Create a Blog with JBoss Seam, Hibernate JPA and JSF then Deploy it to Tomcat in the Cloud – Part IV

Seam Tomcat Deployment Tutorial Part 4
In this part of the tutorial we will correct the bugs inherent in version 2.2 of Seam-gen and we will add some code to spice up our blog CMS.

First of all, our PostEdit.seam page is not working at all as it is. We shall fix this:

Fixing the PostEdit.xhtml page

Figure 4.1 - Fixing the PostEdit.xhtml page

Open PostEdit.xhtml from the WebContent folder and find the <rich:tabPanel switchType=”ajax”> block. This is what’s causing the problem, because it has more than one tab – one to have the user select a category from a grid on another page, and the second one for selecting a user, since these two entites have @ManyToOne relationships to the post entity, and Seam-gen can’t handle generating more than one joined object selection user interface item in this version.

I don’t want an external grid for selection of a category anyway, so we will delete the entire <rich:tabPanel> block on this page, and instead make the category selectable from a pop-up menu using a typical JSF selectOneMenu UI component.

After you delete the <rich:tabPanel> go towards the beginning of the page and locate the code block starting with <s:decorate id=”titleField” template=”layout/edit.xhtml”>.
Within that block replace <h:inputTextarea id=”title” cols=”80″ rows=”2″ required=”true” value=”#{postHome.instance.title}”/> with <h:inputText id=”title” required=”true” value=”#{postHome.instance.title}”/>

Next, add the following code block below the closing tag (</s:decorate>) for titleField:

           <s:decorate id="categoryField" template="layout/edit.xhtml">
                <ui:define name="label">Post Category</ui:define>
                <h:selectOneMenu id="category"
                           required="true"
                              value="#{postHome.instance.title}">
                     <s:selectItems value="#{categoryList.resultList}" var="cat" label="#{cat.name}" noSelectionLabel="Please select..." />
                     <s:convertEntity />
                </h:selectOneMenu>
            </s:decorate>

Continue reading

Hibernate Derived Properties – @Formula Annotation

HibernateIn Hibernate a derived property (also called a calculated property) is a read-only property whose value is calculated at fetch time using SQL expressions.

Example: For an employee entity with properties such as an id and the employee name also a monthlySalary property, you might also want to have a yearlySalary which is not necessarily stored in the database.

package net.ozar.exp.entity;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name="EMPLOYEE")
public class Employee implements java.io.Serializable {

	private static final long serialVersionUID = -7311873726885796936L;

	@Id
	@Column(name="ID")
	private Integer id;

	@Column(name="FIRST_NAME", length=31)
	private String firstName;

	@Column(name="LAST_NAME", length=31)
	private String lastName;

	@Column(name="MONTHLY_SALARY")
	private float monthlySalary;

	public Employee() {
	}

	// getters and setters
     // ...

	public float getMonthlySalary() {
		return monthlySalary;
	}

	public void setMonthlySalary(float monthlySalary) {
		this.monthlySalary = monthlySalary;
	}

     /* This artificial property - as I call it - is a kind of a calculated property, but not with Hibernate derived property support - not just yet */
	public float getYearlySalary() {
		return this.monthlySalary * 12;
	}

}

The above example gives us a simple calculation in memory for just screen output without Hibernate’s derived property or the @Formula support.  Now take a moment to reflect that we need all the employees whose yearly salary average is above $5000. Then what? In this case, you might wanna make use of Hibernate’s derived property feature.
Continue reading