How can I create Managed Beans during runtime?

[Hendrik Neumann <th...@googlemail.com>]

Hi everybody,

currently I'm developing a JSF-component which renders a set of
input-elements:

    public void encodeBegin(FacesContext myContext) throws IOException
    {
      [...]

        // create input-Elements
        HtmlInputText cssAttributeNameInput = (HtmlInputText)
myApp.createComponent(HtmlInputText.COMPONENT_TYPE);
        HtmlInputTextarea cssAttributeDescriptionInput = (HtmlInputTextarea)
myApp.createComponent(HtmlInputTextarea.COMPONENT_TYPE);

      [...]

    }

Now I need to bind these input-fields with this JavaBean:

public class BaseProperty
{
    private String name;
    private String description;

    public String getDescription()
    {
        return description;
    }
    public void setDescription(String description)
    {
        this.description = description;
    }
    public String getName()
    {
        return name;
    }
    public void setName(String name)
    {
        this.name = name;
    }
}


Normally, this would be no problem, because I would define a managed-bean in
the faces-config.xml and use the createValueBinding-Method from the
ApplicationFactory to bind my JSF-Input-components to the attribute values
of my Bean.

The problem now is: I want to create an independent  JSF-component which
should be deployed in a JAR-file and which should be usable in any
JSF-Web-Application without adding specific managed-beans to the local
faces-config.xml. Therefore I need to dynamicly create a managed bean from
my "BaseProperty"-class during runtime.

I think about something like

        createManagedBean("temporaryBean", "
de.rub.swt.csseditor.model.BaseProperty", "session");
        ValueBinding dynBinding = myApplicationFactory.createValueBinding("
temporaryBean.name");
        cssAttributeNameInput.setValue(dynBinding);

Is this possible? What must be the content of

    public void createManagedBean(String managedBeanName, String
managedBeanClass, String scope)
    {
         // ???????????
    }

Any hints or ideas?

Greetings,
Hendrik

Re: How can I create Managed Beans during runtime?

[Hendrik Neumann <th...@googlemail.com>]

Hi Matthias,

Why not adding the MB to the faces-config of your component's
> faces-config.xml file?


I already thought about such a solution as a "emergency plan", but I would
prefer the generic solution.

A managed bean is just a simple javaBean which can be looked up from
> the VariableResolver. The method resolveVariable(faces_context,
> name_of_my_bean) goes through all the scopes and looks it up & returns
> the bean than. Or create's it using the ManagedBeanBuilder, if not
> attached to any scope yet.
>
> So why not just creating a new object and storing it under the needed
> context ?
> like fc.getExternalContext().getSessionMap().put("fooBean", obj");


I think this were excactly the remarks I hoped for to solve my problem -
thanks a lot :-)

Greetings,
Hendrik

Re: How can I create Managed Beans during runtime?

[Matthias Wessendorf <ma...@apache.org>]

> Normally, this would be no problem, because I would define a managed-bean in
> the faces-config.xml and use the createValueBinding-Method from the
> ApplicationFactory to bind my JSF-Input-components to the attribute values
> of my Bean.
>
> The problem now is: I want to create an independent  JSF-component which
> should be deployed in a JAR-file and which should be usable in any
> JSF-Web-Application without adding specific managed-beans to the local
> faces-config.xml. Therefore I need to dynamicly create a managed bean from
> my "BaseProperty"-class during runtime.


Why not adding the MB to the faces-config of your component's
faces-config.xml file?


> I think about something like
>
>         createManagedBean("temporaryBean", "
> de.rub.swt.csseditor.model.BaseProperty", "session");
>         ValueBinding dynBinding =
> myApplicationFactory.createValueBinding("temporaryBean.name");
>         cssAttributeNameInput.setValue(dynBinding);
>
> Is this possible? What must be the content of
>
>     public void createManagedBean(String managedBeanName, String
> managedBeanClass, String scope)
>     {
>          // ???????????
>     }


A managed bean is just a simple javaBean which can be looked up from
the VariableResolver. The method resolveVariable(faces_context,
name_of_my_bean) goes through all the scopes and looks it up & returns
the bean than. Or create's it using the ManagedBeanBuilder, if not
attached to any scope yet.

So why not just creating a new object and storing it under the needed context ?
like fc.getExternalContext().getSessionMap().put("fooBean", obj");

-Matt

> Any hints or ideas?
>
> Greetings,
> Hendrik
>


-- 
Matthias Wessendorf

further stuff:
blog: http://jroller.com/page/mwessendorf
mail: mwessendorf-at-gmail-dot-com