Help required in writing java code in seam framework

[vasukihn]

Hi all,

I am very new to this framework. I wanted to know whether any Jboss seam developers guide book is available at store or online download?

Another question is, i am struck in writing code for adding values from the database to rich:combobox list.
Can anyone help me guiding the procedure/steps to be followed to complete the work?
As i don't have any idea of what all files to be created to add values in combobox list from the database.

Thanks
Vasuki

[amitev]

Read Seam reference manual and Seam in Action.

As for the comobox i recommend you to fetch the values using @Factory and use the factory in the child selectItems of rich:combobox

[vasukihn]

Hi Adrian,

Can you give me an example java to explain the @Factory functionality?

[sappo]

Hi Vasuki,

check out the Seam reference manual:

http://docs.jboss.org/seam/2.2.1.CR1/reference/en-US/html_single/#d0e4355

For further reading I really recommand Seam in Action.

Kind regards,
Kevin

[vasukihn]

Hi Kevin,

I have 2 entity files (Custom.java and CustomType.java). I want to have a list of CustomTypename(property of CustomType.java)as drop down in CustomEdit.xhtml file.

I have added CustomType class instance in Custom.java file and also setter and getter method for the instnace.
Later what i have to do? Just explain what functions to be written in which files?

Thanks
Vasuki

[sappo]

Hi Vasuki,

seam has build in support for converting entities. The only thing you've to do is add the s:convertEntity tag to your drop-down component.

<h:selectManyListbox value="#{yourBean.customTypeList}">
  <s:selectItems var="c" value="#{yourBean.selectedType}" label="#{c.name}"/>
  <s:convertEntity/>
</h:selectManyListbox>

//Kevin

[vasukihn]

Hi Kevin,

Please can you explain me in detail? I just have two entity files Custom.java and CustomType.java. I have added CustomType class instance in Custom.java and i have the getter and setter methods. Except this i have nothing else. What functions i have to write in each file? Once the functions are written what value should be passed to .xhtml file?

As i 'm new to this, please explain me in detail.

[sappo]

Hi Vasuki,

there is no need to change anything inside your entity classes. Just create an action class like the one below, to pass a list to your drop-down and obtain the selected value.

CustomTypeAction.java (you may want to change the scope):

@Name("customTypeAction")
@Scope(ScopeType.SESSION)
public class CustomTypeAction implements Serializable {
    @In
    EntityManager entitymanager;

    @Out
    List<CustomType> customTypeList;
    @In(required = false)
    CustomType selectedType;

    @Factory(value="customTypeList")
    public List<CustomType> initList() {
        return (ArrayList<CustomType>)
            entityManager.createQuery("select s from Schulform s").getResultList();
    }
}

*.xhtml

<h:selectManyListbox value="#{customTypeList}">
  <s:selectItems var="c" value="#{selectedType}" label="#{c.name}"/>
  <s:convertEntity/>
</h:selectManyListbox>

//Kevin

[vasukihn]

Hi Kevin,

As you said, I created CustomtypeAction.java file and wrote the code as you explained. I used my table name and fields in the query. Later added the belowcode to my CustomEdit.xhtml

<h:selectManyListbox value="#{customTypeList}">
  <s:selectItems var="c" value="#{selectedType}" label="#{c.name}"/>
  <s:convertEntity/>
</h:selectManyListbox>

When i add the above code to my CustomEdit.xhtml file i get the following error:
I didn't understand about var and label attributes of 

<s:selectItems>

tag.

java.lang.IllegalArgumentException: Expected a child component type of UISelectItem/UISelectItems for component type javax.faces.SelectMany(j_id41).  Found null.

Can you guide where i am going wrong?