernate.bag table="weblog_user" cascade="save-update" lazy="true"
At line 139 changed 1 line.
public Set getUsers() {
public List getUsers() {
At line 147 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 154 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 158 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 164 changed 1 line.
public void setWeblogs(Set weblogs) {
public void setWeblogs(List weblogs) {
At line 169 changed 1 line.
!![[DAO Stuff] [#5]
!Test it!
At line 171 changed 1 line.
In order to test that all of this works, you need to create some test classes, add some sample data, develop some DAO interfaces, and create hibernate DAO classes.
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 173 removed 6 lines.
!!Test Classes
!WeblogDaoTest
Let's start with ''WeblogDaoTest.java'' class. Create this class in ''test/dao/**/dao'' and fill it with the following code.
At line 184 removed 1 line.
import java.util.List;
At line 186 removed 1 line.
import org.appfuse.model.Weblog;
At line 188 changed 1 line.
import org.springframework.dao.DataAccessException;
import org.appfuse.model.Weblog;
At line 190 changed 6 lines.
public class WeblogDaoTest extends BaseDaoTestCase {
private WeblogDAO wldao = null;
private Weblog weblog = null;
private UserDAO udao = null;
private User user = null;
public class WeblogDaoTest extends GenericDAOTest {
At line 197 changed 30 lines.
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 228 changed 3 lines.
user = udao.getUser("tomcat");
weblog.addUser(user);
wldao.saveWeblog(weblog);
// add it to the database
dao.saveObject(w);
At line 232 changed 1 line.
assertEquals(2, weblog.getUsers().size());
w = (Weblog) dao.getObject(Weblog.class, w.getWeblogId());
At line 234 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 240 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 252 changed 1 line.
wldao.saveWeblog(weblog);
dao.saveObject(w);
At line 254 changed 2 lines.
assertNotNull(weblog.getBlogTitle());
assertEquals("Cartman", weblog.getUsername());
w = (Weblog) dao.getObject(Weblog.class, w.getWeblogId());
At line 257 changed 1 line.
wldao.removeWeblog(weblog.getWeblogId());
assertTrue(w.getUsers().size() == 1);
At line 259 changed 11 lines.
try {
weblog = wldao.getWeblog(weblog.getWeblogId());
fail("saveWeblog didn't throw DataAccessException");
} catch (DataAccessException d) {
assertNotNull(d);
}
}
public void testGetEntries() throws Exception {
List list = wldao.getEntries(new Long(1));
assertTrue(list.size() > 0);
// remove the user
w.setUsers(null);
dao.saveObject(w);
At line 159 added 3 lines.
w = (Weblog) dao.getObject(Weblog.class, w.getWeblogId());
assertNull(w.getUsers());
At line 272 removed 6 lines.
At line 281 changed 1 line.
!EntryDaoTest
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 283 changed 1 line.
Now, create an ''EntryDaoTest.java'' class. Again, create this class in ''test/dao/**/dao'' and fill it with the following code.
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 287 changed 64 lines.
package org.appfuse.dao;
import java.sql.Timestamp;
import org.appfuse.model.Entry;
import org.springframework.dao.DataAccessException;
public class EntryDaoTest extends BaseDaoTestCase {
private EntryDAO edao = null;
private Entry entry = null;
protected void setUp() throws Exception {
super.setUp();
edao = (EntryDAO) ctx.getBean("entryDAO");
}
protected void tearDown() throws Exception {
super.tearDown();
edao = null;
}
public void testGetEntry() throws Exception {
entry = edao.getEntry(new Long(1));
assertNotNull(entry);
assertEquals("Testing", entry.getText());
}
public void testUpdateEntry() throws Exception {
entry = edao.getEntry(new Long(2));
entry.setText("Testing update entry");
entry.setCategoryId(new Long(2));
edao.saveEntry(entry);
assertEquals("Testing update entry", entry.getText());
}
public void testAddAndRemoveEntry() throws Exception {
entry = new Entry();
entry.setText("Testing add a new entry");
entry.setTimeCreated(new Timestamp(2004-04-02));
entry.setCategoryId(new Long(3));
entry.setWeblogId(new Long(1));
edao.saveEntry(entry);
assertNotNull(entry.getText());
assertEquals("Testing add a new entry", entry.getText());
edao.removeEntry(entry.getEntryId());
try {
entry = edao.getEntry(entry.getEntryId());
fail("saveEntry didn't throw DataAccessException");
} catch (DataAccessException d) {
assertNotNull(d);
}
}
}
String qry = "select count(*) from weblog_user where username = 'mraible' " +
" and weblog_id = " + w.getWeblogId();
assertEquals(0, jdbcTemplate.queryForInt(qry));
At line 353 changed 1 line.
!CategoryDaoTest
!![[One-to-Many] A Weblog object can have many Entries [#3]
At line 355 changed 1 line.
Next, create an ''CategoryDaoTest.java'' class in ''test/dao/**/dao''.
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 359 changed 1 line.
package org.appfuse.dao;
private List entries;
At line 361 changed 11 lines.
import org.appfuse.model.Category;
import org.springframework.dao.DataAccessException;
public class CategoryDaoTest extends BaseDaoTestCase {
private CategoryDAO catdao = null;
private Category category = null;
protected void setUp() throws Exception {
super.setUp();
catdao = (CategoryDAO) ctx.getBean("categoryDAO");
/**
* @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 373 removed 8 lines.
protected void tearDown() throws Exception {
super.tearDown();
catdao = null;
}
public void testGetCategory() throws Exception {
category = catdao.getCategory(new Long(1));
At line 382 changed 2 lines.
assertNotNull(category);
assertEquals("Struts v. Spring MVC", category.getCategoryName());
public void setEntries(List entries) {
this.entries = entries;
At line 385 removed 33 lines.
public void testUpdateCategory() throws Exception {
category = catdao.getCategory(new Long(2));
category.setCategoryName("Testing update category");
catdao.saveCategory(category);
assertEquals("Testing update category", category.getCategoryName());
}
public void testAddAndRemoveCategory() throws Exception {
category = new Category();
category.setCategoryName("Spaceman Biff");
category.setCategoryDescription("Paying homage to Calvin's alter ego!");
catdao.saveCategory(category);
assertNotNull(category.getCategoryDescription());
assertEquals("Spaceman Biff", category.getCategoryName());
catdao.removeCategory(category.getCategoryId());
try {
category = catdao.getCategory(category.getCategoryId());
fail("saveCategory didn't throw DataAccessException");
} catch (DataAccessException d) {
assertNotNull(d);
}
}
}
At line 420 changed 1 line.
All of these tests rely on some sample data, so add the following XML to __metadata/sql/sample-data.xml__.
Modify the __Entry__ class is so it contains a foreign key to its parent __Weblog__ class.
At line 422 removed 94 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>
<table name='category'>
<column>category_id</column>
<column>category_name</column>
<column>category_description</column>
<row>
<value>1</value>
<value><![CDATA[Struts v. 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</value>
<value>1</value>
<value>1</value>
</row>
<row>
<value>2</value>
<value><![CDATA[Test Value]]></value>
<value>2005-04-12</value>
<value>1</value>
<value>1</value>
</row>
<row>
<value>3</value>
<value><![CDATA[Test Value 3]]></value>
<value>2005-04-12</value>
<value>2</value>
<value>3</value>
</row>
</table>
}}}
</div>
!!DAO Interfaces
Before any of these tests will compile, you need to create the DAO interfaces and then implementations.
!WeblogDAO Interface
Create a ''WeblogDAO.java'' interface in src/dao/**/dao:
At line 518 changed 1 line.
package org.appfuse.dao;
private Long weblogId;
At line 520 changed 131 lines.
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);
public List getEntries(Long weblogId);
}
}]
!EntryDAO Interface
[{Java2HtmlPlugin
package org.appfuse.dao;
import java.util.List;
import org.appfuse.model.Entry;
public interface EntryDAO {
public Entry getEntry(Long entryId);
public List getEntries(Entry entry);
public void saveEntry(Entry entry);
public void removeEntry(Long entryId);
}
}]
!CategoryDAO Interface
[{Java2HtmlPlugin
package org.appfuse.dao;
import java.util.List;
import org.appfuse.model.Category;
public interface CategoryDAO {
public Category getCategory(Long categoryId);
public List getCategories(Category category);
public void saveCategory(Category category);
public void removeCategory(Long categoryId);
}
}]
!!DAO Implementation
Then create the Hibernate implementations of the interfaces in the src/dao/**/dao/hibernate directory.
!WeblogDAOHibernate
[{Java2HtmlPlugin
package org.appfuse.dao.hibernate;
import java.util.List;
import org.appfuse.dao.WeblogDAO;
import org.appfuse.model.Weblog;
import org.springframework.orm.ObjectRetrievalFailureException;
public class WeblogDAOHibernate extends BaseDaoHibernate implements WeblogDAO {
public Weblog getWeblog(Long weblogId) {
Weblog weblog = (Weblog) getHibernateTemplate().get(Weblog.class,
weblogId);
if (weblog == null) {
log.warn("uh oh, weblog '" + weblogId + "' not found...");
throw new ObjectRetrievalFailureException(Weblog.class, weblogId);
}
return weblog;
}
public List getWeblogs(Weblog weblog) {
return getHibernateTemplate().find(
"from Weblog wl order by upper(wl.blogTitle)");
}
public void saveWeblog(final Weblog weblog) {
getHibernateTemplate().saveOrUpdate(weblog);
}
public void removeWeblog(Long weblogId) {
getHibernateTemplate().delete(getWeblog(weblogId));
}
public List getEntries(Long weblogId) {
return getHibernateTemplate().find("from Entry e where e.weblogId=?",
weblogId);
}
}
}]
!EntryDAOHibernate
[{Java2HtmlPlugin
package org.appfuse.dao.hibernate;
import java.util.List;
import org.appfuse.dao.EntryDAO;
import org.appfuse.model.Entry;
import org.springframework.orm.ObjectRetrievalFailureException;
public class EntryDAOHibernate extends BaseDaoHibernate implements EntryDAO {
public Entry getEntry(Long entryId) {
Entry entry = (Entry) getHibernateTemplate().get(Entry.class, entryId);
if (entry == null) {
log.warn("uh oh, weblog '" + entryId + "' not found...");
throw new ObjectRetrievalFailureException(Entry.class, entryId);
}
return entry;
/**
* @hibernate.property column="weblog_id"
*/
public Long getWeblogId() {
return weblogId;
At line 653 changed 2 lines.
public List getEntries(Entry entry) {
return getHibernateTemplate().find("from Entry e order by upper(e.timeCreated)");
public void setWeblogId(Long weblogId) {
this.weblogId = weblogId;
At line 217 added 1 line.
}]
At line 657 changed 3 lines.
public void saveEntry(final Entry entry) {
getHibernateTemplate().saveOrUpdate(entry);
}
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 661 changed 3 lines.
public void removeEntry(Long entryId) {
getHibernateTemplate().delete(getEntry(entryId));
}
!![[Many-to-One] A Category object can be assigned to many entries [#4]
At line 665 changed 1 line.
}
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 667 removed 4 lines.
}]
!CategoryDAOHibernate
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package org.appfuse.dao.hibernate;
private Long categoryId;
private Category category;
At line 675 changed 16 lines.
import java.util.List;
import org.appfuse.dao.CategoryDAO;
import org.appfuse.model.Category;
import org.springframework.orm.ObjectRetrievalFailureException;
public class CategoryDAOHibernate extends BaseDaoHibernate implements CategoryDAO {
public Category getCategory(Long categoryId) {
Category category = (Category) getHibernateTemplate().get(Category.class, categoryId);
if (category == null) {
log.warn("uh oh, weblog '" + categoryId + "' not found...");
throw new ObjectRetrievalFailureException(Category.class, categoryId);
}
/**
* @hibernate.many-to-one insert="false" update="false" cascade="none"
* column="category_id" outer-join="true"
*/
public Category getCategory() {
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public List getCategories(Category category) {
return getHibernateTemplate().find("from Category cat order by upper(cat.categoryName)");
public void setCategory(Category category) {
this.category = category;
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public void saveCategory(final Category category) {
getHibernateTemplate().saveOrUpdate(category);
/**
* @hibernate.property column="category_id"
*/
public Long getCategoryId() {
return categoryId;
At line 702 changed 2 lines.
public void removeCategory(Long categoryId) {
getHibernateTemplate().delete(getCategory(categoryId));
public void setCategoryId(Long categoryId) {
this.categoryId = categoryId;
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}
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!Configure Spring
After making these changes, your __WeblogDaoTest__ should still pass. Verify it does by running __ant setup-db test-dao -Dtestcase=Weblog__.
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Modifications need to be made in applicationContext-hibernate.xml for the 3 new entities you created in this tutorial.
''__Yeah baby, Yeah!__''
%%(color: green)
BUILD SUCCESSFUL\\
Total time: 24 seconds
%%
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[{Java2HtmlPlugin
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__.
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<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>
}]
<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>
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----
At line 729 changed 29 lines.
Also, you need to add the "weblogDAO", "entryDAO", and "categoryDAO" bean definitions.
[{Java2HtmlPlugin
<!-- WeblogDAO: Hibernate implementation -->
<bean id="weblogDAO" class="org.appfuse.dao.hibernate.WeblogDAOHibernate">
<property name="sessionFactory"><ref local="sessionFactory"/></property>
</bean>
<!-- EntryDAO: Hibernate implementation -->
<bean id="entryDAO" class="org.appfuse.dao.hibernate.EntryDAOHibernate">
<property name="sessionFactory"><ref local="sessionFactory"/></property>
</bean>
<!-- CategoryDAO: Hibernate implementation -->
<bean id="categoryDAO" class="org.appfuse.dao.hibernate.CategoryDAOHibernate">
<property name="sessionFactory"><ref local="sessionFactory"/></property>
</bean>
}]
After making these changes, you should be able to run __ant test-dao -Dtestcase=WeblogDAO__ for example. All of the tests should pass successfully.
!!Lazy-Loading Issues [#6]
Karl Baum has an [excellent article on lazy-loading|http://www.jroller.com/page/kbaum/20040708].
!!Managing relationships and indexed properties in the UI [#7]
''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.